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* Re: [PATCH v2 1/3] arm64: mm: Fix rodata=full block mapping support for realm guests
From: Yang Shi @ 2026-04-09 16:48 UTC (permalink / raw)
  To: Catalin Marinas, Kevin Brodsky
  Cc: Ryan Roberts, Will Deacon, David Hildenbrand (Arm), Dev Jain,
	Suzuki K Poulose, Jinjiang Tu, linux-arm-kernel, linux-kernel,
	stable
In-Reply-To: <adfDoatH8hj6zN7_@arm.com>



On 4/9/26 8:20 AM, Catalin Marinas wrote:
> On Thu, Apr 09, 2026 at 11:53:41AM +0200, Kevin Brodsky wrote:
>> On 07/04/2026 12:52, Catalin Marinas wrote:
>>>> if we have forced pte mapping then the value of
>>>> can_set_direct_map() is irrelevant - we will never need to split because we are
>>>> already pte-mapped.
>>> can_set_direct_map() is used in other places, so its value is
>>> relevant, e.g. sys_memfd_secret() is rejected if this function returns
>>> false.
>> Indeed, I have noticed this before: currently set_direct_map_*_noflush()
>> and other functions will either fail or do nothing if none of the
>> features (rodata=full, etc.) is enabled, even if we would be able to
>> split the linear map using BBML2-noabort.
> That's what I have been trying to say to Ryan ;), can_set_direct_map()
> has different meanings depending on the caller: hint that it might split
> or asking whether splitting is permitted. The latter is not captured.
> Ignoring realms, if we have BBML2_NOABORT the kernel won't force pte
> mappings under the assumption that split_kernel_leaf_mapping() is safe.
> However set_direct_map_*_noflush() won't even reach the split function
> because the "can" part says "no, you can't".
>
>> What would make more sense to me is to enable the use of BBML2-noabort
>> unconditionally if !force_pte_mapping(). We can then have
>> can_set_direct_map() return true if we have BBML2-noabort, and we no
>> longer need to check it in map_mem().
> Indeed.

I'm trying to wrap up my head for this discussion. IIUC, if none of the 
features is enabled, it means we don't need do anything because the 
direct map is not changed. For example, if vmalloc doesn't change direct 
map permission when rodata != full, there is no need to call 
set_direct_map_*_noflush(). So unconditionally checking BBML2_NOABORT 
will change the behavior unnecessarily. Did I miss something?

I think the only exception is secretmem if I don't miss something. 
Currently, secretmem is actually not supported if none of the features 
is enabled. But BBML2_NOABORT allows to lift the restriction.

Thanks,
Yang


>
>> This is a functional change that doesn't have anything to do with realms
>> so it should probably be a separate series - happy to take care of it
>> once the dust settles on the realm handling.
> I think it can be done in parallel, it shouldn't interfere with realms.
> The realm part should just affect force_pte_mapping() and
> can_set_direct_map() should return just what's possible, not what may
> need to set the direct map.
>



^ permalink raw reply

* Re: [PATCH v2 2/4] perf: Fix uninitialized bitfields in perf_clear_branch_entry_bitfields()
From: Leo Yan @ 2026-04-09 16:28 UTC (permalink / raw)
  To: Puranjay Mohan
  Cc: bpf, Puranjay Mohan, Alexei Starovoitov, Andrii Nakryiko,
	Daniel Borkmann, Martin KaFai Lau, Eduard Zingerman,
	Kumar Kartikeya Dwivedi, Will Deacon, Mark Rutland,
	Catalin Marinas, Rob Herring, Breno Leitao, linux-arm-kernel,
	linux-perf-users, kernel-team
In-Reply-To: <20260318171706.2840512-3-puranjay@kernel.org>

On Wed, Mar 18, 2026 at 10:16:56AM -0700, Puranjay Mohan wrote:

[...]

> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index 48d851fbd8ea..d7f39b7e9cda 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h

BTW, I found you didn't include correct maintainers for perf core
changes.  You might need to loop them in the new version.


^ permalink raw reply

* Re: [PATCH] arm64: mte: Skip TFSR_EL1 checks and barriers in synchronous tag check mode
From: Catalin Marinas @ 2026-04-09 16:27 UTC (permalink / raw)
  To: David Hildenbrand (Arm)
  Cc: Muhammad Usama Anjum, Will Deacon, Matthew Wilcox (Oracle),
	Thomas Huth, Andrew Morton, Lance Yang, Yeoreum Yun,
	linux-arm-kernel, linux-kernel
In-Reply-To: <c347fdc9-90b4-43ac-8c2e-559248777ba8@kernel.org>

On Wed, Mar 25, 2026 at 12:46:40PM +0100, David Hildenbrand wrote:
> On 3/11/26 18:50, Muhammad Usama Anjum wrote:
> > In MTE synchronous mode, tag check faults are reported as immediate
> > Data Abort exceptions. The TFSR_EL1.TF1 bit is never set, since faults
> > never go through the asynchronous path. Therefore, reading TFSR_EL1
> > and executing data and instruction barriers on kernel entry, exit,
> > context switch, and suspend is unnecessary overhead in sync mode.
> > 
> > The exit path (mte_check_tfsr_exit) and the assembly paths
> > (check_mte_async_tcf / clear_mte_async_tcf in entry.S) already had this
> > check.
> 
> Right, that's for user space (TFSR_EL1.TF0 IIUC). What you are adding is
> for KASAN. Maybe make that clearer.

Yeah, I'll tweak the commit message a bit. Even
system_uses_mte_async_or_asymm_mode() should be renamed to something
resembling kasan but I'll leave the function name as is for now.

-- 
Catalin


^ permalink raw reply

* [PATCH] arm64: Kconfig: fix duplicate word in CMDLINE help text
From: Michael Ugrin @ 2026-04-09 16:24 UTC (permalink / raw)
  To: Catalin Marinas, Will Deacon
  Cc: linux-arm-kernel, linux-kernel, Michael Ugrin

Remove duplicate 'the' in the CMDLINE config help text.

Signed-off-by: Michael Ugrin <mugrinphoto@gmail.com>
---
 arch/arm64/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 9ea19b74b..85d952740 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -2373,7 +2373,7 @@ config CMDLINE
 	default ""
 	help
 	  Provide a set of default command-line options at build time by
-	  entering them here. As a minimum, you should specify the the
+	  entering them here. As a minimum, you should specify the
 	  root device (e.g. root=/dev/nfs).
 
 choice
-- 
2.51.2.windows.1



^ permalink raw reply related

* Re: BUG: net-next (7.0-rc6 based and later) fails to boot on Jetson Xavier NX
From: Russell King (Oracle) @ 2026-04-09 16:16 UTC (permalink / raw)
  To: Linus Torvalds
  Cc: Will Deacon, Robin Murphy, netdev, linux-arm-kernel, linux-kernel,
	iommu, linux-ext4, dmaengine, Marek Szyprowski, Theodore Ts'o,
	Andreas Dilger, Vinod Koul, Frank Li
In-Reply-To: <CAHk-=whO3F1u+nme4cnYMy5baYmb7CH=wE63dcNaPLWD0vKaew@mail.gmail.com>

On Thu, Apr 09, 2026 at 08:37:53AM -0700, Linus Torvalds wrote:
> On Thu, 9 Apr 2026 at 05:24, Will Deacon <will@kernel.org> wrote:
> >
> > On Wed, Apr 08, 2026 at 08:52:32PM +0100, Russell King (Oracle) wrote:
> > > What's the status on the iommu fix? Is it merged into mainline yet?
> > > If it isn't already, that means net-next remains unbootable going
> > > into the merge window without manually carrying the fix locally.
> >
> > I'll pick it up for 7.0 in the iommu tree.
> 
> ... and now it's in my tree.

Thanks, I see you merged it prior to the net tree, which should mean
the fix finds its way into net-next! Yay! Double thanks for that!

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!


^ permalink raw reply

* Re: [PATCH] arm64: syscall: use cntvct_el0 for kstack offset randomization
From: Kees Cook @ 2026-04-09 16:17 UTC (permalink / raw)
  To: Xu Laiguang, Ryan Roberts
  Cc: catalin.marinas, will, gustavoars, linux-arm-kernel,
	linux-hardening
In-Reply-To: <20260409095322.1774250-1-xulaiguang@lixiang.com>

On Thu, Apr 09, 2026 at 09:53:22AM +0000, Xu Laiguang wrote:
> On PREEMPT_RT kernels, get_random_u16() can suffer significant lock
> contention in the syscall hot path.  The batched entropy layer uses
> local_lock, which on RT maps to a real spinlock.  When a batch refill
> is in progress, other tasks on the same CPU block on the lock.  Under
> heavy syscall load on a 24-core RT system, worst-case latencies of
> 16.65ms have been observed.
> 
>  contended   total wait     max wait     caller
>        307     86.18 ms     16.65 ms     get_random_u16+0x64
> 
> The kstack offset randomization only needs 6 bits of entropy (the
> value is masked by KSTACK_OFFSET_MAX to bits [9:4] on 64-bit).  This
> does not require cryptographic-strength randomness -- the goal is to
> make the kernel stack offset unpredictable enough to frustrate stack
> layout attacks.
> 
> Other architectures already use lightweight hardware counters for this
> purpose:
>   - x86:       rdtsc()              (arch/x86/include/asm/entry-common.h)
>   - powerpc:   mftb()               (arch/powerpc/kernel/syscall.c)
>   - loongarch: drdtime()            (arch/loongarch/kernel/syscall.c)
>   - s390:      get_tod_clock_fast()  (arch/s390/include/asm/entry-common.h)
> 
> Replace get_random_u16() with a bare read of cntvct_el0 (the ARM
> generic timer virtual count register).  The read is performed without
> ISB or arch_counter_enforce_ordering because kstack randomization does
> not require timing accuracy -- only unpredictability.
> 
> Signed-off-by: Xu Laiguang <xulaiguang@lixiang.com>

Everything here has been replaced recently. Can you check again with the
-next tree?

https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/log/?h=for-next/hardening

See commits:
	randomize_kstack: Maintain kstack_offset per task
	randomize_kstack: Unify random source across arches

-Kees

> ---
>  arch/arm64/kernel/syscall.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
> index c062badd1a56..c0ee9fa529ca 100644
> --- a/arch/arm64/kernel/syscall.c
> +++ b/arch/arm64/kernel/syscall.c
> @@ -35,6 +35,21 @@ static long __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn)
>  	return syscall_fn(regs);
>  }
>  
> +/*
> + * Read the virtual counter without ISB or other ordering barriers.
> + * This is intentional: kstack randomization only needs unpredictability,
> + * not timing accuracy.  Speculative execution of the read, if it occurs,
> + * actually helps by making the precise value less predictable to an
> + * attacker.
> + */
> +static inline u64 kstack_entropy_cntvct(void)
> +{
> +	u64 cnt;
> +
> +	asm volatile("mrs %0, cntvct_el0" : "=r"(cnt));
> +	return cnt;
> +}
> +
>  static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
>  			   unsigned int sc_nr,
>  			   const syscall_fn_t syscall_table[])
> @@ -62,7 +77,7 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
>  	 *
>  	 * The resulting 6 bits of entropy is seen in SP[9:4].
>  	 */
> -	choose_random_kstack_offset(get_random_u16());
> +	choose_random_kstack_offset(kstack_entropy_cntvct());
>  }
>  
>  static inline bool has_syscall_work(unsigned long flags)
> -- 
> 2.43.0
> 
> 声明:这封邮件只允许文件接收者阅读,有很高的机密性要求。禁止其他人使用、打开、复制或转发里面的任何内容。如果本邮件错误地发给了你,请联系邮件发出者并删除这个文件。机密及法律的特权并不因为误发邮件而放弃或丧失。任何提出的观点或意见只属于作者的个人见解,并不一定代表本公司。
> Disclaimer: This email is intended to be read only by the designated recipient of the document and has high confidentiality requirements. Anyone else is prohibited from using, opening, copying or forwarding any of the contents inside. If this email was sent to you by mistake, please contact the sender of the email and delete this file immediately. Confidentiality and legal privileges are not waived or lost by misdirected emails. Any views or opinions expressed in the email are those of the author and do not necessarily represent those of the Company.
> 

-- 
Kees Cook


^ permalink raw reply

* Re: [PATCH v14 00/10] arm64: entry: Convert to Generic Entry
From: Kees Cook @ 2026-04-09 16:14 UTC (permalink / raw)
  To: Jinjie Ruan
  Cc: mark.rutland, peterz, catalin.marinas, ldv, edumazet, will, mingo,
	thuth, ryan.roberts, arnd, anshuman.khandual, kevin.brodsky,
	pengcan, broonie, mathieu.desnoyers, luto, linux-arm-kernel, wad,
	song, linusw, oleg, linux-kernel, tglx, liqiang01, yeoreum.yun
In-Reply-To: <174e6d08-4922-f42f-2899-4c5b0df13469@huawei.com>

On Thu, Apr 09, 2026 at 02:29:04PM +0800, Jinjie Ruan wrote:
> On 2026/3/20 18:26, Jinjie Ruan wrote:
> > Currently, x86, Riscv, Loongarch use the Generic Entry which makes
> > maintainers' work easier and codes more elegant. arm64 has already
> > successfully switched to the Generic IRQ Entry in commit
> > b3cf07851b6c ("arm64: entry: Switch to generic IRQ entry"), it is
> > time to completely convert arm64 to Generic Entry.
> > 
> > The goal is to bring arm64 in line with other architectures that already
> > use the generic entry infrastructure, reducing duplicated code and
> > making it easier to share future changes in entry/exit paths, such as
> > "Syscall User Dispatch" and RSEQ optimizations.
> 
> Just a quick ping to see if this series is good to go. Do I need to
> provide a new version rebased on the latest arm64 for-next/generic-entry
> branches, or is the current version acceptable?

One thing I see is Sashiko's comments on seccomp:
https://sashiko.dev/#/patchset/20260320102620.1336796-1-ruanjinjie%40huawei.com
where "ret", when not 0 or -1, will override the syscall number. While
that's not currently possible, it'd be better to catch that, or rather,
avoid the "ret ? : syscall" logic which isn't useful here. "ret" should
probably be local to the "if (flags & _TIF_SECCOMP)" scope.

-- 
Kees Cook


^ permalink raw reply

* Re: [PATCH 2/3] pwm: rp1: Add RP1 PWM controller driver
From: Andrea della Porta @ 2026-04-09 16:16 UTC (permalink / raw)
  To: Uwe Kleine-König
  Cc: Andrea della Porta, linux-pwm, Rob Herring, Krzysztof Kozlowski,
	Conor Dooley, Florian Fainelli,
	Broadcom internal kernel review list, devicetree,
	linux-rpi-kernel, linux-arm-kernel, linux-kernel, Naushir Patuck,
	Stanimir Varbanov
In-Reply-To: <adLTwOTbkJ0VQXy6@monoceros>

Hi Uwe,

On 23:45 Sun 05 Apr     , Uwe Kleine-König wrote:
> Hello Andrea,
> 
> On Fri, Apr 03, 2026 at 04:31:55PM +0200, Andrea della Porta wrote:
> > From: Naushir Patuck <naush@raspberrypi.com>
> > 
> > The Raspberry Pi RP1 southbridge features an embedded PWM
> > controller with 4 output channels, alongside an RPM interface
> > to read the fan speed on the Raspberry Pi 5.
> > 
> > Add the supporting driver.
> > 
> > Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
> > Co-developed-by: Stanimir Varbanov <svarbanov@suse.de>
> > Signed-off-by: Stanimir Varbanov <svarbanov@suse.de>
> > Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
> > ---
> >  drivers/pwm/Kconfig   |  10 ++
> >  drivers/pwm/Makefile  |   1 +
> >  drivers/pwm/pwm-rp1.c | 244 ++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 255 insertions(+)
> >  create mode 100644 drivers/pwm/pwm-rp1.c
> > 
> > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > index 6f3147518376a..22e4fc6385da2 100644
> > --- a/drivers/pwm/Kconfig
> > +++ b/drivers/pwm/Kconfig
> > @@ -625,6 +625,16 @@ config PWM_ROCKCHIP
> >  	  Generic PWM framework driver for the PWM controller found on
> >  	  Rockchip SoCs.
> >  
> > +config PWM_RP1
> 
> I prefer PWM_RASPBERRYPI1, or PWM_RASPBERRYPI_RP1 here.

Ack.

> 
> > +	tristate "RP1 PWM support"
> > +	depends on MISC_RP1 || COMPILE_TEST
> > +	depends on HWMON
> > +	help
> > +	  PWM framework driver for Raspberry Pi RP1 controller
> > +
> > +	  To compile this driver as a module, choose M here: the module
> > +	  will be called pwm-rp1.
> > +
> >  config PWM_SAMSUNG
> >  	tristate "Samsung PWM support"
> >  	depends on PLAT_SAMSUNG || ARCH_S5PV210 || ARCH_EXYNOS || COMPILE_TEST
> > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> > index 0dc0d2b69025d..895a7c42fe9c0 100644
> > --- a/drivers/pwm/Makefile
> > +++ b/drivers/pwm/Makefile
> > @@ -56,6 +56,7 @@ obj-$(CONFIG_PWM_RENESAS_RZG2L_GPT)	+= pwm-rzg2l-gpt.o
> >  obj-$(CONFIG_PWM_RENESAS_RZ_MTU3)	+= pwm-rz-mtu3.o
> >  obj-$(CONFIG_PWM_RENESAS_TPU)	+= pwm-renesas-tpu.o
> >  obj-$(CONFIG_PWM_ROCKCHIP)	+= pwm-rockchip.o
> > +obj-$(CONFIG_PWM_RP1)		+= pwm-rp1.o
> >  obj-$(CONFIG_PWM_SAMSUNG)	+= pwm-samsung.o
> >  obj-$(CONFIG_PWM_SIFIVE)	+= pwm-sifive.o
> >  obj-$(CONFIG_PWM_SL28CPLD)	+= pwm-sl28cpld.o
> > diff --git a/drivers/pwm/pwm-rp1.c b/drivers/pwm/pwm-rp1.c
> > new file mode 100644
> > index 0000000000000..0a1c1c1dd27e9
> > --- /dev/null
> > +++ b/drivers/pwm/pwm-rp1.c
> > @@ -0,0 +1,244 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * pwm-rp1.c
> > + *
> > + * Raspberry Pi RP1 PWM.
> > + *
> > + * Copyright © 2026 Raspberry Pi Ltd.
> > + *
> > + * Author: Naushir Patuck (naush@raspberrypi.com)
> > + *
> > + * Based on the pwm-bcm2835 driver by:
> > + * Bart Tanghe <bart.tanghe@thomasmore.be>
> > + */
> 
> Please add a paragraph here named "Limitations" in the same format as
> several other drivers describing how the driver behaves on disable and
> configuration changes (can glitches occur? Is the currently running
> period completed or aborted?)

Ack.

> 
> > +#include <linux/bitops.h>
> > +#include <linux/clk.h>
> > +#include <linux/err.h>
> > +#include <linux/hwmon.h>
> > +#include <linux/io.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pwm.h>
> > +
> > +#define PWM_GLOBAL_CTRL		0x000
> > +#define PWM_CHANNEL_CTRL(x)	(0x014 + ((x) * 0x10))
> > +#define PWM_RANGE(x)		(0x018 + ((x) * 0x10))
> > +#define PWM_PHASE(x)		(0x01C + ((x) * 0x10))
> > +#define PWM_DUTY(x)		(0x020 + ((x) * 0x10))
> > +
> > +/* 8:FIFO_POP_MASK + 0:Trailing edge M/S modulation */
> > +#define PWM_CHANNEL_DEFAULT	(BIT(8) + BIT(0))
> > +#define PWM_CHANNEL_ENABLE(x)	BIT(x)
> > +#define PWM_POLARITY		BIT(3)
> > +#define SET_UPDATE		BIT(31)
> > +#define PWM_MODE_MASK		GENMASK(1, 0)
> > +
> > +#define NUM_PWMS		4
> 
> Please prefix all #defines by something driver specific (e.g. RP1_PWM_).

Ack.

> 
> > +
> > +struct rp1_pwm {
> > +	void __iomem	*base;
> > +	struct clk	*clk;
> > +};
> > +
> > +static const struct hwmon_channel_info * const rp1_fan_hwmon_info[] = {
> > +	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
> > +	NULL
> > +};
> > +
> > +static umode_t rp1_fan_hwmon_is_visible(const void *data, enum hwmon_sensor_types type,
> > +					u32 attr, int channel)
> > +{
> > +	umode_t mode = 0;
> > +
> > +	if (type == hwmon_fan && attr == hwmon_fan_input)
> > +		mode = 0444;
> > +
> > +	return mode;
> > +}
> > +
> > +static int rp1_fan_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> > +			      u32 attr, int channel, long *val)
> > +{
> > +	struct rp1_pwm *rp1 = dev_get_drvdata(dev);
> > +
> > +	if (type != hwmon_fan || attr != hwmon_fan_input)
> > +		return -EOPNOTSUPP;
> > +
> > +	*val = readl(rp1->base + PWM_PHASE(2));
> > +
> > +	return 0;
> > +}
> 
> I don't like having hwmon bits in pwm drivers. Is the PWM only usable
> for a fan? I guess the hwmon parts should be dropped and a pwm-fan
> defined in dt.

The pwm-fan generic driver expects an interrupt to count the RPM, while
on RP1 this data is passed via a register filled by the RP1 fw running
on the internal core. Instead of changing the generic pwm-fan driver,
I'll add a syscon to export this register which will be read by a new
device/driver registering an hwmon device.

> 
> > +static const struct hwmon_ops rp1_fan_hwmon_ops = {
> > +	.is_visible = rp1_fan_hwmon_is_visible,
> > +	.read = rp1_fan_hwmon_read,
> > +};
> > +
> > +static const struct hwmon_chip_info rp1_fan_hwmon_chip_info = {
> > +	.ops = &rp1_fan_hwmon_ops,
> > +	.info = rp1_fan_hwmon_info,
> > +};
> > +
> > +static void rp1_pwm_apply_config(struct pwm_chip *chip, struct pwm_device *pwm)
> > +{
> > +	struct rp1_pwm *rp1 = pwmchip_get_drvdata(chip);
> > +	u32 value;
> > +
> > +	value = readl(rp1->base + PWM_GLOBAL_CTRL);
> > +	value |= SET_UPDATE;
> > +	writel(value, rp1->base + PWM_GLOBAL_CTRL);
> > +}
> > +
> > +static int rp1_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> > +{
> > +	struct rp1_pwm *rp1 = pwmchip_get_drvdata(chip);
> > +
> > +	writel(PWM_CHANNEL_DEFAULT, rp1->base + PWM_CHANNEL_CTRL(pwm->hwpwm));
> 
> Please add a comment about what this does.

Ack.

> 
> > +	return 0;
> > +}
> > +
> > +static void rp1_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> > +{
> > +	struct rp1_pwm *rp1 = pwmchip_get_drvdata(chip);
> > +	u32 value;
> > +
> > +	value = readl(rp1->base + PWM_CHANNEL_CTRL(pwm->hwpwm));
> > +	value &= ~PWM_MODE_MASK;
> > +	writel(value, rp1->base + PWM_CHANNEL_CTRL(pwm->hwpwm));
> > +
> > +	rp1_pwm_apply_config(chip, pwm);
> 
> What is the purpose of this call?

To update the configuration on the next PWM strobe in order to avoid
glitches. I'll add a short comment in the code.

> 
> > +}
> > +
> > +static int rp1_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> > +			 const struct pwm_state *state)
> > +{
> > +	struct rp1_pwm *rp1 = pwmchip_get_drvdata(chip);
> > +	unsigned long clk_rate = clk_get_rate(rp1->clk);
> > +	unsigned long clk_period;
> > +	u32 value;
> > +
> > +	if (!clk_rate) {
> > +		dev_err(&chip->dev, "failed to get clock rate\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	/* set period and duty cycle */
> > +	clk_period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, clk_rate);
> 
> DIV_ROUND_CLOSEST is wrong here. (I don't go into details as .apply()
> should be dropped.)

Ack.

> 
> > +	writel(DIV_ROUND_CLOSEST(state->duty_cycle, clk_period),
> 
> Dividing by the result of a division loses precision.
> 
> > +	       rp1->base + PWM_DUTY(pwm->hwpwm));
> > +
> > +	writel(DIV_ROUND_CLOSEST(state->period, clk_period),
> > +	       rp1->base + PWM_RANGE(pwm->hwpwm));
> > +
> > +	/* set polarity */
> > +	value = readl(rp1->base + PWM_CHANNEL_CTRL(pwm->hwpwm));
> > +	if (state->polarity == PWM_POLARITY_NORMAL)
> > +		value &= ~PWM_POLARITY;
> > +	else
> > +		value |= PWM_POLARITY;
> > +	writel(value, rp1->base + PWM_CHANNEL_CTRL(pwm->hwpwm));
> > +
> > +	/* enable/disable */
> > +	value = readl(rp1->base + PWM_GLOBAL_CTRL);
> > +	if (state->enabled)
> > +		value |= PWM_CHANNEL_ENABLE(pwm->hwpwm);
> > +	else
> > +		value &= ~PWM_CHANNEL_ENABLE(pwm->hwpwm);
> > +	writel(value, rp1->base + PWM_GLOBAL_CTRL);
> > +
> > +	rp1_pwm_apply_config(chip, pwm);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct pwm_ops rp1_pwm_ops = {
> > +	.request = rp1_pwm_request,
> > +	.free = rp1_pwm_free,
> > +	.apply = rp1_pwm_apply,
> 
> Please implement the waveform callbacks instead of .apply().

Ack.

> 
> > +};
> > +
> > +static int rp1_pwm_probe(struct platform_device *pdev)
> > +{
> > +	struct device *dev = &pdev->dev;
> > +	struct device *hwmon_dev;
> > +	struct pwm_chip *chip;
> > +	struct rp1_pwm *rp1;
> > +	int ret;
> > +
> > +	chip = devm_pwmchip_alloc(dev, NUM_PWMS, sizeof(*rp1));
> > +	if (IS_ERR(chip))
> > +		return PTR_ERR(chip);
> > +
> > +	rp1 = pwmchip_get_drvdata(chip);
> > +
> > +	rp1->base = devm_platform_ioremap_resource(pdev, 0);
> > +	if (IS_ERR(rp1->base))
> > +		return PTR_ERR(rp1->base);
> > +
> > +	rp1->clk = devm_clk_get_enabled(dev, NULL);
> > +	if (IS_ERR(rp1->clk))
> > +		return dev_err_probe(dev, PTR_ERR(rp1->clk), "clock not found\n");
> 
> Please start error messages with a capital letter.

Ack.

> 
> > +
> > +	ret = devm_clk_rate_exclusive_get(dev, rp1->clk);
> 
> After this call you can determine the rate just once and fail if it's ==
> 0.

Ack.

> 
> > +	if (ret)
> > +		return dev_err_probe(dev, ret, "fail to get exclusive rate\n");
> > +
> > +	chip->ops = &rp1_pwm_ops;
> > +
> > +	platform_set_drvdata(pdev, chip);
> > +
> > +	ret = devm_pwmchip_add(dev, chip);
> > +	if (ret)
> > +		return dev_err_probe(dev, ret, "failed to register PWM chip\n");
> > +
> > +	hwmon_dev = devm_hwmon_device_register_with_info(dev, "rp1_fan_tach", rp1,
> > +							 &rp1_fan_hwmon_chip_info,
> > +							 NULL);
> > +
> > +	if (IS_ERR(hwmon_dev))
> > +		return dev_err_probe(dev, PTR_ERR(hwmon_dev),
> > +				     "failed to register hwmon fan device\n");
> > +
> > +	return 0;
> > +}
> > +
> > +static int rp1_pwm_suspend(struct device *dev)
> > +{
> > +	struct rp1_pwm *rp1 = dev_get_drvdata(dev);
> > +
> > +	clk_disable_unprepare(rp1->clk);
> > +
> > +	return 0;
> > +}
> > +
> > +static int rp1_pwm_resume(struct device *dev)
> > +{
> > +	struct rp1_pwm *rp1 = dev_get_drvdata(dev);
> > +
> > +	return clk_prepare_enable(rp1->clk);
> 
> Hmm, if this fails and then the driver is unbound, the clk operations
> are not balanced.

I'll add some flags to check if the clock is really enabled or not.

Regards,
Andrea

> 
> > +}
> > +
> > +static DEFINE_SIMPLE_DEV_PM_OPS(rp1_pwm_pm_ops, rp1_pwm_suspend, rp1_pwm_resume);
> > +
> > +static const struct of_device_id rp1_pwm_of_match[] = {
> > +	{ .compatible = "raspberrypi,rp1-pwm" },
> > +	{ /* sentinel */ }
> > +};
> > +MODULE_DEVICE_TABLE(of, rp1_pwm_of_match);
> > +
> > +static struct platform_driver rp1_pwm_driver = {
> > +	.probe = rp1_pwm_probe,
> > +	.driver = {
> > +		.name = "rp1-pwm",
> > +		.of_match_table = rp1_pwm_of_match,
> > +		.pm = pm_ptr(&rp1_pwm_pm_ops),
> > +	},
> > +};
> > +module_platform_driver(rp1_pwm_driver);
> > +
> > +MODULE_DESCRIPTION("RP1 PWM driver");
> > +MODULE_AUTHOR("Naushir Patuck <naush@raspberrypi.com>");
> > +MODULE_LICENSE("GPL");
> > -- 
> > 2.35.3
> > 
> 
> Best regards
> Uwe




^ permalink raw reply

* Re: [PATCH v7 7/7] KVM: arm64: Normalize cache configuration
From: David Woodhouse @ 2026-04-09 16:10 UTC (permalink / raw)
  To: Marc Zyngier
  Cc: Gutierrez Cantu, Bernardo, alexandru.elisei, alyssa, asahi,
	broonie, catalin.marinas, james.morse, kvmarm, linux-arm-kernel,
	linux-kernel, marcan, mathieu.poirier, oliver.upton,
	suzuki.poulose, sven, will
In-Reply-To: <86tstk2l4w.wl-maz@kernel.org>

[-- Attachment #1: Type: text/plain, Size: 2531 bytes --]

On Thu, 2026-04-09 at 16:45 +0100, Marc Zyngier wrote:
> On Thu, 09 Apr 2026 15:51:59 +0100, David Woodhouse <dwmw2@infradead.org> wrote:
> > On Thu, 2026-04-09 at 14:36 +0100, Marc Zyngier wrote:
> 
> > > We have never guaranteed host downgrade. It almost never works.
> >
> > Huh? Host downgrade absolutely *does* work; KVM on Arm isn't a toy.
> > We'd never be able to ship a new kernel if we didn't know we could roll
> > it *back* if we needed to.
> 
> You have clearly been lucky so far, because I'd never such claim.

It's not luck. We do a *lot* of testing, both within the guest checking
that what it sees is identical between old and new environments, and
repeated live upgrade/downgrade cycles between versions as well as
migration back and forth, and hibernate/resume from one to the other.

> > 
> > I *know* that you know perfectly well that we actively test host
> > downgrades prior to every rollout of a new kernel. So I'm a little
> > confused about what you're trying to say here, Marc.
> 
> I said exactly this: we make no effort to ensure that a guest started
> on a version of the kernel can be migrated to an older version -- the
> state space might be different.

You said "it almost never works". If that were the case, then I would
suggest that KVM on arm64 would be entirely unsuitable as a production
platform for virtual hosting. But thankfully it isn't my experience at
all.

Sure, we've occasionally found breakage, such as this commit and the
vGIC 'IMP_REV_1' thing being discussed in a separate thread, but those
are the exceptions rather than the norm.

(And yes, we need to do better than just reverting the offending
commits when we find them, and fix the issues properly upstream. Which
is what I'm doing now, belatedly).

> > 
> > Now that the values are writable, but userspace can't easily see *what*
> > they would have been in the previous kernel. So having the capability
> > to ask KVM to set them to those values seems like it might be useful.
> 
> Well, it's only a patch away.

Indeed so. When I asked what I was missing, I was *kind* of hoping
someone would tell me I'm wrong and that I can get the original values
from userspace either through sysfs or some other means, but in the
absence of that:
https://lore.kernel.org/lkml/7fb7b823c68e04321eb532a5b8ae21a818d4926d.camel@infradead.org/

(Lore is being insanely slow today but it *will* be there, and the
marc.info first alternative it offers does already have the message).

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^ permalink raw reply

* Re: [PATCH] mm/arm: pgtable: remove young bit check for pte_valid_user
From: Russell King (Oracle) @ 2026-04-09 16:00 UTC (permalink / raw)
  To: Brian Ruley; +Cc: Will Deacon, Steve Capper, linux-arm-kernel, linux-kernel
In-Reply-To: <adfDEMK8EbIjPu3J@zoo11.fihel.lab.ge-healthcare.net>

On Thu, Apr 09, 2026 at 06:17:36PM +0300, Brian Ruley wrote:
> However, in the case I describe, if VA_B is mapped immediately to pfn_q
> after it been has unmapped and freed for VA_A, then it's quite possible
> that the page is still indexed in the cache.

True.

> The hypothesis is that if
> VA_A and VA_B land in the same I-cache set and VA_A old cache entry
> still exists (tagged with pfn_q), then the CPU can fetch stale
> instructions because the tag will match. That's one reason why we need
> to invalidate the cache, but that will be skipped in the path:
> 
>     migrate_pages
>      migrate_pages_batch
>       migrate_folio_move
>        remove_migration_ptes
>         remove_migration_pte
>          set_pte_at
>           set_ptes
>            __sync_icache_dcache  (skipped if !young)
>             set_pte_ext

In this case, if the old PTE was marked !young, then the new PTE will
have:
	pte = pte_mkold(pte);

on it, which marks it !young. As you say, __sync_icache_dcache() will
be skipped. While a PTE entry will be set for the kernel, the code in
set_pte_ext() will *not* establish a hardware PTE entry. For the
2-level pte code:

        tst     r1, #L_PTE_YOUNG	@ <- results in Z being set
        tstne   r1, #L_PTE_VALID	@ <- not executed
        eorne   r1, r1, #L_PTE_NONE	@ <- not executed
        tstne   r1, #L_PTE_NONE		@ <- not executed
        moveq   r3, #0			@ <- hardware PTE value
 ARM(   str     r3, [r0, #2048]! )	@ <- writes hardware PTE

So, for a !young PTE, the hardware PTE entry is written as zero,
which means accesses should fault, which will then cause the PTE to
be marked young.

For the 3-level case, the L_PTE_YOUNG bit corresponds with the AF bit
in the PTE, and there aren't split Linux / hardware PTE entries. AF
being clear should result in a page fault being generated for the
kernel to handle making the PTE young.

In both of these cases, set_ptes() will need to be called with the
updated PTE which will now be marked young, and that will result in
the I-cache being flushed.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!


^ permalink raw reply

* Re: [PATCH v10 17/20] coresight: trbe: Save and restore state across CPU low power state
From: Leo Yan @ 2026-04-09 15:54 UTC (permalink / raw)
  To: James Clark
  Cc: coresight, linux-arm-kernel, Suzuki K Poulose, Mike Leach,
	Yeoreum Yun, Mark Rutland, Will Deacon, Yabin Cui, Keita Morisaki,
	Yuanfang Zhang, Greg Kroah-Hartman, Alexander Shishkin,
	Tamas Petz, Thomas Gleixner, Peter Zijlstra
In-Reply-To: <e2241b98-92a6-45e0-a9d3-061f1ed69ae1@linaro.org>

On Thu, Apr 09, 2026 at 11:52:06AM +0100, James Clark wrote:
> On 05/04/2026 4:02 pm, Leo Yan wrote:
> > From: Yabin Cui <yabinc@google.com>
> > 
> > TRBE context can be lost when a CPU enters low power states.  If a trace
> > source is restored while TRBE is not, tracing may run without an active
> > sink, which can lead to hangs on some devices (e.g., Pixel 9).
> 
> Can't this still happen if saving the source times out on "wait for
> TRCSTATR.IDLE to go up"?
> 
> That would make coresight_pm_save() exit early, not saving the active TRBE
> state. Then when coresight_pm_restore() is called it restores a stale
> inactive sink, then enables the source again which is the state that can
> hang.

Hmm... I don't expect this to happen anyway.

If CPU PM enter fails and returns an error, it will bail out early of
the idle flow and the CPU will not proceed entering low power states;
therefore, the restore flow does not exist.

Thanks,
Leo


^ permalink raw reply

* [PATCH v12 23/25] drm/tests: bridge: Add test for HDMI output bus formats helper
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

The common atomic_get_output_bus_fmts helper for HDMI bridge connectors,
called drm_atomic_helper_bridge_get_hdmi_output_bus_fmts, should return
an array of output bus formats depending on the supported formats of the
connector, and the current output BPC.

Add a test to exercise some of this helper.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/tests/drm_bridge_test.c | 184 ++++++++++++++++++++++++++++++++
 1 file changed, 184 insertions(+)

diff --git a/drivers/gpu/drm/tests/drm_bridge_test.c b/drivers/gpu/drm/tests/drm_bridge_test.c
index cb821c606070..d9bd930b1197 100644
--- a/drivers/gpu/drm/tests/drm_bridge_test.c
+++ b/drivers/gpu/drm/tests/drm_bridge_test.c
@@ -5,6 +5,7 @@
 #include <linux/cleanup.h>
 #include <linux/media-bus-format.h>
 
+#include <drm/drm_atomic_helper.h>
 #include <drm/drm_atomic_state_helper.h>
 #include <drm/drm_atomic_uapi.h>
 #include <drm/drm_bridge.h>
@@ -118,6 +119,28 @@ static const struct drm_bridge_funcs drm_test_bridge_atomic_funcs = {
 	.atomic_reset		= drm_atomic_helper_bridge_reset,
 };
 
+static int dummy_clear_infoframe(struct drm_bridge *bridge)
+{
+	return 0;
+}
+
+static int dummy_write_infoframe(struct drm_bridge *bridge, const u8 *buffer,
+				 size_t len)
+{
+	return 0;
+}
+
+static const struct drm_bridge_funcs drm_test_bridge_bus_fmts_funcs = {
+	.atomic_get_output_bus_fmts	= drm_atomic_helper_bridge_get_hdmi_output_bus_fmts,
+	.atomic_destroy_state		= drm_atomic_helper_bridge_destroy_state,
+	.atomic_duplicate_state		= drm_atomic_helper_bridge_duplicate_state,
+	.atomic_reset			= drm_atomic_helper_bridge_reset,
+	.hdmi_write_avi_infoframe	= dummy_write_infoframe,
+	.hdmi_write_hdmi_infoframe	= dummy_write_infoframe,
+	.hdmi_clear_avi_infoframe	= dummy_clear_infoframe,
+	.hdmi_clear_hdmi_infoframe	= dummy_clear_infoframe,
+};
+
 /**
  * struct fmt_tuple - a tuple of input/output MEDIA_BUS_FMT_*
  */
@@ -539,6 +562,83 @@ drm_test_bridge_chain_init(struct kunit *test, unsigned int num_bridges,
 	return priv;
 }
 
+static struct drm_bridge_init_priv *
+drm_test_bridge_hdmi_init(struct kunit *test, const struct drm_bridge_funcs *funcs,
+			  unsigned int supported_formats, int max_bpc)
+{
+	struct drm_bridge_init_priv *priv;
+	struct drm_encoder *enc;
+	struct drm_bridge *bridge;
+	struct drm_device *drm;
+	struct device *dev;
+	int ret;
+
+	dev = drm_kunit_helper_alloc_device(test);
+	if (IS_ERR(dev))
+		return ERR_CAST(dev);
+
+	priv = drm_kunit_helper_alloc_drm_device(test, dev,
+						 struct drm_bridge_init_priv, drm,
+						 DRIVER_MODESET | DRIVER_ATOMIC);
+	if (IS_ERR(priv))
+		return ERR_CAST(priv);
+
+	priv->test_bridge = devm_drm_bridge_alloc(dev, struct drm_bridge_priv, bridge, funcs);
+	if (IS_ERR(priv->test_bridge))
+		return ERR_CAST(priv->test_bridge);
+
+	priv->test_bridge->data = priv;
+
+	drm = &priv->drm;
+	priv->plane = drm_kunit_helper_create_primary_plane(test, drm,
+							    NULL,
+							    NULL,
+							    NULL, 0,
+							    NULL);
+	if (IS_ERR(priv->plane))
+		return ERR_CAST(priv->plane);
+
+	priv->crtc = drm_kunit_helper_create_crtc(test, drm,
+						  priv->plane, NULL,
+						  NULL,
+						  NULL);
+	if (IS_ERR(priv->crtc))
+		return ERR_CAST(priv->crtc);
+
+	enc = &priv->encoder;
+	ret = drmm_encoder_init(drm, enc, NULL, DRM_MODE_ENCODER_TMDS, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+
+	enc->possible_crtcs = drm_crtc_mask(priv->crtc);
+
+	bridge = &priv->test_bridge->bridge;
+	bridge->type = DRM_MODE_CONNECTOR_HDMIA;
+	bridge->supported_formats = supported_formats;
+	bridge->max_bpc = max_bpc;
+	bridge->ops |= DRM_BRIDGE_OP_HDMI;
+	bridge->vendor = "LNX";
+	bridge->product = "KUnit";
+
+	ret = drm_kunit_bridge_add(test, bridge);
+	if (ret)
+		return ERR_PTR(ret);
+
+	ret = drm_bridge_attach(enc, bridge, NULL, 0);
+	if (ret)
+		return ERR_PTR(ret);
+
+	priv->connector = drm_bridge_connector_init(drm, enc);
+	if (IS_ERR(priv->connector))
+		return ERR_CAST(priv->connector);
+
+	drm_connector_attach_encoder(priv->connector, enc);
+
+	drm_mode_config_reset(drm);
+
+	return priv;
+}
+
 /*
  * Test that drm_bridge_get_current_state() returns the last committed
  * state for an atomic bridge.
@@ -786,10 +886,94 @@ static void drm_test_drm_bridge_helper_reset_crtc_legacy(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, bridge_priv->disable_count, 1);
 }
 
+/*
+ * Test that a bridge using the drm_atomic_helper_bridge_get_hdmi_output_bus_fmts()
+ * function for &drm_bridge_funcs.atomic_get_output_bus_fmts behaves as expected
+ * for an HDMI connector bridge. Does so by creating an HDMI bridge connector
+ * with RGB444, YCBCR444, and YCBCR420 (but not YCBCR422) as supported formats,
+ * sets the output depth to 8 bits per component, and then validates the returned
+ * list of bus formats.
+ */
+static void drm_test_drm_bridge_helper_hdmi_output_bus_fmts(struct kunit *test)
+{
+	struct drm_connector_state *conn_state;
+	struct drm_bridge_state *bridge_state;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_bridge_init_priv *priv;
+	struct drm_crtc_state *crtc_state;
+	struct drm_atomic_state *state;
+	struct drm_display_mode *mode;
+	unsigned int num_output_fmts;
+	struct drm_bridge *bridge;
+	u32 *out_bus_fmts;
+	int ret;
+
+	priv = drm_test_bridge_hdmi_init(test, &drm_test_bridge_bus_fmts_funcs,
+					 BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+					 BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444) |
+					 BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420),
+					 12);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+
+	bridge = &priv->test_bridge->bridge;
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	state = drm_kunit_helper_atomic_state_alloc(test, &priv->drm, &ctx);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+retry_commit:
+	conn_state = drm_atomic_get_connector_state(state, priv->connector);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	conn_state->hdmi.output_bpc = 8;
+
+	mode = drm_kunit_display_mode_from_cea_vic(test, &priv->drm, 16);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, mode);
+
+	ret = drm_atomic_set_crtc_for_connector(conn_state, priv->crtc);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state = drm_atomic_get_crtc_state(state, priv->crtc);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
+
+	ret = drm_atomic_set_mode_for_crtc(crtc_state, mode);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state->enable = true;
+	crtc_state->active = true;
+
+	bridge_state = drm_atomic_get_bridge_state(state, bridge);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bridge_state);
+
+	out_bus_fmts = bridge->funcs->atomic_get_output_bus_fmts(
+		bridge, bridge_state, crtc_state, conn_state, &num_output_fmts);
+	KUNIT_EXPECT_NOT_NULL(test, out_bus_fmts);
+	KUNIT_EXPECT_EQ(test, num_output_fmts, 3);
+
+	KUNIT_EXPECT_EQ(test, out_bus_fmts[0], MEDIA_BUS_FMT_RGB888_1X24);
+	KUNIT_EXPECT_EQ(test, out_bus_fmts[1], MEDIA_BUS_FMT_YUV8_1X24);
+	KUNIT_EXPECT_EQ(test, out_bus_fmts[2], MEDIA_BUS_FMT_UYYVYY8_0_5X24);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+
+	kfree(out_bus_fmts);
+}
+
 static struct kunit_case drm_bridge_helper_reset_crtc_tests[] = {
 	KUNIT_CASE(drm_test_drm_bridge_helper_reset_crtc_atomic),
 	KUNIT_CASE(drm_test_drm_bridge_helper_reset_crtc_atomic_disabled),
 	KUNIT_CASE(drm_test_drm_bridge_helper_reset_crtc_legacy),
+	KUNIT_CASE(drm_test_drm_bridge_helper_hdmi_output_bus_fmts),
 	{ }
 };
 

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 21/25] drm/tests: hdmi: Add tests for HDMI helper's mode_valid
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

Add some KUnit tests to verify that the HDMI state helper's mode_valid
implementation does not improperly reject chroma subsampled modes on the
basis of their clock rate not being satisfiable in RGB.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c | 109 +++++++++++++++++++++
 1 file changed, 109 insertions(+)

diff --git a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
index 3444c93c615f..74c9933eabfc 100644
--- a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
+++ b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
@@ -77,6 +77,23 @@ static struct drm_display_mode *find_420_only_mode(struct drm_connector *connect
 	return NULL;
 }
 
+static struct drm_display_mode *find_420_also_mode(struct drm_connector *connector)
+{
+	struct drm_device *drm = connector->dev;
+	struct drm_display_mode *mode;
+
+	mutex_lock(&drm->mode_config.mutex);
+	list_for_each_entry(mode, &connector->modes, head) {
+		if (drm_mode_is_420_also(&connector->display_info, mode)) {
+			mutex_unlock(&drm->mode_config.mutex);
+			return mode;
+		}
+	}
+	mutex_unlock(&drm->mode_config.mutex);
+
+	return NULL;
+}
+
 static int set_connector_edid(struct kunit *test, struct drm_connector *connector,
 			      const void *edid, size_t edid_len)
 {
@@ -2745,11 +2762,103 @@ static void drm_test_check_mode_valid_reject_max_clock(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, preferred->clock, 25200);
 }
 
+/*
+ * Test that drm_hdmi_connector_mode_valid() will accept modes that require a
+ * 4:2:0 chroma subsampling, even if said mode would violate maximum clock
+ * constraints if it used RGB 4:4:4.
+ */
+static void drm_test_check_mode_valid_yuv420_only_max_clock(struct kunit *test)
+{
+	struct drm_atomic_helper_connector_hdmi_priv *priv;
+	struct drm_display_mode *dank;
+	struct drm_connector *conn;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				BIT(HDMI_COLORSPACE_RGB) |
+				BIT(HDMI_COLORSPACE_YUV420),
+				8,
+				&dummy_connector_hdmi_funcs,
+				test_edid_hdmi_1080p_rgb_yuv_4k_yuv420_dc_max_200mhz);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	conn = &priv->connector;
+	KUNIT_ASSERT_EQ(test, conn->display_info.max_tmds_clock, 200 * 1000);
+
+	dank = find_420_only_mode(conn);
+	KUNIT_ASSERT_NOT_NULL(test, dank);
+	KUNIT_EXPECT_EQ(test, dank->hdisplay, 3840);
+	KUNIT_EXPECT_EQ(test, dank->vdisplay, 2160);
+
+	/*
+	 * Note: The mode's "clock" here is not accurate to the actual TMDS
+	 * clock that HDMI will use for a subsampled mode. Hence, why the mode's
+	 * clock is above the .max_tmds_clock of 200MHz.
+	 */
+	KUNIT_EXPECT_EQ(test, dank->clock, 297000);
+}
+
+/*
+ * Test that drm_hdmi_connector_mode_valid() will reject modes that require
+ * 4:2:0 chroma subsampling, if the connector does not support 4:2:0.
+ */
+static void
+drm_test_check_mode_valid_reject_yuv420_only_connector(struct kunit *test)
+{
+	struct drm_atomic_helper_connector_hdmi_priv *priv;
+	struct drm_display_mode *dank;
+	struct drm_connector *conn;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				BIT(HDMI_COLORSPACE_RGB),
+				8,
+				&dummy_connector_hdmi_funcs,
+				test_edid_hdmi_1080p_rgb_yuv_4k_yuv420_dc_max_200mhz);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	conn = &priv->connector;
+	KUNIT_ASSERT_EQ(test, conn->display_info.max_tmds_clock, 200 * 1000);
+
+	dank = find_420_only_mode(conn);
+	KUNIT_EXPECT_NULL(test, dank);
+}
+
+/*
+ * Test that drm_hdmi_connector_mode_valid() will accept modes that allow (among
+ * other color formats) 4:2:0 chroma subsampling, even if the connector does not
+ * support 4:2:0, but the mode's clock works for RGB 4:4:4.
+ */
+static void
+drm_test_check_mode_valid_accept_yuv420_also_connector_rgb(struct kunit *test)
+{
+	struct drm_atomic_helper_connector_hdmi_priv *priv;
+	struct drm_display_mode *mode;
+	struct drm_connector *conn;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				BIT(HDMI_COLORSPACE_RGB),
+				8,
+				&dummy_connector_hdmi_funcs,
+				test_edid_hdmi_4k_rgb_yuv420_dc_max_340mhz);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	conn = &priv->connector;
+	KUNIT_ASSERT_EQ(test, conn->display_info.max_tmds_clock, 340 * 1000);
+
+	mode = find_420_also_mode(conn);
+	KUNIT_ASSERT_NOT_NULL(test, mode);
+	KUNIT_EXPECT_EQ(test, mode->hdisplay, 3840);
+	KUNIT_EXPECT_EQ(test, mode->vdisplay, 2160);
+	KUNIT_EXPECT_EQ(test, mode->clock, 297000);
+}
+
 static struct kunit_case drm_atomic_helper_connector_hdmi_mode_valid_tests[] = {
 	KUNIT_CASE(drm_test_check_mode_valid),
 	KUNIT_CASE(drm_test_check_mode_valid_reject),
 	KUNIT_CASE(drm_test_check_mode_valid_reject_rate),
 	KUNIT_CASE(drm_test_check_mode_valid_reject_max_clock),
+	KUNIT_CASE(drm_test_check_mode_valid_yuv420_only_max_clock),
+	KUNIT_CASE(drm_test_check_mode_valid_reject_yuv420_only_connector),
+	KUNIT_CASE(drm_test_check_mode_valid_accept_yuv420_also_connector_rgb),
 	{ }
 };
 

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 25/25] drm/connector: Update docs of "colorspace" for color format prop
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

The colorspace property's documentation states that BT2020_RGB and
BT2020_YCC are equivalent, and the output format depends on the driver.

Now that there is a "color format" property that userspace can use to
explicitly set a format, update the colorspace docs to mention this.

The behaviour here is not changed for userspace that doesn't know about
the color format property yet, as the color format property defaults to
"AUTO", where the choice of output format is left up to drivers.

Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/drm_connector.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 0da136a93dd6..71c58fa15aa0 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -2573,7 +2573,8 @@ EXPORT_SYMBOL(drm_mode_create_aspect_ratio_property);
  *		conversion matrix and convert to the appropriate quantization
  *		range.
  *		The variants BT2020_RGB and BT2020_YCC are equivalent and the
- *		driver chooses between RGB and YCbCr on its own.
+ *		driver chooses between RGB and YCbCr based on the color format
+ *		property.
  *
  *	SMPTE_170M_YCC:
  *	BT709_YCC:

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 24/25] drm/bridge: Document bridge chain format selection
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

The bridge chain format selection behaviour was, until now,
undocumented. With the addition of the "color format" DRM property, it's
not sufficiently complex enough that documentation is warranted,
especially for driver authors trying to do the right thing.

Add a high-level overview of how the process is supposed to work, and
mention what the display driver is supposed to do if it wants to make
use of this functionality.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 Documentation/gpu/drm-kms-helpers.rst |  6 ++++++
 drivers/gpu/drm/drm_bridge.c          | 40 +++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/Documentation/gpu/drm-kms-helpers.rst b/Documentation/gpu/drm-kms-helpers.rst
index b4a9e5ae81f6..bf5a9d909cf3 100644
--- a/Documentation/gpu/drm-kms-helpers.rst
+++ b/Documentation/gpu/drm-kms-helpers.rst
@@ -169,6 +169,12 @@ Bridge Operations
 .. kernel-doc:: drivers/gpu/drm/drm_bridge.c
    :doc: bridge operations
 
+Bridge Chain Format Selection
+-----------------------------
+
+.. kernel-doc:: drivers/gpu/drm/drm_bridge.c
+   :doc: bridge chain format selection
+
 Bridge Connector Helper
 -----------------------
 
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 7c1516864d96..5cc7d281ef7f 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -198,6 +198,46 @@
  * driver.
  */
 
+/**
+ * DOC: bridge chain format selection
+ *
+ * A bridge chain, from display output processor to connector, may contain
+ * bridges capable of converting between bus formats on their inputs, and
+ * output formats on their outputs. For example, a bridge may be able to convert
+ * from RGB to YCbCr 4:4:4, and pass through YCbCr 4:2:0 as-is, but not convert
+ * from RGB to YCbCr 4:2:0. This means not all input formats map to all output
+ * formats.
+ *
+ * Further adding to this, a desired output color format, as specified with the
+ * "color format" DRM property, might not correspond 1:1 to what the display
+ * driver should set at its output. The bridge chain it feeds into may only be
+ * able to reach the desired output format, if a conversion from a different
+ * starting format is performed.
+ *
+ * To deal with this complexity, the recursive bridge chain bus format selection
+ * logic starts with the last bridge in the chain, usually the connector, and
+ * then recursively walks the chain of bridges backwards to the first bridge,
+ * trying to find a path.
+ *
+ * For a display driver to work in such a scenario, it should read the first
+ * bridge's bridge state to figure out which bus format the chain resolved to.
+ * If the first bridge's input format resolved to %MEDIA_BUS_FMT_FIXED, then its
+ * output format should be used.
+ *
+ * Special handling is done for HDMI as it relates to format selection. Instead
+ * of directly using the "color format" DRM property for bridge chains that end
+ * in HDMI bridges, the bridge chain format selection logic will trust the logic
+ * that set the HDMI output format. For the common HDMI state helper
+ * functionality, this means that %DRM_CONNECTOR_COLOR_FORMAT_AUTO will allow
+ * fallbacks to YCBCr 4:2:0 if the bandwidth requirements would otherwise be too
+ * high but the mode and connector allow it.
+ *
+ * For bridge chains that do not end in an HDMI bridge,
+ * %DRM_CONNECTOR_COLOR_FORMAT_AUTO will be satisfied with the first output
+ * format on the last bridge for which it can find a path back to the first
+ * bridge.
+ */
+
 /* Protect bridge_list and bridge_lingering_list */
 static DEFINE_MUTEX(bridge_lock);
 static LIST_HEAD(bridge_list);

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 22/25] drm/tests: bridge: Add KUnit tests for bridge chain format selection
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

With the "color format" property, the bridge chain format selection has
gained increased complexity. Instead of simply finding any sequence of
bus formats that works, the bridge chain format selection needs to pick
a sequence that results in the requested color format.

Add KUnit tests for this new logic. These take the form of some pleasant
preprocessor macros to make it less cumbersome to define test bridges
with a set of possible input and output formats.

The input and output formats are defined for bridges in the form of
tuples, where the first member defines the input format, and the second
member defines the output format that can be produced from this input
format. This means the tests can construct scenarios in which not all
inputs can be converted to all outputs.

Some tests are added to test interesting scenarios to exercise the bus
format selection in the presence of a specific color format request.

Furthermore, tests are added to verify that bridge chains that end in an
HDMI connector will always prefer RGB when the color format is
DRM_CONNECTOR_COLOR_FORMAT_AUTO, as is the behaviour in the HDMI state
helpers.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/tests/drm_bridge_test.c | 787 ++++++++++++++++++++++++++++++++
 1 file changed, 787 insertions(+)

diff --git a/drivers/gpu/drm/tests/drm_bridge_test.c b/drivers/gpu/drm/tests/drm_bridge_test.c
index 887020141c7f..cb821c606070 100644
--- a/drivers/gpu/drm/tests/drm_bridge_test.c
+++ b/drivers/gpu/drm/tests/drm_bridge_test.c
@@ -2,15 +2,23 @@
 /*
  * Kunit test for drm_bridge functions
  */
+#include <linux/cleanup.h>
+#include <linux/media-bus-format.h>
+
 #include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_atomic_uapi.h>
 #include <drm/drm_bridge.h>
 #include <drm/drm_bridge_connector.h>
 #include <drm/drm_bridge_helper.h>
+#include <drm/drm_edid.h>
 #include <drm/drm_kunit_helpers.h>
+#include <drm/drm_managed.h>
 
 #include <kunit/device.h>
 #include <kunit/test.h>
 
+#include "drm_kunit_edid.h"
+
 /*
  * Mimick the typical "private" struct defined by a bridge driver, which
  * embeds a bridge plus other fields.
@@ -37,6 +45,21 @@ struct drm_bridge_init_priv {
 	bool destroyed;
 };
 
+struct drm_bridge_chain_priv {
+	struct drm_device drm;
+	struct drm_encoder encoder;
+	struct drm_plane *plane;
+	struct drm_crtc *crtc;
+	struct drm_connector *connector;
+	unsigned int num_bridges;
+
+	/**
+	 * @test_bridges: array of pointers to &struct drm_bridge_priv entries
+	 *                of which the first @num_bridges entries are valid.
+	 */
+	struct drm_bridge_priv **test_bridges;
+};
+
 static struct drm_bridge_priv *bridge_to_priv(struct drm_bridge *bridge)
 {
 	return container_of(bridge, struct drm_bridge_priv, bridge);
@@ -95,6 +118,229 @@ static const struct drm_bridge_funcs drm_test_bridge_atomic_funcs = {
 	.atomic_reset		= drm_atomic_helper_bridge_reset,
 };
 
+/**
+ * struct fmt_tuple - a tuple of input/output MEDIA_BUS_FMT_*
+ */
+struct fmt_tuple {
+	u32 in_fmt;
+	u32 out_fmt;
+};
+
+/*
+ * Format mapping that only accepts RGB888, and outputs only RGB888
+ */
+static const struct fmt_tuple rgb8_passthrough[] = {
+	{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_RGB888_1X24 },
+};
+
+/*
+ * Format mapping that only accepts YUV444, and outputs only YUV444
+ */
+static const struct fmt_tuple yuv8_passthrough[] = {
+	{ MEDIA_BUS_FMT_YUV8_1X24,   MEDIA_BUS_FMT_YUV8_1X24 },
+};
+
+/*
+ * Format mapping where 8bpc RGB -> 8bpc YUV444, or ID(RGB) or ID(YUV444)
+ */
+static const struct fmt_tuple rgb8_to_yuv8_or_id[] = {
+	{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_RGB888_1X24 },
+	{ MEDIA_BUS_FMT_YUV8_1X24,   MEDIA_BUS_FMT_YUV8_1X24 },
+	{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_YUV8_1X24 },
+};
+
+static const struct fmt_tuple rgb8_to_id_yuv8_or_yuv8_to_yuv422_yuv420[] = {
+	{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_RGB888_1X24 },
+	{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_YUV8_1X24 },
+	{ MEDIA_BUS_FMT_YUV8_1X24,   MEDIA_BUS_FMT_UYVY8_1X16 },
+	{ MEDIA_BUS_FMT_YUV8_1X24,   MEDIA_BUS_FMT_UYYVYY8_0_5X24 },
+};
+
+/*
+ * Format mapping where 8bpc YUV444 -> 8bpc RGB, or ID(YUV444)
+ */
+static const struct fmt_tuple yuv8_to_rgb8_or_id[] = {
+	{ MEDIA_BUS_FMT_YUV8_1X24, MEDIA_BUS_FMT_YUV8_1X24 },
+	{ MEDIA_BUS_FMT_YUV8_1X24, MEDIA_BUS_FMT_RGB888_1X24 },
+};
+
+/*
+ * A format mapping that acts like a video processor that generates an RGB signal
+ */
+static const struct fmt_tuple rgb_producer[] = {
+	{ MEDIA_BUS_FMT_FIXED, MEDIA_BUS_FMT_RGB888_1X24 },
+	{ MEDIA_BUS_FMT_FIXED, MEDIA_BUS_FMT_RGB101010_1X30 },
+	{ MEDIA_BUS_FMT_FIXED, MEDIA_BUS_FMT_RGB121212_1X36 },
+};
+
+/*
+ * A format mapping that acts like a video processor that generates an 8-bit RGB,
+ * YUV444 or YUV420 signal
+ */
+static const struct fmt_tuple rgb_yuv444_yuv420_producer[] = {
+	{ MEDIA_BUS_FMT_FIXED, MEDIA_BUS_FMT_RGB888_1X24 },
+	{ MEDIA_BUS_FMT_FIXED, MEDIA_BUS_FMT_YUV8_1X24 },
+	{ MEDIA_BUS_FMT_FIXED, MEDIA_BUS_FMT_UYYVYY8_0_5X24 },
+};
+
+static const struct fmt_tuple rgb8_yuv444_yuv422_passthrough[] = {
+	{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_RGB888_1X24 },
+	{ MEDIA_BUS_FMT_YUV8_1X24,   MEDIA_BUS_FMT_YUV8_1X24 },
+	{ MEDIA_BUS_FMT_UYVY8_1X16,  MEDIA_BUS_FMT_UYVY8_1X16 },
+};
+
+static const struct fmt_tuple yuv444_yuv422_rgb8_passthrough[] = {
+	{ MEDIA_BUS_FMT_YUV8_1X24,   MEDIA_BUS_FMT_YUV8_1X24 },
+	{ MEDIA_BUS_FMT_UYVY8_1X16,  MEDIA_BUS_FMT_UYVY8_1X16 },
+	{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_RGB888_1X24 },
+};
+
+static bool fmt_in_list(const u32 fmt, const u32 *out_fmts, const size_t num_fmts)
+{
+	size_t i;
+
+	for (i = 0; i < num_fmts; i++)
+		if (out_fmts[i] == fmt)
+			return true;
+
+	return false;
+}
+
+/**
+ * get_tuples_out_fmts - Get unique output formats of a &struct fmt_tuple list
+ * @fmt_tuples: array of &struct fmt_tuple
+ * @num_fmt_tuples: number of entries in @fmt_tuples
+ * @out_fmts: target array to store the unique output bus formats
+ *
+ * Returns the number of unique output formats, i.e. the number of entries in
+ * @out_fmts that were populated with sensible values.
+ */
+static size_t get_tuples_out_fmts(const struct fmt_tuple *fmt_tuples,
+				  const size_t num_fmt_tuples, u32 *out_fmts)
+{
+	size_t num_unique = 0;
+	size_t i;
+
+	for (i = 0; i < num_fmt_tuples; i++)
+		if (!fmt_in_list(fmt_tuples[i].out_fmt, out_fmts, num_unique))
+			out_fmts[num_unique++] = fmt_tuples[i].out_fmt;
+
+	return num_unique;
+}
+
+#define DEFINE_FMT_FUNCS_FROM_TUPLES(name) \
+static u32 *drm_test_bridge_ ## name ## _out_fmts(struct drm_bridge *bridge,			\
+						  struct drm_bridge_state *bridge_state,	\
+						  struct drm_crtc_state *crtc_state,		\
+						  struct drm_connector_state *conn_state,	\
+						  unsigned int *num_output_fmts)		\
+{												\
+	u32 *out_fmts = kcalloc(ARRAY_SIZE((name)), sizeof(u32), GFP_KERNEL);			\
+												\
+	if (out_fmts)										\
+		*num_output_fmts = get_tuples_out_fmts((name), ARRAY_SIZE((name)), out_fmts);	\
+	else											\
+		*num_output_fmts = 0;								\
+												\
+	return out_fmts;									\
+}												\
+												\
+static u32 *drm_test_bridge_ ## name ## _in_fmts(struct drm_bridge *bridge,			\
+						 struct drm_bridge_state *bridge_state,		\
+						 struct drm_crtc_state *crtc_state,		\
+						 struct drm_connector_state *conn_state,	\
+						 u32 output_fmt,				\
+						 unsigned int *num_input_fmts)			\
+{												\
+	u32 *in_fmts = kcalloc(ARRAY_SIZE((name)), sizeof(u32), GFP_KERNEL);			\
+	unsigned int num_fmts = 0;								\
+	size_t i;										\
+												\
+	if (!in_fmts) {										\
+		*num_input_fmts = 0;								\
+		return NULL;									\
+	}											\
+												\
+	for (i = 0; i < ARRAY_SIZE((name)); i++)						\
+		if ((name)[i].out_fmt == output_fmt)						\
+			in_fmts[num_fmts++] = (name)[i].in_fmt;					\
+												\
+	*num_input_fmts = num_fmts;								\
+												\
+	return in_fmts;										\
+}
+
+#define DRM_BRIDGE_ATOMIC_WITH_BUS_FMT_HDMI_FUNC(ident, input_fmts_func, output_fmts_func,	\
+						 hdmi_write_infoframe_func,			\
+						 hdmi_clear_infoframe_func)			\
+static const struct drm_bridge_funcs (ident) = {						\
+	.atomic_enable			= drm_test_bridge_atomic_enable,			\
+	.atomic_disable			= drm_test_bridge_atomic_disable,			\
+	.atomic_destroy_state		= drm_atomic_helper_bridge_destroy_state,		\
+	.atomic_duplicate_state		= drm_atomic_helper_bridge_duplicate_state,		\
+	.atomic_reset			= drm_atomic_helper_bridge_reset,			\
+	.atomic_get_input_bus_fmts	= (input_fmts_func),					\
+	.atomic_get_output_bus_fmts	= (output_fmts_func),					\
+	.hdmi_write_avi_infoframe	= (hdmi_write_infoframe_func),				\
+	.hdmi_clear_avi_infoframe	= (hdmi_clear_infoframe_func),				\
+	.hdmi_write_hdmi_infoframe	= (hdmi_write_infoframe_func),				\
+	.hdmi_clear_hdmi_infoframe	= (hdmi_clear_infoframe_func),				\
+}
+
+#define DRM_BRIDGE_ATOMIC_WITH_BUS_FMT_FUNC(ident, input_fmts_func, output_fmts_func)		\
+	DRM_BRIDGE_ATOMIC_WITH_BUS_FMT_HDMI_FUNC(ident, input_fmts_func, output_fmts_func,	\
+						 NULL, NULL)
+
+#define DRM_BRIDGE_ATOMIC_WITH_BUS_FMT(_name)						\
+	DRM_BRIDGE_ATOMIC_WITH_BUS_FMT_FUNC(_name ## _funcs,				\
+					    drm_test_bridge_ ## _name ## _in_fmts,	\
+					    drm_test_bridge_ ## _name ## _out_fmts)
+
+static int drm_test_bridge_write_infoframe_stub(struct drm_bridge *bridge,
+						const u8 *buffer, size_t len)
+{
+	return 0;
+}
+
+static int drm_test_bridge_clear_infoframe_stub(struct drm_bridge *bridge)
+{
+	return 0;
+}
+
+#define DRM_BRIDGE_ATOMIC_WITH_BUS_FMT_HDMI(_name)						\
+	DRM_BRIDGE_ATOMIC_WITH_BUS_FMT_HDMI_FUNC(_name ## _hdmi ## _funcs,			\
+						 drm_test_bridge_ ## _name ## _in_fmts,		\
+						 drm_test_bridge_ ## _name ## _out_fmts,	\
+						 drm_test_bridge_write_infoframe_stub,		\
+						 drm_test_bridge_clear_infoframe_stub)
+DEFINE_FMT_FUNCS_FROM_TUPLES(rgb8_passthrough)
+DRM_BRIDGE_ATOMIC_WITH_BUS_FMT(rgb8_passthrough);
+
+DEFINE_FMT_FUNCS_FROM_TUPLES(yuv8_passthrough)
+DRM_BRIDGE_ATOMIC_WITH_BUS_FMT(yuv8_passthrough);
+
+DEFINE_FMT_FUNCS_FROM_TUPLES(rgb8_to_yuv8_or_id)
+DRM_BRIDGE_ATOMIC_WITH_BUS_FMT(rgb8_to_yuv8_or_id);
+
+DEFINE_FMT_FUNCS_FROM_TUPLES(yuv8_to_rgb8_or_id)
+DRM_BRIDGE_ATOMIC_WITH_BUS_FMT(yuv8_to_rgb8_or_id);
+
+DEFINE_FMT_FUNCS_FROM_TUPLES(rgb_producer)
+DRM_BRIDGE_ATOMIC_WITH_BUS_FMT(rgb_producer);
+
+DEFINE_FMT_FUNCS_FROM_TUPLES(rgb_yuv444_yuv420_producer)
+DRM_BRIDGE_ATOMIC_WITH_BUS_FMT(rgb_yuv444_yuv420_producer);
+
+DEFINE_FMT_FUNCS_FROM_TUPLES(rgb8_to_id_yuv8_or_yuv8_to_yuv422_yuv420)
+DRM_BRIDGE_ATOMIC_WITH_BUS_FMT(rgb8_to_id_yuv8_or_yuv8_to_yuv422_yuv420);
+
+DEFINE_FMT_FUNCS_FROM_TUPLES(rgb8_yuv444_yuv422_passthrough)
+DRM_BRIDGE_ATOMIC_WITH_BUS_FMT(rgb8_yuv444_yuv422_passthrough);
+
+DEFINE_FMT_FUNCS_FROM_TUPLES(yuv444_yuv422_rgb8_passthrough)
+DRM_BRIDGE_ATOMIC_WITH_BUS_FMT(yuv444_yuv422_rgb8_passthrough);
+DRM_BRIDGE_ATOMIC_WITH_BUS_FMT_HDMI(yuv444_yuv422_rgb8_passthrough);
+
 KUNIT_DEFINE_ACTION_WRAPPER(drm_bridge_remove_wrapper,
 			    drm_bridge_remove,
 			    struct drm_bridge *);
@@ -180,6 +426,119 @@ drm_test_bridge_init(struct kunit *test, const struct drm_bridge_funcs *funcs)
 	return priv;
 }
 
+static struct drm_bridge_chain_priv *
+drm_test_bridge_chain_init(struct kunit *test, unsigned int num_bridges,
+			   const struct drm_bridge_funcs **funcs)
+{
+	struct drm_bridge_chain_priv *priv;
+	const struct drm_edid *edid;
+	struct drm_bridge *prev;
+	struct drm_encoder *enc;
+	struct drm_bridge *bridge;
+	struct drm_device *drm;
+	bool has_hdmi = false;
+	struct device *dev;
+	unsigned int i;
+	int ret;
+
+	dev = drm_kunit_helper_alloc_device(test);
+	if (IS_ERR(dev))
+		return ERR_CAST(dev);
+
+	priv = drm_kunit_helper_alloc_drm_device(test, dev, struct drm_bridge_chain_priv,
+						 drm, DRIVER_MODESET | DRIVER_ATOMIC);
+	if (IS_ERR(priv))
+		return ERR_CAST(priv);
+
+	drm = &priv->drm;
+
+	priv->test_bridges = drmm_kmalloc_array(drm, num_bridges, sizeof(*priv->test_bridges),
+						GFP_KERNEL);
+	if (!priv->test_bridges)
+		return ERR_PTR(-ENOMEM);
+
+	priv->num_bridges = num_bridges;
+
+	for (i = 0; i < num_bridges; i++) {
+		priv->test_bridges[i] = devm_drm_bridge_alloc(dev, struct drm_bridge_priv,
+							      bridge, funcs[i]);
+		if (IS_ERR(priv->test_bridges[i]))
+			return ERR_CAST(priv->test_bridges[i]);
+
+		priv->test_bridges[i]->data = priv;
+	}
+
+	priv->plane = drm_kunit_helper_create_primary_plane(test, drm, NULL, NULL,
+							    NULL, 0, NULL);
+	if (IS_ERR(priv->plane))
+		return ERR_CAST(priv->plane);
+
+	priv->crtc = drm_kunit_helper_create_crtc(test, drm, priv->plane, NULL,
+						  NULL, NULL);
+	if (IS_ERR(priv->crtc))
+		return ERR_CAST(priv->crtc);
+
+	enc = &priv->encoder;
+	ret = drmm_encoder_init(drm, enc, NULL, DRM_MODE_ENCODER_TMDS, NULL);
+	if (ret)
+		return ERR_PTR(ret);
+
+	enc->possible_crtcs = drm_crtc_mask(priv->crtc);
+
+	prev = NULL;
+	for (i = 0; i < num_bridges; i++) {
+		bridge = &priv->test_bridges[i]->bridge;
+		bridge->type = DRM_MODE_CONNECTOR_VIRTUAL;
+
+		if (bridge->funcs->hdmi_write_hdmi_infoframe) {
+			has_hdmi = true;
+			bridge->ops |= DRM_BRIDGE_OP_HDMI;
+			bridge->type = DRM_MODE_CONNECTOR_HDMIA;
+			bridge->vendor = "LNX";
+			bridge->product = "KUnit";
+			bridge->supported_formats = (BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+						     BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444) |
+						     BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422) |
+						     BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420));
+		}
+
+		ret = drm_kunit_bridge_add(test, bridge);
+		if (ret)
+			return ERR_PTR(ret);
+
+		ret = drm_bridge_attach(enc, bridge, prev, 0);
+		if (ret)
+			return ERR_PTR(ret);
+
+		prev = bridge;
+	}
+
+	priv->connector = drm_bridge_connector_init(drm, enc);
+	if (IS_ERR(priv->connector))
+		return ERR_CAST(priv->connector);
+
+	drm_connector_attach_encoder(priv->connector, enc);
+
+	drm_mode_config_reset(drm);
+
+	if (!has_hdmi)
+		return priv;
+
+	scoped_guard(mutex, &drm->mode_config.mutex) {
+		edid = drm_edid_alloc(test_edid_hdmi_1080p_rgb_yuv_4k_yuv420_dc_max_200mhz,
+				ARRAY_SIZE(test_edid_hdmi_1080p_rgb_yuv_4k_yuv420_dc_max_200mhz));
+		if (!edid)
+			return ERR_PTR(-EINVAL);
+
+		drm_edid_connector_update(priv->connector, edid);
+		KUNIT_ASSERT_GT(test, drm_edid_connector_add_modes(priv->connector), 0);
+
+		ret = priv->connector->funcs->fill_modes(priv->connector, 4096, 4096);
+	}
+
+	return priv;
+}
+
 /*
  * Test that drm_bridge_get_current_state() returns the last committed
  * state for an atomic bridge.
@@ -508,14 +867,442 @@ static struct kunit_suite drm_bridge_alloc_test_suite = {
 	.test_cases = drm_bridge_alloc_tests,
 };
 
+/**
+ * drm_test_bridge_chain_verify_fmt - Verify bridge chain format selection
+ * @test: pointer to KUnit test object
+ * @priv: pointer to a &struct drm_bridge_chain_priv for this chain
+ * @expected: constant array of &struct fmt_tuple describing the expected
+ *            input and output bus formats
+ * @num_expected: number of entries in @expected
+ *
+ * Runs the KUNIT_EXPECT clauses to verify the bridge chain format selection
+ * resulted in the expected formats. If %0 is given as a format in a
+ * &struct fmt_tuple, then it is understood to mean "any".
+ *
+ * Must be called with the modeset lock held.
+ */
+static void drm_test_bridge_chain_verify_fmt(struct kunit *test,
+					     struct drm_bridge_chain_priv *priv,
+					     const struct fmt_tuple *const expected,
+					     const unsigned int num_expected)
+{
+	struct drm_bridge_state *bstate;
+	unsigned int i = 0;
+
+	drm_for_each_bridge_in_chain_scoped(&priv->encoder, bridge) {
+		KUNIT_ASSERT_LT(test, i, num_expected);
+
+		bstate = drm_bridge_get_current_state(bridge);
+		if (expected[i].in_fmt)
+			KUNIT_EXPECT_EQ(test, bstate->input_bus_cfg.format,
+					expected[i].in_fmt);
+		if (expected[i].out_fmt)
+			KUNIT_EXPECT_EQ(test, bstate->output_bus_cfg.format,
+					expected[i].out_fmt);
+
+		i++;
+	}
+
+	KUNIT_ASSERT_EQ_MSG(test, i, num_expected,
+			    "Fewer bridges (%u) than expected (%u)\n", i, num_expected);
+}
+
+/*
+ * Test that constructs a bridge chain in which an RGB888 producer is chained to
+ * two bridges that will convert from RGB to YUV and from YUV to RGB respectively.
+ *
+ * The test requests an output color_format of RGB using the color_format property,
+ * so to satisfy this request, the bridge chain must take a detour over YUV.
+ */
+static void drm_test_bridge_rgb_yuv_rgb(struct kunit *test)
+{
+	static const struct drm_bridge_funcs *funcs[] = {
+		&rgb_producer_funcs,
+		&rgb8_to_yuv8_or_id_funcs,
+		&yuv8_to_rgb8_or_id_funcs,
+	};
+	static const struct fmt_tuple expected[] = {
+		{ MEDIA_BUS_FMT_FIXED, MEDIA_BUS_FMT_RGB888_1X24 },
+		{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_YUV8_1X24 },
+		{ MEDIA_BUS_FMT_YUV8_1X24, MEDIA_BUS_FMT_RGB888_1X24 },
+	};
+	struct drm_connector_state *conn_state;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_bridge_chain_priv *priv;
+	struct drm_crtc_state *crtc_state;
+	struct drm_atomic_state *state;
+	struct drm_display_mode *mode;
+	int ret;
+
+	priv = drm_test_bridge_chain_init(test, ARRAY_SIZE(funcs), funcs);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	state = drm_kunit_helper_atomic_state_alloc(test, &priv->drm, &ctx);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+retry_commit:
+	conn_state = drm_atomic_get_connector_state(state, priv->connector);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	mode = drm_kunit_display_mode_from_cea_vic(test, &priv->drm, 16);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, mode);
+
+	conn_state->color_format = DRM_CONNECTOR_COLOR_FORMAT_RGB444;
+
+	ret = drm_atomic_set_crtc_for_connector(conn_state, priv->crtc);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state = drm_atomic_get_crtc_state(state, priv->crtc);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
+
+	ret = drm_atomic_set_mode_for_crtc(crtc_state, mode);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state->enable = true;
+	crtc_state->active = true;
+
+	ret = drm_atomic_commit(state);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	drm_test_bridge_chain_verify_fmt(test, priv, expected, ARRAY_SIZE(expected));
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
+/*
+ * Test in which a bridge capable of producing RGB, YUV444 and YUV420 has to
+ * produce RGB and convert with a downstream bridge in the chain to reach the
+ * requested YUV444 color format, as no direct path exists between its YUV444
+ * and the last bridge.
+ *
+ * The rationale behind this test is to devise a scenario in which naively
+ * assuming any format the video processor can output, and the connector
+ * requests, is the right format to pick, does not work.
+ */
+static void drm_test_bridge_must_convert_to_yuv444(struct kunit *test)
+{
+	static const struct drm_bridge_funcs *funcs[] = {
+		&rgb_yuv444_yuv420_producer_funcs,
+		&rgb8_passthrough_funcs,
+		&rgb8_to_id_yuv8_or_yuv8_to_yuv422_yuv420_funcs,
+		&rgb8_yuv444_yuv422_passthrough_funcs,
+	};
+	static const struct fmt_tuple expected[] = {
+		{ MEDIA_BUS_FMT_FIXED, MEDIA_BUS_FMT_RGB888_1X24 },
+		{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_RGB888_1X24 },
+		{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_YUV8_1X24 },
+		{ MEDIA_BUS_FMT_YUV8_1X24, MEDIA_BUS_FMT_YUV8_1X24 },
+	};
+	struct drm_connector_state *conn_state;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_bridge_chain_priv *priv;
+	struct drm_crtc_state *crtc_state;
+	struct drm_atomic_state *state;
+	struct drm_display_mode *mode;
+	int ret;
+
+	priv = drm_test_bridge_chain_init(test, ARRAY_SIZE(funcs), funcs);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	state = drm_kunit_helper_atomic_state_alloc(test, &priv->drm, &ctx);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+retry_commit:
+	conn_state = drm_atomic_get_connector_state(state, priv->connector);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	mode = drm_kunit_display_mode_from_cea_vic(test, &priv->drm, 16);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, mode);
+
+	conn_state->color_format = DRM_CONNECTOR_COLOR_FORMAT_YCBCR444;
+
+	ret = drm_atomic_set_crtc_for_connector(conn_state, priv->crtc);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state = drm_atomic_get_crtc_state(state, priv->crtc);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
+
+	ret = drm_atomic_set_mode_for_crtc(crtc_state, mode);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state->enable = true;
+	crtc_state->active = true;
+
+	ret = drm_atomic_commit(state);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	drm_test_bridge_chain_verify_fmt(test, priv, expected, ARRAY_SIZE(expected));
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
+/*
+ * Test which checks that no matter the order of bus formats returned by an
+ * HDMI bridge, RGB is preferred on DRM_CONNECTOR_COLOR_FORMAT_AUTO if it's
+ * available.
+ */
+static void drm_test_bridge_hdmi_auto_rgb(struct kunit *test)
+{
+	static const struct drm_bridge_funcs *funcs[] = {
+		&rgb_yuv444_yuv420_producer_funcs,
+		&yuv444_yuv422_rgb8_passthrough_hdmi_funcs,
+	};
+	static const struct fmt_tuple expected[] = {
+		{ MEDIA_BUS_FMT_FIXED, MEDIA_BUS_FMT_RGB888_1X24 },
+		{ MEDIA_BUS_FMT_RGB888_1X24, MEDIA_BUS_FMT_RGB888_1X24 },
+	};
+	struct drm_connector_state *conn_state;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_bridge_chain_priv *priv;
+	struct drm_crtc_state *crtc_state;
+	struct drm_atomic_state *state;
+	struct drm_display_mode *mode;
+	int ret;
+
+	priv = drm_test_bridge_chain_init(test, ARRAY_SIZE(funcs), funcs);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	state = drm_kunit_helper_atomic_state_alloc(test, &priv->drm, &ctx);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+retry_commit:
+	conn_state = drm_atomic_get_connector_state(state, priv->connector);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	mode = drm_kunit_display_mode_from_cea_vic(test, &priv->drm, 16);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, mode);
+
+	KUNIT_ASSERT_EQ(test, conn_state->color_format, DRM_CONNECTOR_COLOR_FORMAT_AUTO);
+
+	ret = drm_atomic_set_crtc_for_connector(conn_state, priv->crtc);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state = drm_atomic_get_crtc_state(state, priv->crtc);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
+
+	ret = drm_atomic_set_mode_for_crtc(crtc_state, mode);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state->enable = true;
+	crtc_state->active = true;
+
+	ret = drm_atomic_commit(state);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, DRM_OUTPUT_COLOR_FORMAT_RGB444);
+
+	drm_test_bridge_chain_verify_fmt(test, priv, expected, ARRAY_SIZE(expected));
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
+/*
+ * Test which checks that DRM_CONNECTOR_COLOR_FORMAT_AUTO on non-HDMI connectors
+ * will result in the first bus format on the output to be picked.
+ */
+static void drm_test_bridge_auto_first(struct kunit *test)
+{
+	static const struct drm_bridge_funcs *funcs[] = {
+		&rgb_yuv444_yuv420_producer_funcs,
+		&yuv444_yuv422_rgb8_passthrough_funcs,
+	};
+	static const struct fmt_tuple expected[] = {
+		{ MEDIA_BUS_FMT_FIXED, MEDIA_BUS_FMT_YUV8_1X24 },
+		{ MEDIA_BUS_FMT_YUV8_1X24, MEDIA_BUS_FMT_YUV8_1X24 },
+	};
+	struct drm_connector_state *conn_state;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_bridge_chain_priv *priv;
+	struct drm_crtc_state *crtc_state;
+	struct drm_atomic_state *state;
+	struct drm_display_mode *mode;
+	int ret;
+
+	priv = drm_test_bridge_chain_init(test, ARRAY_SIZE(funcs), funcs);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	state = drm_kunit_helper_atomic_state_alloc(test, &priv->drm, &ctx);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+retry_commit:
+	conn_state = drm_atomic_get_connector_state(state, priv->connector);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	mode = drm_kunit_display_mode_from_cea_vic(test, &priv->drm, 16);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, mode);
+
+	KUNIT_ASSERT_EQ(test, conn_state->color_format, DRM_CONNECTOR_COLOR_FORMAT_AUTO);
+
+	ret = drm_atomic_set_crtc_for_connector(conn_state, priv->crtc);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state = drm_atomic_get_crtc_state(state, priv->crtc);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
+
+	ret = drm_atomic_set_mode_for_crtc(crtc_state, mode);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state->enable = true;
+	crtc_state->active = true;
+
+	ret = drm_atomic_commit(state);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	drm_test_bridge_chain_verify_fmt(test, priv, expected, ARRAY_SIZE(expected));
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
+/*
+ * Test which checks that in a configuration of bridge chains where an RGB
+ * producer is hooked to a YUV444-only pass-through, the atomic commit fails as
+ * the bridge format selection cannot find a valid sequence of bus formats.
+ */
+static void drm_test_bridge_rgb_yuv_no_path(struct kunit *test)
+{
+	static const struct drm_bridge_funcs *funcs[] = {
+		&rgb_producer_funcs,
+		&yuv8_passthrough_funcs,
+		&rgb8_yuv444_yuv422_passthrough_funcs,
+	};
+	struct drm_connector_state *conn_state;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_bridge_chain_priv *priv;
+	struct drm_crtc_state *crtc_state;
+	struct drm_atomic_state *state;
+	struct drm_display_mode *mode;
+	int ret;
+
+	priv = drm_test_bridge_chain_init(test, ARRAY_SIZE(funcs), funcs);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	state = drm_kunit_helper_atomic_state_alloc(test, &priv->drm, &ctx);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+retry_commit:
+	conn_state = drm_atomic_get_connector_state(state, priv->connector);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	mode = drm_kunit_display_mode_from_cea_vic(test, &priv->drm, 16);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, mode);
+
+	ret = drm_atomic_set_crtc_for_connector(conn_state, priv->crtc);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state = drm_atomic_get_crtc_state(state, priv->crtc);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
+
+	ret = drm_atomic_set_mode_for_crtc(crtc_state, mode);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state->enable = true;
+	crtc_state->active = true;
+
+	ret = drm_atomic_commit(state);
+	if (ret == -EDEADLK) {
+		drm_modeset_backoff(&ctx);
+		goto retry_commit;
+	}
+	KUNIT_EXPECT_EQ(test, ret, -ENOTSUPP);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
+static struct kunit_case drm_bridge_bus_fmt_tests[] = {
+	KUNIT_CASE(drm_test_bridge_rgb_yuv_rgb),
+	KUNIT_CASE(drm_test_bridge_must_convert_to_yuv444),
+	KUNIT_CASE(drm_test_bridge_hdmi_auto_rgb),
+	KUNIT_CASE(drm_test_bridge_auto_first),
+	KUNIT_CASE(drm_test_bridge_rgb_yuv_no_path),
+	{ }
+};
+
+static struct kunit_suite drm_bridge_bus_fmt_test_suite = {
+	.name = "drm_bridge_bus_fmt",
+	.test_cases = drm_bridge_bus_fmt_tests,
+};
+
 kunit_test_suites(
 	&drm_bridge_get_current_state_test_suite,
 	&drm_bridge_helper_reset_crtc_test_suite,
 	&drm_bridge_alloc_test_suite,
+	&drm_bridge_bus_fmt_test_suite,
 );
 
 MODULE_AUTHOR("Maxime Ripard <mripard@kernel.org>");
 MODULE_AUTHOR("Luca Ceresoli <luca.ceresoli@bootlin.com>");
+MODULE_AUTHOR("Nicolas Frattaroli <nicolas.frattaroli@collabora.com>");
 
 MODULE_DESCRIPTION("Kunit test for drm_bridge functions");
 MODULE_LICENSE("GPL");

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 20/25] drm/tests: hdmi: Add tests for the color_format property
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

Add some KUnit tests to check the color_format property is working as
expected with the HDMI state helper.

Existing tests are extended to also test the
DRM_CONNECTOR_COLOR_FORMAT_AUTO case, in order to avoid duplicating test
cases. For the explicitly selected color format cases, parameterized
tests are added.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c | 236 +++++++++++++++++++++
 1 file changed, 236 insertions(+)

diff --git a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
index a4357efaa983..3444c93c615f 100644
--- a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
+++ b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
@@ -60,6 +60,23 @@ static struct drm_display_mode *find_preferred_mode(struct drm_connector *connec
 	return preferred;
 }
 
+static struct drm_display_mode *find_420_only_mode(struct drm_connector *connector)
+{
+	struct drm_device *drm = connector->dev;
+	struct drm_display_mode *mode;
+
+	mutex_lock(&drm->mode_config.mutex);
+	list_for_each_entry(mode, &connector->modes, head) {
+		if (drm_mode_is_420_only(&connector->display_info, mode)) {
+			mutex_unlock(&drm->mode_config.mutex);
+			return mode;
+		}
+	}
+	mutex_unlock(&drm->mode_config.mutex);
+
+	return NULL;
+}
+
 static int set_connector_edid(struct kunit *test, struct drm_connector *connector,
 			      const void *edid, size_t edid_len)
 {
@@ -1547,6 +1564,7 @@ static void drm_test_check_max_tmds_rate_bpc_fallback_yuv420(struct kunit *test)
  *   RGB/10bpc
  * - The chosen mode has a TMDS character rate lower than the display
  *   supports in YUV422/12bpc.
+ * - The HDMI connector state's color format property is unset (i.e. AUTO)
  *
  * Then we will prefer to keep the RGB format with a lower bpc over
  * picking YUV422.
@@ -1609,6 +1627,7 @@ static void drm_test_check_max_tmds_rate_bpc_fallback_ignore_yuv422(struct kunit
 
 	conn_state = conn->state;
 	KUNIT_ASSERT_NOT_NULL(test, conn_state);
+	KUNIT_ASSERT_EQ(test, conn_state->color_format, DRM_CONNECTOR_COLOR_FORMAT_AUTO);
 
 	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_bpc, 10);
 	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, DRM_OUTPUT_COLOR_FORMAT_RGB444);
@@ -1626,6 +1645,7 @@ static void drm_test_check_max_tmds_rate_bpc_fallback_ignore_yuv422(struct kunit
  *   RGB/8bpc
  * - The chosen mode has a TMDS character rate lower than the display
  *   supports in YUV420/12bpc.
+ * - The HDMI connector state's color format property is unset (i.e. AUTO)
  *
  * Then we will prefer to keep the RGB format with a lower bpc over
  * picking YUV420.
@@ -1687,6 +1707,7 @@ static void drm_test_check_max_tmds_rate_bpc_fallback_ignore_yuv420(struct kunit
 
 	conn_state = conn->state;
 	KUNIT_ASSERT_NOT_NULL(test, conn_state);
+	KUNIT_ASSERT_EQ(test, conn_state->color_format, DRM_CONNECTOR_COLOR_FORMAT_AUTO);
 
 	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_bpc, 8);
 	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, DRM_OUTPUT_COLOR_FORMAT_RGB444);
@@ -2198,6 +2219,217 @@ static void drm_test_check_disable_connector(struct kunit *test)
 	drm_modeset_acquire_fini(&ctx);
 }
 
+struct color_format_test_param {
+	enum drm_connector_color_format fmt;
+	enum drm_output_color_format expected;
+	int expected_ret;
+	const char *desc;
+};
+
+/* Test that if:
+ * - an HDMI connector supports RGB, YUV444, YUV422, and YUV420
+ * - the display supports RGB, YUV444, YUV422, and YUV420
+ * - the "color format" property is set
+ * then, for the preferred mode, for a given "color format" option:
+ * - DRM_CONNECTOR_COLOR_FORMAT_AUTO results in an output format of RGB
+ * - DRM_CONNECTOR_COLOR_FORMAT_YCBCR422 results in an output format of YUV422
+ * - DRM_CONNECTOR_COLOR_FORMAT_YCBCR420 results in an output format of YUV420
+ * - DRM_CONNECTOR_COLOR_FORMAT_YCBCR444 results in an output format of YUV444
+ * - DRM_CONNECTOR_COLOR_FORMAT_RGB results in an HDMI output format of RGB
+ */
+static void drm_test_check_hdmi_color_format(struct kunit *test)
+{
+	const struct color_format_test_param *param = test->param_value;
+	struct drm_atomic_helper_connector_hdmi_priv *priv;
+	struct drm_connector_state *conn_state;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_crtc_state *crtc_state;
+	struct drm_atomic_state *state;
+	struct drm_display_info *info;
+	struct drm_display_mode *preferred;
+	int ret;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+				BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422) |
+				BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420) |
+				BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444),
+				12,
+				&dummy_connector_hdmi_funcs,
+				test_edid_hdmi_4k_rgb_yuv420_dc_max_340mhz);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	KUNIT_ASSERT_TRUE(test, priv->connector.ycbcr_420_allowed);
+
+	info = &priv->connector.display_info;
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, info);
+	preferred = find_preferred_mode(&priv->connector);
+	KUNIT_ASSERT_TRUE(test, drm_mode_is_420(info, preferred));
+
+	state = drm_kunit_helper_atomic_state_alloc(test, &priv->drm, &ctx);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+	conn_state = drm_atomic_get_connector_state(state, &priv->connector);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	conn_state->color_format = param->fmt;
+
+	ret = drm_atomic_set_crtc_for_connector(conn_state, priv->crtc);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state = drm_atomic_get_crtc_state(state, priv->crtc);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
+
+	ret = drm_atomic_set_mode_for_crtc(crtc_state, preferred);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state->enable = true;
+	crtc_state->active = true;
+
+	ret = drm_atomic_check_only(state);
+	KUNIT_EXPECT_EQ(test, ret, param->expected_ret);
+	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, param->expected);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
+static const struct color_format_test_param hdmi_color_format_params[] = {
+	{
+		.fmt = DRM_CONNECTOR_COLOR_FORMAT_AUTO,
+		.expected = DRM_OUTPUT_COLOR_FORMAT_RGB444,
+		.expected_ret = 0,
+		.desc = "AUTO -> RGB"
+	},
+	{
+		.fmt = DRM_CONNECTOR_COLOR_FORMAT_YCBCR422,
+		.expected = DRM_OUTPUT_COLOR_FORMAT_YCBCR422,
+		.expected_ret = 0,
+		.desc = "YCBCR422 -> YUV422"
+	},
+	{
+		.fmt = DRM_CONNECTOR_COLOR_FORMAT_YCBCR420,
+		.expected = DRM_OUTPUT_COLOR_FORMAT_YCBCR420,
+		.expected_ret = 0,
+		.desc = "YCBCR420 -> YUV420"
+	},
+	{
+		.fmt = DRM_CONNECTOR_COLOR_FORMAT_YCBCR444,
+		.expected = DRM_OUTPUT_COLOR_FORMAT_YCBCR444,
+		.expected_ret = 0,
+		.desc = "YCBCR444 -> YUV444"
+	},
+	{
+		.fmt = DRM_CONNECTOR_COLOR_FORMAT_RGB444,
+		.expected = DRM_OUTPUT_COLOR_FORMAT_RGB444,
+		.expected_ret = 0,
+		.desc = "RGB -> RGB"
+	},
+};
+
+KUNIT_ARRAY_PARAM_DESC(check_hdmi_color_format, hdmi_color_format_params, desc);
+
+/* Test that if:
+ * - the HDMI connector supports RGB, YUV422, YUV420, and YUV444
+ * - the display has a YUV420-only mode
+ * - the "color format" property is explicitly set (i.e. !AUTO)
+ * then:
+ * - color format DRM_CONNECTOR_COLOR_FORMAT_RGB444 will fail
+ *   drm_atomic_check_only for the YUV420-only mode with -EINVAL
+ * - color format DRM_CONNECTOR_COLOR_FORMAT_YCBCR444 will fail
+ *   drm_atomic_check_only for the YUV420-only mode with -EINVAL
+ * - color format DRM_CONNECTOR_COLOR_FORMAT_YCBCR422 will fail
+ *   drm_atomic_check_only for the YUV420-only mode with -EINVAL
+ * - color format DRM_CONNECTOR_COLOR_FORMAT_YCBCR420 passes
+ *   drm_atomic_check_only for the YUV420-only mode
+ */
+static void drm_test_check_hdmi_color_format_420_only(struct kunit *test)
+{
+	const struct color_format_test_param *param = test->param_value;
+	struct drm_atomic_helper_connector_hdmi_priv *priv;
+	struct drm_connector_state *conn_state;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_crtc_state *crtc_state;
+	struct drm_atomic_state *state;
+	struct drm_display_mode *dank;
+	int ret;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+				BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422) |
+				BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420) |
+				BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444),
+				12,
+				&dummy_connector_hdmi_funcs,
+				test_edid_hdmi_1080p_rgb_yuv_4k_yuv420_dc_max_200mhz);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	dank = find_420_only_mode(&priv->connector);
+	KUNIT_ASSERT_NOT_NULL(test, dank);
+
+	state = drm_kunit_helper_atomic_state_alloc(test, &priv->drm, &ctx);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
+
+	conn_state = drm_atomic_get_connector_state(state, &priv->connector);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	conn_state->color_format = param->fmt;
+
+	ret = drm_atomic_set_crtc_for_connector(conn_state, priv->crtc);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state = drm_atomic_get_crtc_state(state, priv->crtc);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
+
+	ret = drm_atomic_set_mode_for_crtc(crtc_state, dank);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	crtc_state->enable = true;
+	crtc_state->active = true;
+
+	ret = drm_atomic_check_only(state);
+	KUNIT_EXPECT_EQ(test, ret, param->expected_ret);
+	if (!param->expected_ret)
+		KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, param->expected);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+};
+
+static const struct color_format_test_param hdmi_color_format_420_only_params[] = {
+	{
+		.fmt = DRM_CONNECTOR_COLOR_FORMAT_RGB444,
+		.expected = DRM_OUTPUT_COLOR_FORMAT_RGB444,
+		.expected_ret = -EINVAL,
+		.desc = "RGB should fail"
+	},
+	{
+		.fmt = DRM_CONNECTOR_COLOR_FORMAT_YCBCR444,
+		.expected = DRM_OUTPUT_COLOR_FORMAT_YCBCR444,
+		.expected_ret = -EINVAL,
+		.desc = "YUV444 should fail"
+	},
+	{
+		.fmt = DRM_CONNECTOR_COLOR_FORMAT_YCBCR422,
+		.expected = DRM_OUTPUT_COLOR_FORMAT_YCBCR422,
+		.expected_ret = -EINVAL,
+		.desc = "YUV422 should fail"
+	},
+	{
+		.fmt = DRM_CONNECTOR_COLOR_FORMAT_YCBCR420,
+		.expected = DRM_OUTPUT_COLOR_FORMAT_YCBCR420,
+		.expected_ret = 0,
+		.desc = "YUV420 should work"
+	},
+};
+
+KUNIT_ARRAY_PARAM_DESC(check_hdmi_color_format_420_only,
+		       hdmi_color_format_420_only_params, desc);
+
 static struct kunit_case drm_atomic_helper_connector_hdmi_check_tests[] = {
 	KUNIT_CASE(drm_test_check_broadcast_rgb_auto_cea_mode),
 	KUNIT_CASE(drm_test_check_broadcast_rgb_auto_cea_mode_vic_1),
@@ -2227,6 +2459,10 @@ static struct kunit_case drm_atomic_helper_connector_hdmi_check_tests[] = {
 	KUNIT_CASE(drm_test_check_tmds_char_rate_rgb_8bpc),
 	KUNIT_CASE(drm_test_check_tmds_char_rate_rgb_10bpc),
 	KUNIT_CASE(drm_test_check_tmds_char_rate_rgb_12bpc),
+	KUNIT_CASE_PARAM(drm_test_check_hdmi_color_format,
+			 check_hdmi_color_format_gen_params),
+	KUNIT_CASE_PARAM(drm_test_check_hdmi_color_format_420_only,
+			 check_hdmi_color_format_420_only_gen_params),
 	/*
 	 * TODO: We should have tests to check that a change in the
 	 * format triggers a CRTC mode change just like we do for the

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 03/25] drm: Add new general DRM property "color format"
From: Nicolas Frattaroli @ 2026-04-09 15:44 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli, Werner Sembach, Andri Yngvason, Marius Vlad
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

Add a new general DRM property named "color format" which can be used by
userspace to request the display driver to output a particular color
format.

Possible string values for the new enum property are:
 - "AUTO" (setup by default, driver internally picks the color format)
 - "RGB"
 - "YUV 4:4:4"
 - "YUV 4:2:2"
 - "YUV 4:2:0"

Drivers should advertise from this list the formats they support in an
optimistic best-case scenario. EDID data from the sink can then be used
in the kernel's atomic check phase to restrict this set of formats, as
well as by userspace to make a correct choice in the first place.

Co-developed-by: Werner Sembach <wse@tuxedocomputers.com>
Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
Co-developed-by: Andri Yngvason <andri@yngvason.is>
Signed-off-by: Andri Yngvason <andri@yngvason.is>
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 Documentation/gpu/drm-kms.rst       |   6 ++
 drivers/gpu/drm/drm_atomic_helper.c |   5 ++
 drivers/gpu/drm/drm_atomic_uapi.c   |  11 +++
 drivers/gpu/drm/drm_connector.c     | 155 ++++++++++++++++++++++++++++++++++++
 include/drm/drm_connector.h         | 108 +++++++++++++++++++++++++
 5 files changed, 285 insertions(+)

diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst
index 2292e65f044c..da5133b672d3 100644
--- a/Documentation/gpu/drm-kms.rst
+++ b/Documentation/gpu/drm-kms.rst
@@ -599,6 +599,12 @@ Color Management Properties
 .. kernel-doc:: drivers/gpu/drm/drm_color_mgmt.c
    :doc: overview
 
+Color Format Property
+---------------------
+
+.. kernel-doc:: drivers/gpu/drm/drm_connector.c
+   :doc: Color format
+
 Tile Group Property
 -------------------
 
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 2e7e8ed8ad7f..0de9748a82c6 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -737,6 +737,11 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
 			if (old_connector_state->max_requested_bpc !=
 			    new_connector_state->max_requested_bpc)
 				new_crtc_state->connectors_changed = true;
+
+			if (old_connector_state->color_format !=
+			    new_connector_state->color_format)
+				new_crtc_state->connectors_changed = true;
+
 		}
 
 		if (funcs->atomic_check)
diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index 5bd5bf6661df..dee510c85e59 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -935,6 +935,15 @@ static int drm_atomic_connector_set_property(struct drm_connector *connector,
 		state->privacy_screen_sw_state = val;
 	} else if (property == connector->broadcast_rgb_property) {
 		state->hdmi.broadcast_rgb = val;
+	} else if (property == connector->color_format_property) {
+		if (val > INT_MAX || !drm_connector_color_format_valid(val)) {
+			drm_dbg_atomic(connector->dev,
+				       "[CONNECTOR:%d:%s] unknown color format %llu\n",
+				       connector->base.id, connector->name, val);
+			return -EINVAL;
+		}
+
+		state->color_format = val;
 	} else if (connector->funcs->atomic_set_property) {
 		return connector->funcs->atomic_set_property(connector,
 				state, property, val);
@@ -1020,6 +1029,8 @@ drm_atomic_connector_get_property(struct drm_connector *connector,
 		*val = state->privacy_screen_sw_state;
 	} else if (property == connector->broadcast_rgb_property) {
 		*val = state->hdmi.broadcast_rgb;
+	} else if (property == connector->color_format_property) {
+		*val = state->color_format;
 	} else if (connector->funcs->atomic_get_property) {
 		return connector->funcs->atomic_get_property(connector,
 				state, property, val);
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 47dc53c4a738..1c4f3ff7d84f 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1388,6 +1388,18 @@ static const u32 hdmi_colorspaces =
 	BIT(DRM_MODE_COLORIMETRY_DCI_P3_RGB_D65) |
 	BIT(DRM_MODE_COLORIMETRY_DCI_P3_RGB_THEATER);
 
+static const u32 hdmi_colorformats =
+	BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420);
+
+static const u32 dp_colorformats =
+	BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420);
+
 /*
  * As per DP 1.4a spec, 2.2.5.7.5 VSC SDP Payload for Pixel Encoding/Colorimetry
  * Format Table 2-120
@@ -2940,6 +2952,149 @@ int drm_connector_attach_colorspace_property(struct drm_connector *connector)
 }
 EXPORT_SYMBOL(drm_connector_attach_colorspace_property);
 
+/**
+ * DOC: Color format
+ *
+ * The connector "color format" property allows userspace to request a specific
+ * color model on the output of the connector. Not all values listed by the
+ * property are guaranteed to work for every sink; rather, it is an optimistic
+ * listing of color formats that the source could output depending on
+ * circumstances.
+ *
+ * Whether it actually can output a certain color format is determined during
+ * the atomic check phase. Consequently, a userspace application that sets the
+ * color format to a value other than "AUTO" should check whether its atomic
+ * commit succeeded.
+ *
+ * Possible values for "color format":
+ *
+ * "AUTO":
+ *	The driver or display protocol helpers should pick a suitable color
+ *	format. All implementations of a specific display protocol will behave
+ *	the same way with "AUTO", but different display protocols do not
+ *	necessarily have the same "AUTO" semantics.
+ *
+ *	For HDMI connectors, "AUTO" picks RGB, but falls back to YUV 4:2:0 if
+ *	the bandwidth required for full-scale RGB is not available, or the mode
+ *	is YUV 4:2:0-only, as long as the mode, source, and sink all support
+ *	YUV 4:2:0.
+ * "RGB":
+ *	RGB output format. The quantization range (limited/full) depends on the
+ *	value of the "Broadcast RGB" property if it is present on the connector.
+ * "YUV 4:4:4":
+ *	YUV 4:4:4 (a.k.a. YCbCr 4:4:4) output format. Chroma is not subsampled.
+ *	The quantization range defaults to limited.
+ * "YUV 4:2:2":
+ *	YUV 4:2:2 (a.k.a. YCbCr 4:2:2) output format. Chroma has half the
+ *	horizontal resolution of Luma. The quantization range defaults to
+ *	limited.
+ * "YUV 4:2:0":
+ *	YUV 4:2:0 (a.k.a. YCbCr 4:2:0) output format. Chroma has half the
+ *	horizontal and vertical resolution of Luma. The quantization range
+ *	defaults to limited.
+ *
+ * A sink may only support some color formats in specific modes and at specific
+ * bit depths. The atomic modesetting API should be used to set a working
+ * configuration in one go, as an unsupported combination of parameters is
+ * rejected.
+ */
+
+/**
+ * drm_connector_attach_color_format_property - create and attach color format property
+ * @connector: connector to create the color format property on
+ * @supported_color_formats: bitmask of bit-shifted &enum drm_output_color_format
+ *                           values the connector supports
+ *
+ * Called by a driver to create a color format property. The property is
+ * attached to the connector automatically on success.
+ *
+ * @supported_color_formats should only include color formats the connector
+ * type can actually support.
+ *
+ * Returns:
+ * 0 on success, negative errno on error
+ */
+int drm_connector_attach_color_format_property(struct drm_connector *connector,
+					       unsigned long supported_color_formats)
+{
+	struct drm_device *dev = connector->dev;
+	struct drm_prop_enum_list enum_list[DRM_CONNECTOR_COLOR_FORMAT_COUNT];
+	unsigned int i = 0;
+	unsigned long fmt;
+
+	if (connector->color_format_property)
+		return 0;
+
+	if (!supported_color_formats) {
+		drm_err(dev, "No supported color formats provided on [CONNECTOR:%d:%s]\n",
+			connector->base.id, connector->name);
+		return -EINVAL;
+	}
+
+	if (supported_color_formats & ~GENMASK(DRM_OUTPUT_COLOR_FORMAT_COUNT - 1, 0)) {
+		drm_err(dev, "Unknown color formats provided on [CONNECTOR:%d:%s]\n",
+			connector->base.id, connector->name);
+		return -EINVAL;
+	}
+
+	switch (connector->connector_type) {
+	case DRM_MODE_CONNECTOR_HDMIA:
+	case DRM_MODE_CONNECTOR_HDMIB:
+		if (supported_color_formats & ~hdmi_colorformats) {
+			drm_err(dev, "Color formats not allowed for HDMI on [CONNECTOR:%d:%s]\n",
+				connector->base.id, connector->name);
+			return -EINVAL;
+		}
+		break;
+	case DRM_MODE_CONNECTOR_DisplayPort:
+	case DRM_MODE_CONNECTOR_eDP:
+		if (supported_color_formats & ~dp_colorformats) {
+			drm_err(dev, "Color formats not allowed for DP on [CONNECTOR:%d:%s]\n",
+				connector->base.id, connector->name);
+			return -EINVAL;
+		}
+		break;
+	}
+
+	enum_list[0].name = "AUTO";
+	enum_list[0].type = DRM_CONNECTOR_COLOR_FORMAT_AUTO;
+
+	for_each_set_bit(fmt, &supported_color_formats, DRM_OUTPUT_COLOR_FORMAT_COUNT) {
+		switch (fmt) {
+		case DRM_OUTPUT_COLOR_FORMAT_RGB444:
+			enum_list[++i].type = DRM_CONNECTOR_COLOR_FORMAT_RGB444;
+			break;
+		case DRM_OUTPUT_COLOR_FORMAT_YCBCR444:
+			enum_list[++i].type = DRM_CONNECTOR_COLOR_FORMAT_YCBCR444;
+			break;
+		case DRM_OUTPUT_COLOR_FORMAT_YCBCR422:
+			enum_list[++i].type = DRM_CONNECTOR_COLOR_FORMAT_YCBCR422;
+			break;
+		case DRM_OUTPUT_COLOR_FORMAT_YCBCR420:
+			enum_list[++i].type = DRM_CONNECTOR_COLOR_FORMAT_YCBCR420;
+			break;
+		default:
+			drm_warn(dev, "Unknown supported format %ld on [CONNECTOR:%d:%s]\n",
+				 fmt, connector->base.id, connector->name);
+			continue;
+		}
+		enum_list[i].name = drm_hdmi_connector_get_output_format_name(fmt);
+	}
+
+	connector->color_format_property =
+		drm_property_create_enum(dev, DRM_MODE_PROP_ENUM, "color format",
+					 enum_list, i + 1);
+
+	if (!connector->color_format_property)
+		return -ENOMEM;
+
+	drm_object_attach_property(&connector->base, connector->color_format_property,
+				   DRM_CONNECTOR_COLOR_FORMAT_AUTO);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_connector_attach_color_format_property);
+
 /**
  * drm_connector_atomic_hdr_metadata_equal - checks if the hdr metadata changed
  * @old_state: old connector state to compare
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index f83f28cae207..620f700fbe76 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -571,14 +571,106 @@ enum drm_colorspace {
  *   YCbCr 4:2:2 output format (ie. with horizontal subsampling)
  * @DRM_OUTPUT_COLOR_FORMAT_YCBCR420:
  *   YCbCr 4:2:0 output format (ie. with horizontal and vertical subsampling)
+ * @DRM_OUTPUT_COLOR_FORMAT_COUNT:
+ *   Number of valid output color format values in this enum
  */
 enum drm_output_color_format {
 	DRM_OUTPUT_COLOR_FORMAT_RGB444 = 0,
 	DRM_OUTPUT_COLOR_FORMAT_YCBCR444,
 	DRM_OUTPUT_COLOR_FORMAT_YCBCR422,
 	DRM_OUTPUT_COLOR_FORMAT_YCBCR420,
+	DRM_OUTPUT_COLOR_FORMAT_COUNT,
 };
 
+/**
+ * enum drm_connector_color_format - Connector Color Format Request
+ *
+ * This enum, unlike &enum drm_output_color_format, is used to specify requests
+ * for a specific color format on a connector through the DRM "color format"
+ * property. The difference is that it has an "AUTO" value to specify that
+ * no specific choice has been made.
+ */
+enum drm_connector_color_format {
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_AUTO: The driver or display protocol
+	 * helpers should pick a suitable color format. All implementations of a
+	 * specific display protocol must behave the same way with "AUTO", but
+	 * different display protocols do not necessarily have the same "AUTO"
+	 * semantics.
+	 *
+	 * For HDMI, "AUTO" picks RGB, but falls back to YCbCr 4:2:0 if the
+	 * bandwidth required for full-scale RGB is not available, or the mode
+	 * is YCbCr 4:2:0-only, as long as the mode and output both support
+	 * YCbCr 4:2:0.
+	 *
+	 * For display protocols other than HDMI, the recursive bridge chain
+	 * format selection picks the first chain of bridge formats that works,
+	 * as has already been the case before the introduction of the "color
+	 * format" property. Non-HDMI bridges should therefore either sort their
+	 * bus output formats by preference, or agree on a unified auto format
+	 * selection logic that's implemented in a common state helper (like
+	 * how HDMI does it).
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_AUTO = 0,
+
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_RGB444: RGB output format. The
+	 * quantization range depends on the value of the "Broadcast RGB"
+	 * property if it is present on the connector.
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_RGB444,
+
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_YCBCR444: YCbCr 4:4:4 output format (ie.
+	 * not subsampled). Quantization range is "Limited" by default.
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_YCBCR444,
+
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_YCBCR422: YCbCr 4:2:2 output format (ie.
+	 * with horizontal subsampling). Quantization range is "Limited" by
+	 * default.
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_YCBCR422,
+
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_YCBCR420: YCbCr 4:2:0 output format (ie.
+	 * with horizontal and vertical subsampling). Quantization range is
+	 * "Limited" by default.
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_YCBCR420,
+
+	/**
+	 * @DRM_CONNECTOR_COLOR_FORMAT_COUNT: Number of valid connector color
+	 * format values in this enum
+	 */
+	DRM_CONNECTOR_COLOR_FORMAT_COUNT,
+};
+
+/**
+ * drm_connector_color_format_valid - Validate drm_connector_color_format value
+ * @fmt: value to check against all values of &enum drm_connector_color_format
+ *
+ * Checks whether the passed in value of @fmt is one of the allowable values in
+ * &enum drm_connector_color_format.
+ *
+ * Returns: %true if it's a valid value for the enum, %false otherwise.
+ */
+static inline bool __pure
+drm_connector_color_format_valid(enum drm_connector_color_format fmt)
+{
+	switch (fmt) {
+	case DRM_CONNECTOR_COLOR_FORMAT_AUTO:
+	case DRM_CONNECTOR_COLOR_FORMAT_RGB444:
+	case DRM_CONNECTOR_COLOR_FORMAT_YCBCR444:
+	case DRM_CONNECTOR_COLOR_FORMAT_YCBCR422:
+	case DRM_CONNECTOR_COLOR_FORMAT_YCBCR420:
+		return true;
+	default:
+		return false;
+	}
+}
+
 const char *
 drm_hdmi_connector_get_output_format_name(enum drm_output_color_format fmt);
 
@@ -1167,6 +1259,13 @@ struct drm_connector_state {
 	 */
 	enum drm_colorspace colorspace;
 
+	/**
+	 * @color_format: State variable for Connector property to request
+	 * color format change on Sink. This is most commonly used to switch
+	 * between RGB to YUV and vice-versa.
+	 */
+	enum drm_connector_color_format color_format;
+
 	/**
 	 * @writeback_job: Writeback job for writeback connectors
 	 *
@@ -2165,6 +2264,12 @@ struct drm_connector {
 	 */
 	struct drm_property *colorspace_property;
 
+	/**
+	 * @color_format_property: Connector property to set the suitable
+	 * color format supported by the sink.
+	 */
+	struct drm_property *color_format_property;
+
 	/**
 	 * @path_blob_ptr:
 	 *
@@ -2648,6 +2753,9 @@ bool drm_connector_has_possible_encoder(struct drm_connector *connector,
 					struct drm_encoder *encoder);
 const char *drm_get_colorspace_name(enum drm_colorspace colorspace);
 
+int drm_connector_attach_color_format_property(struct drm_connector *connector,
+					       unsigned long supported_color_formats);
+
 /**
  * drm_for_each_connector_iter - connector_list iterator macro
  * @connector: &struct drm_connector pointer used as cursor

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 19/25] drm/connector: Register color format property on HDMI connectors
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

The drmm_connector_hdmi_init function can figure out what DRM color
formats are supported by a particular connector based on the supported
HDMI format bitmask that's passed in.

Use it to register the drm color format property.

Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/drm_connector.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 1c4f3ff7d84f..0da136a93dd6 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -627,6 +627,10 @@ int drmm_connector_hdmi_init(struct drm_device *dev,
 	if (max_bpc > 8)
 		drm_connector_attach_hdr_output_metadata_property(connector);
 
+	ret = drm_connector_attach_color_format_property(connector, supported_formats);
+	if (ret)
+		return ret;
+
 	connector->hdmi.funcs = hdmi_funcs;
 
 	return 0;

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 17/25] drm/rockchip: dw_hdmi_qp: Implement "color format" DRM property
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli, Cristian Ciocaltea
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

Switch between requested color formats by setting the right bus formats,
configuring the VO GRF registers, and setting the right output mode.

To do this, the encoder's atomic_check queries the bus format of the
first bridge, which was determined by the bridge chain recursive format
selection. Pick the input format if it's !FIXED, otherwise, pick the
output format.

The previously unused GRF register color format defines are redone as
well. Both RK3588 and RK3576 use the same defines; it didn't look like
this as there was a typo in the previously (unused) definition.

Reviewed-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 107 ++++++++++++++++++++++---
 1 file changed, 98 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
index c78db7f8ab6c..9bf727c1dd7d 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
@@ -11,6 +11,7 @@
 #include <linux/gpio/consumer.h>
 #include <linux/hw_bitfield.h>
 #include <linux/mfd/syscon.h>
+#include <linux/media-bus-format.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/phy/phy.h>
@@ -44,10 +45,6 @@
 #define RK3576_8BPC			0x0
 #define RK3576_10BPC			0x6
 #define RK3576_COLOR_FORMAT_MASK	GENMASK(7, 4)
-#define RK3576_RGB			0x9
-#define RK3576_YUV422			0x1
-#define RK3576_YUV444			0x2
-#define RK3576_YUV420			0x3
 #define RK3576_CECIN_MASK		BIT(3)
 
 #define RK3576_VO0_GRF_SOC_CON14	0x0038
@@ -75,8 +72,6 @@
 #define RK3588_8BPC			0x0
 #define RK3588_10BPC			0x6
 #define RK3588_COLOR_FORMAT_MASK	GENMASK(3, 0)
-#define RK3588_RGB			0x0
-#define RK3588_YUV420			0x3
 #define RK3588_SCLIN_MASK		BIT(9)
 #define RK3588_SDAIN_MASK		BIT(10)
 #define RK3588_MODE_MASK		BIT(11)
@@ -88,6 +83,11 @@
 #define HOTPLUG_DEBOUNCE_MS		150
 #define MAX_HDMI_PORT_NUM		2
 
+#define RK_COLOR_FMT_RGB		0x0
+#define RK_COLOR_FMT_YUV422		0x1
+#define RK_COLOR_FMT_YUV444		0x2
+#define RK_COLOR_FMT_YUV420		0x3
+
 struct rockchip_hdmi_qp {
 	struct device *dev;
 	struct regmap *regmap;
@@ -116,6 +116,33 @@ static struct rockchip_hdmi_qp *to_rockchip_hdmi_qp(struct drm_encoder *encoder)
 	return container_of(rkencoder, struct rockchip_hdmi_qp, encoder);
 }
 
+/**
+ * dw_hdmi_qp_rockchip_bus_fmt_to_reg - converts a bus format to a GRF reg value
+ * @bus_fmt: One of the MEDIA_BUS_FMT_s allowed by this driver's atomic_check
+ *
+ * Returns: an unshifted value to be written to the COLOR_FORMAT GRF register
+ * on success, or %-EINVAL if the bus format is not supported.
+ */
+static int __pure dw_hdmi_qp_rockchip_bus_fmt_to_reg(u32 bus_fmt)
+{
+	switch (bus_fmt) {
+	case MEDIA_BUS_FMT_RGB888_1X24:
+	case MEDIA_BUS_FMT_RGB101010_1X30:
+		return RK_COLOR_FMT_RGB;
+	case MEDIA_BUS_FMT_UYVY8_1X16:
+	case MEDIA_BUS_FMT_UYVY10_1X20:
+		return RK_COLOR_FMT_YUV422;
+	case MEDIA_BUS_FMT_YUV8_1X24:
+	case MEDIA_BUS_FMT_YUV10_1X30:
+		return RK_COLOR_FMT_YUV444;
+	case MEDIA_BUS_FMT_UYYVYY8_0_5X24:
+	case MEDIA_BUS_FMT_UYYVYY10_0_5X30:
+		return RK_COLOR_FMT_YUV420;
+	}
+
+	return -EINVAL;
+}
+
 static void dw_hdmi_qp_rockchip_encoder_enable(struct drm_encoder *encoder)
 {
 	struct rockchip_hdmi_qp *hdmi = to_rockchip_hdmi_qp(encoder);
@@ -131,29 +158,83 @@ static void dw_hdmi_qp_rockchip_encoder_enable(struct drm_encoder *encoder)
 		hdmi->ctrl_ops->enc_init(hdmi, to_rockchip_crtc_state(crtc->state));
 }
 
+/**
+ * dw_hdmi_qp_rockchip_get_vop_format - get the bus format VOP should output
+ * @encoder: pointer to a &struct drm_encoder
+ * @conn_state: pointer to the current atomic &struct drm_connector_state
+ *
+ * Determines which bus format the Rockchip video processor should output as
+ * to feed into the bridge chain.
+ *
+ * Returns a MEDIA_BUS_FMT_* on success, or %0 on error.
+ */
+static u32 dw_hdmi_qp_rockchip_get_vop_format(struct drm_encoder *encoder,
+					      struct drm_connector_state *conn_state)
+{
+	struct drm_bridge *bridge __free(drm_bridge_put) = NULL;
+	struct drm_bridge_state *bstate;
+
+	bridge = drm_bridge_chain_get_first_bridge(encoder);
+	if (!bridge)
+		return 0;
+
+	bstate = drm_atomic_get_bridge_state(conn_state->state, bridge);
+	if (!bstate)
+		return 0;
+
+	if (bstate->input_bus_cfg.format != MEDIA_BUS_FMT_FIXED)
+		return bstate->input_bus_cfg.format;
+
+	return bstate->output_bus_cfg.format;
+}
+
 static int
 dw_hdmi_qp_rockchip_encoder_atomic_check(struct drm_encoder *encoder,
 					 struct drm_crtc_state *crtc_state,
 					 struct drm_connector_state *conn_state)
 {
-	struct rockchip_hdmi_qp *hdmi = to_rockchip_hdmi_qp(encoder);
 	struct rockchip_crtc_state *s = to_rockchip_crtc_state(crtc_state);
+	struct rockchip_hdmi_qp *hdmi = to_rockchip_hdmi_qp(encoder);
 	union phy_configure_opts phy_cfg = {};
+	u32 ingest_fmt;
 	int ret;
 
+	ingest_fmt = dw_hdmi_qp_rockchip_get_vop_format(encoder, conn_state);
+	if (!ingest_fmt)
+		return -EINVAL;
+
 	if (hdmi->tmds_char_rate == conn_state->hdmi.tmds_char_rate &&
-	    s->output_bpc == conn_state->hdmi.output_bpc)
+	    s->output_bpc == conn_state->hdmi.output_bpc &&
+	    s->bus_format == ingest_fmt)
 		return 0;
 
+	switch (ingest_fmt) {
+	case MEDIA_BUS_FMT_RGB888_1X24:
+	case MEDIA_BUS_FMT_RGB101010_1X30:
+	case MEDIA_BUS_FMT_YUV8_1X24:
+	case MEDIA_BUS_FMT_YUV10_1X30:
+		s->output_mode = ROCKCHIP_OUT_MODE_AAAA;
+		break;
+	case MEDIA_BUS_FMT_UYVY8_1X16:
+		s->output_mode = ROCKCHIP_OUT_MODE_YUV422;
+		break;
+	case MEDIA_BUS_FMT_UYYVYY8_0_5X24:
+	case MEDIA_BUS_FMT_UYYVYY10_0_5X30:
+		s->output_mode = ROCKCHIP_OUT_MODE_YUV420;
+		break;
+	default:
+		return -EINVAL;
+	}
+
 	phy_cfg.hdmi.tmds_char_rate = conn_state->hdmi.tmds_char_rate;
 	phy_cfg.hdmi.bpc = conn_state->hdmi.output_bpc;
 
 	ret = phy_configure(hdmi->phy, &phy_cfg);
 	if (!ret) {
 		hdmi->tmds_char_rate = conn_state->hdmi.tmds_char_rate;
-		s->output_mode = ROCKCHIP_OUT_MODE_AAAA;
 		s->output_type = DRM_MODE_CONNECTOR_HDMIA;
 		s->output_bpc = conn_state->hdmi.output_bpc;
+		s->bus_format = ingest_fmt;
 	} else {
 		dev_err(hdmi->dev, "Failed to configure phy: %d\n", ret);
 	}
@@ -383,6 +464,7 @@ static void dw_hdmi_qp_rk3588_io_init(struct rockchip_hdmi_qp *hdmi)
 static void dw_hdmi_qp_rk3576_enc_init(struct rockchip_hdmi_qp *hdmi,
 				       struct rockchip_crtc_state *state)
 {
+	int color = dw_hdmi_qp_rockchip_bus_fmt_to_reg(state->bus_format);
 	u32 val;
 
 	if (state->output_bpc == 10)
@@ -390,12 +472,16 @@ static void dw_hdmi_qp_rk3576_enc_init(struct rockchip_hdmi_qp *hdmi,
 	else
 		val = FIELD_PREP_WM16(RK3576_COLOR_DEPTH_MASK, RK3576_8BPC);
 
+	if (likely(color >= 0))
+		val |= FIELD_PREP_WM16(RK3576_COLOR_FORMAT_MASK, color);
+
 	regmap_write(hdmi->vo_regmap, RK3576_VO0_GRF_SOC_CON8, val);
 }
 
 static void dw_hdmi_qp_rk3588_enc_init(struct rockchip_hdmi_qp *hdmi,
 				       struct rockchip_crtc_state *state)
 {
+	int color = dw_hdmi_qp_rockchip_bus_fmt_to_reg(state->bus_format);
 	u32 val;
 
 	if (state->output_bpc == 10)
@@ -403,6 +489,9 @@ static void dw_hdmi_qp_rk3588_enc_init(struct rockchip_hdmi_qp *hdmi,
 	else
 		val = FIELD_PREP_WM16(RK3588_COLOR_DEPTH_MASK, RK3588_8BPC);
 
+	if (likely(color >= 0))
+		val |= FIELD_PREP_WM16(RK3588_COLOR_FORMAT_MASK, color);
+
 	regmap_write(hdmi->vo_regmap,
 		     hdmi->port_id ? RK3588_GRF_VO1_CON6 : RK3588_GRF_VO1_CON3,
 		     val);

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 18/25] drm/rockchip: dw_hdmi_qp: Set supported_formats platdata
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli, Cristian Ciocaltea
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

With the introduction of the supported_formats member in the
dw-hdmi-qp platform data struct, drivers that have access to this
information should now set it.

Set it in the rockchip dw_hdmi_qp glue driver.

This allows this information to be passed down to the dw-hdmi-qp core,
which sets it in the bridge it creates, and consequently will allow the
common HDMI bridge code to act on it.

Reviewed-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
index 9bf727c1dd7d..a7a8bdb76ce6 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
@@ -602,6 +602,10 @@ static int dw_hdmi_qp_rockchip_bind(struct device *dev, struct device *master,
 	plat_data.phy_data = hdmi;
 	plat_data.max_bpc = 10;
 
+	plat_data.supported_formats = BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+				      BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444) |
+				      BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422);
+
 	encoder = &hdmi->encoder.encoder;
 	encoder->possible_crtcs = drm_of_find_possible_crtcs(drm, dev->of_node);
 

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 16/25] drm/bridge: dw-hdmi-qp: Use common HDMI output bus fmts helper
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli, Cristian Ciocaltea
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

Make use of the common drm_bridge_funcs.atomic_get_output_bus_fmts
helper for HDMI bridge connectors.

This allows dw-hdmi-qp HDMI bridges to participate in recursive bus
format selection in a meaningful way.

Reviewed-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
index d649a1cf07f5..5380aa7d82a8 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-qp.c
@@ -1192,6 +1192,7 @@ static int dw_hdmi_qp_cec_transmit(struct drm_bridge *bridge, u8 attempts,
 #endif /* CONFIG_DRM_DW_HDMI_QP_CEC */
 
 static const struct drm_bridge_funcs dw_hdmi_qp_bridge_funcs = {
+	.atomic_get_output_bus_fmts = drm_atomic_helper_bridge_get_hdmi_output_bus_fmts,
 	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
 	.atomic_reset = drm_atomic_helper_bridge_reset,

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 15/25] drm/rockchip: vop2: Set correct output format for RK3576 YUV422
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli, Andy Yan
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

For RK3576 to be able to output YUV422 signals, it first needs to be
able to pick the right output mode in the display controller to do so.

The RK3576 hardware specifies different output formats depending on the
used display protocol.

Adjust the written register value based on the SoC and connector, so
other users of vcstate->output_mode don't have to care about this.

Reviewed-by: Andy Yan <andyshrk@163.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index 59d15bacf023..e76e00f0a530 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -1702,6 +1702,22 @@ static void vop2_crtc_atomic_enable(struct drm_crtc *crtc,
 	if (vcstate->output_mode == ROCKCHIP_OUT_MODE_AAAA &&
 	    !(vp_data->feature & VOP2_VP_FEATURE_OUTPUT_10BIT))
 		out_mode = ROCKCHIP_OUT_MODE_P888;
+	else if (vcstate->output_mode == ROCKCHIP_OUT_MODE_YUV422 &&
+		 vop2->version == VOP_VERSION_RK3576)
+		switch (vcstate->output_type) {
+		case DRM_MODE_CONNECTOR_DisplayPort:
+		case DRM_MODE_CONNECTOR_eDP:
+			out_mode = ROCKCHIP_OUT_MODE_YUV422_RK3576_DP;
+			break;
+		case DRM_MODE_CONNECTOR_HDMIA:
+			out_mode = ROCKCHIP_OUT_MODE_YUV422_RK3576_HDMI;
+			break;
+		default:
+			drm_err(vop2->drm, "Unknown DRM_MODE_CONNECTOR %d\n",
+				vcstate->output_type);
+			vop2_unlock(vop2);
+			return;
+		}
 	else
 		out_mode = vcstate->output_mode;
 

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 08/25] drm/amdgpu: Implement "color format" DRM property
From: Nicolas Frattaroli @ 2026-04-09 15:44 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli, Werner Sembach, Andri Yngvason, Marius Vlad
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

The "color format" DRM property allows userspace to explicitly pick a
color format to use. If an unsupported color format is requested,
userspace will be given an error instead of silently having its request
disobeyed.

The default case, which is AUTO, picks YCbCr 4:2:0 if it's a 4:2:0-only
mode, and RGB in all other cases.

Co-developed-by: Werner Sembach <wse@tuxedocomputers.com>
Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
Co-developed-by: Andri Yngvason <andri@yngvason.is>
Signed-off-by: Andri Yngvason <andri@yngvason.is>
Co-developed-by: Marius Vlad <marius.vlad@collabora.com>
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 90 ++++++++++++++++++++---
 1 file changed, 79 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index ad9714382d5f..ef9c60c49001 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6762,11 +6762,14 @@ static void fill_stream_properties_from_drm_display_mode(
 	const struct dc_stream_state *old_stream,
 	int requested_bpc)
 {
+	bool is_dp_or_hdmi = dc_is_hdmi_signal(stream->signal) || dc_is_dp_signal(stream->signal);
 	struct dc_crtc_timing *timing_out = &stream->timing;
 	const struct drm_display_info *info = &connector->display_info;
 	struct amdgpu_dm_connector *aconnector = NULL;
 	struct hdmi_vendor_infoframe hv_frame;
 	struct hdmi_avi_infoframe avi_frame;
+	bool want_420;
+	bool want_422;
 	ssize_t err;
 
 	if (connector->connector_type != DRM_MODE_CONNECTOR_WRITEBACK)
@@ -6779,20 +6782,41 @@ static void fill_stream_properties_from_drm_display_mode(
 	timing_out->h_border_right = 0;
 	timing_out->v_border_top = 0;
 	timing_out->v_border_bottom = 0;
-	/* TODO: un-hardcode */
-	if (drm_mode_is_420_only(info, mode_in) ||
-	    (aconnector && aconnector->force_yuv420_output &&
-	     drm_mode_is_420_also(info, mode_in)))
+
+	want_420 = (aconnector && aconnector->force_yuv420_output) ||
+		   (connector_state->color_format == DRM_CONNECTOR_COLOR_FORMAT_YCBCR420);
+	want_422 = (aconnector && aconnector->force_yuv422_output) ||
+		   (connector_state->color_format == DRM_CONNECTOR_COLOR_FORMAT_YCBCR422);
+
+	if (drm_mode_is_420_only(info, mode_in) &&
+	    (want_420 || connector_state->color_format == DRM_CONNECTOR_COLOR_FORMAT_AUTO)) {
 		timing_out->pixel_encoding = PIXEL_ENCODING_YCBCR420;
-	else if ((connector->display_info.color_formats & BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422))
-			&& aconnector
-			&& aconnector->force_yuv422_output)
+	} else if (drm_mode_is_420_also(info, mode_in) && want_420) {
+		timing_out->pixel_encoding = PIXEL_ENCODING_YCBCR420;
+	} else if ((info->color_formats & BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422)) &&
+		   want_422 && is_dp_or_hdmi) {
 		timing_out->pixel_encoding = PIXEL_ENCODING_YCBCR422;
-	else if ((connector->display_info.color_formats & BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444))
-			&& stream->signal == SIGNAL_TYPE_HDMI_TYPE_A)
+	} else if (connector_state->color_format == DRM_CONNECTOR_COLOR_FORMAT_YCBCR444 &&
+		   (info->color_formats & BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444)) &&
+		   is_dp_or_hdmi) {
 		timing_out->pixel_encoding = PIXEL_ENCODING_YCBCR444;
-	else
+	} else if (connector_state->color_format == DRM_CONNECTOR_COLOR_FORMAT_RGB444 ||
+		   connector_state->color_format == DRM_CONNECTOR_COLOR_FORMAT_AUTO) {
 		timing_out->pixel_encoding = PIXEL_ENCODING_RGB;
+	} else {
+		/*
+		 * If a format was explicitly requested but the requested format
+		 * can't be satisfied, set it to an invalid value so that an
+		 * error bubbles up to userspace. This way, userspace knows it
+		 * needs to make a better choice.
+		 */
+		if (connector_state->color_format != DRM_CONNECTOR_COLOR_FORMAT_AUTO)
+			timing_out->pixel_encoding = PIXEL_ENCODING_UNDEFINED;
+		else if (drm_mode_is_420_only(info, mode_in))
+			timing_out->pixel_encoding = PIXEL_ENCODING_YCBCR420;
+		else
+			timing_out->pixel_encoding = PIXEL_ENCODING_RGB;
+	}
 
 	timing_out->timing_3d_format = TIMING_3D_FORMAT_NONE;
 	timing_out->display_color_depth = convert_color_depth_from_display_info(
@@ -8142,6 +8166,38 @@ static enum dc_status dm_validate_stream_and_context(struct dc *dc,
 	return dc_result;
 }
 
+static enum dc_status
+dm_validate_stream_color_format(const struct drm_connector_state *drm_state,
+				const struct dc_stream_state *stream)
+{
+	enum dc_pixel_encoding encoding;
+
+	if (!drm_state->color_format)
+		return DC_OK;
+
+	switch (drm_state->color_format) {
+	case DRM_CONNECTOR_COLOR_FORMAT_AUTO:
+	case DRM_CONNECTOR_COLOR_FORMAT_RGB444:
+		encoding = PIXEL_ENCODING_RGB;
+		break;
+	case DRM_CONNECTOR_COLOR_FORMAT_YCBCR444:
+		encoding = PIXEL_ENCODING_YCBCR444;
+		break;
+	case DRM_CONNECTOR_COLOR_FORMAT_YCBCR422:
+		encoding = PIXEL_ENCODING_YCBCR422;
+		break;
+	case DRM_CONNECTOR_COLOR_FORMAT_YCBCR420:
+		encoding = PIXEL_ENCODING_YCBCR420;
+		break;
+	default:
+		encoding = PIXEL_ENCODING_UNDEFINED;
+		break;
+	}
+
+	return encoding == stream->timing.pixel_encoding ?
+		DC_OK : DC_UNSUPPORTED_VALUE;
+}
+
 struct dc_stream_state *
 create_validate_stream_for_sink(struct drm_connector *connector,
 				const struct drm_display_mode *drm_mode,
@@ -8188,6 +8244,9 @@ create_validate_stream_for_sink(struct drm_connector *connector,
 		if (dc_result == DC_OK)
 			dc_result = dm_validate_stream_and_context(adev->dm.dc, stream);
 
+		if (dc_result == DC_OK)
+			dc_result = dm_validate_stream_color_format(drm_state, stream);
+
 		if (dc_result != DC_OK) {
 			drm_dbg_kms(connector->dev, "Pruned mode %d x %d (clk %d) %s %s -- %s\n",
 				      drm_mode->hdisplay,
@@ -9017,6 +9076,12 @@ static const u32 supported_colorspaces =
 	BIT(DRM_MODE_COLORIMETRY_BT2020_RGB) |
 	BIT(DRM_MODE_COLORIMETRY_BT2020_YCC);
 
+static const u32 supported_colorformats =
+	BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR444) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR422) |
+	BIT(DRM_OUTPUT_COLOR_FORMAT_YCBCR420);
+
 void amdgpu_dm_connector_init_helper(struct amdgpu_display_manager *dm,
 				     struct amdgpu_dm_connector *aconnector,
 				     int connector_type,
@@ -9133,8 +9198,11 @@ void amdgpu_dm_connector_init_helper(struct amdgpu_display_manager *dm,
 	    connector_type == DRM_MODE_CONNECTOR_eDP) {
 		drm_connector_attach_hdr_output_metadata_property(&aconnector->base);
 
-		if (!aconnector->mst_root)
+		if (!aconnector->mst_root) {
 			drm_connector_attach_vrr_capable_property(&aconnector->base);
+			drm_connector_attach_color_format_property(&aconnector->base,
+								   supported_colorformats);
+		}
 
 		if (adev->dm.hdcp_workqueue)
 			drm_connector_attach_content_protection_property(&aconnector->base, true);

-- 
2.53.0



^ permalink raw reply related

* [PATCH v12 13/25] drm/rockchip: vop2: Add RK3576 to the RG swap special case
From: Nicolas Frattaroli @ 2026-04-09 15:45 UTC (permalink / raw)
  To: Harry Wentland, Leo Li, Rodrigo Siqueira, Alex Deucher,
	Christian König, David Airlie, Simona Vetter,
	Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann,
	Andrzej Hajda, Neil Armstrong, Robert Foss, Laurent Pinchart,
	Jonas Karlman, Jernej Skrabec, Sandy Huang, Heiko Stübner,
	Andy Yan, Jani Nikula, Rodrigo Vivi, Joonas Lahtinen,
	Tvrtko Ursulin, Dmitry Baryshkov, Sascha Hauer, Rob Herring,
	Jonathan Corbet, Shuah Khan
  Cc: kernel, amd-gfx, dri-devel, linux-kernel, linux-arm-kernel,
	linux-rockchip, intel-gfx, intel-xe, linux-doc,
	Nicolas Frattaroli, Andy Yan
In-Reply-To: <20260409-color-format-v12-0-ce84e1817a27@collabora.com>

Much like RK3588, RK3576 requires an RG swap to be performed for YUV444
8-bit and YUV444 10-bit bus formats.

Add its version to the already existing check for RK3588, so that YUV444
output is correct on this platform.

Fixes: 944757a4cba6 ("drm/rockchip: vop2: Add support for rk3576")
Reviewed-by: Andy Yan <andyshrk@163.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
index 843c7ef979b2..d3b76e7e785e 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
@@ -337,7 +337,8 @@ static bool vop2_output_uv_swap(u32 bus_format, u32 output_mode)
 
 static bool vop2_output_rg_swap(struct vop2 *vop2, u32 bus_format)
 {
-	if (vop2->version == VOP_VERSION_RK3588) {
+	if (vop2->version == VOP_VERSION_RK3588 ||
+	    vop2->version == VOP_VERSION_RK3576) {
 		if (bus_format == MEDIA_BUS_FMT_YUV8_1X24 ||
 		    bus_format == MEDIA_BUS_FMT_YUV10_1X30)
 			return true;

-- 
2.53.0



^ permalink raw reply related


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