* Re: [PATCH] fbdev/pxafb: Fix multiple clamped values in pxafb_adjust_timing
From: Thorsten Blum @ 2025-12-02 18:36 UTC (permalink / raw)
To: Helge Deller
Cc: Chelsy Ratnawat, Thomas Zimmermann, Andy Shevchenko, Raag Jadav,
linux-fbdev, dri-devel, linux-kernel
In-Reply-To: <a7213b69-f6ae-4975-8c8b-2783dbe9f9b3@gmx.de>
On 2. Dec 2025, at 19:28, Helge Deller wrote:
> On 12/2/25 19:15, Thorsten Blum wrote:
>> The variables were never clamped because the return value of clamp_val()
>> was not used. Fix this by assigning the clamped values, and use clamp()
>> instead of clamp_val().
>> Cc: stable@vger.kernel.org
>> Fixes: 3f16ff608a75 ("[ARM] pxafb: cleanup of the timing checking code")
>> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
>> ---
>> drivers/video/fbdev/pxafb.c | 12 ++++++------
>> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> Thanks for the patch!
> It looks good, so I'll include it in the fbdev tree.
> Out of curiosity:
> How did you notice? Do you actually have the hardware and tested it?
I only compile-tested it.
I stumbled upon another driver with the same bug and then used grep to
search for other instances and found about 6 or 7, including this one.
Thanks,
Thorsten
^ permalink raw reply
* Re: [PATCH] fbdev/pxafb: Fix multiple clamped values in pxafb_adjust_timing
From: Helge Deller @ 2025-12-02 18:28 UTC (permalink / raw)
To: Thorsten Blum, Chelsy Ratnawat, Thomas Zimmermann,
Andy Shevchenko, Raag Jadav
Cc: linux-fbdev, dri-devel, linux-kernel
In-Reply-To: <20251202181600.511166-2-thorsten.blum@linux.dev>
On 12/2/25 19:15, Thorsten Blum wrote:
> The variables were never clamped because the return value of clamp_val()
> was not used. Fix this by assigning the clamped values, and use clamp()
> instead of clamp_val().
>
> Cc: stable@vger.kernel.org
> Fixes: 3f16ff608a75 ("[ARM] pxafb: cleanup of the timing checking code")
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
> drivers/video/fbdev/pxafb.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
Thanks for the patch!
It looks good, so I'll include it in the fbdev tree.
Out of curiosity:
How did you notice? Do you actually have the hardware and tested it?
Helge
> diff --git a/drivers/video/fbdev/pxafb.c b/drivers/video/fbdev/pxafb.c
> index b96a8a96bce8..e418eee825fb 100644
> --- a/drivers/video/fbdev/pxafb.c
> +++ b/drivers/video/fbdev/pxafb.c
> @@ -419,12 +419,12 @@ static int pxafb_adjust_timing(struct pxafb_info *fbi,
> var->yres = max_t(int, var->yres, MIN_YRES);
>
> if (!(fbi->lccr0 & LCCR0_LCDT)) {
> - clamp_val(var->hsync_len, 1, 64);
> - clamp_val(var->vsync_len, 1, 64);
> - clamp_val(var->left_margin, 1, 255);
> - clamp_val(var->right_margin, 1, 255);
> - clamp_val(var->upper_margin, 1, 255);
> - clamp_val(var->lower_margin, 1, 255);
> + var->hsync_len = clamp(var->hsync_len, 1, 64);
> + var->vsync_len = clamp(var->vsync_len, 1, 64);
> + var->left_margin = clamp(var->left_margin, 1, 255);
> + var->right_margin = clamp(var->right_margin, 1, 255);
> + var->upper_margin = clamp(var->upper_margin, 1, 255);
> + var->lower_margin = clamp(var->lower_margin, 1, 255);
> }
>
> /* make sure each line is aligned on word boundary */
^ permalink raw reply
* [PATCH] fbdev/pxafb: Fix multiple clamped values in pxafb_adjust_timing
From: Thorsten Blum @ 2025-12-02 18:15 UTC (permalink / raw)
To: Helge Deller, Chelsy Ratnawat, Thomas Zimmermann, Andy Shevchenko,
Raag Jadav
Cc: Thorsten Blum, stable, linux-fbdev, dri-devel, linux-kernel
The variables were never clamped because the return value of clamp_val()
was not used. Fix this by assigning the clamped values, and use clamp()
instead of clamp_val().
Cc: stable@vger.kernel.org
Fixes: 3f16ff608a75 ("[ARM] pxafb: cleanup of the timing checking code")
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
drivers/video/fbdev/pxafb.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/video/fbdev/pxafb.c b/drivers/video/fbdev/pxafb.c
index b96a8a96bce8..e418eee825fb 100644
--- a/drivers/video/fbdev/pxafb.c
+++ b/drivers/video/fbdev/pxafb.c
@@ -419,12 +419,12 @@ static int pxafb_adjust_timing(struct pxafb_info *fbi,
var->yres = max_t(int, var->yres, MIN_YRES);
if (!(fbi->lccr0 & LCCR0_LCDT)) {
- clamp_val(var->hsync_len, 1, 64);
- clamp_val(var->vsync_len, 1, 64);
- clamp_val(var->left_margin, 1, 255);
- clamp_val(var->right_margin, 1, 255);
- clamp_val(var->upper_margin, 1, 255);
- clamp_val(var->lower_margin, 1, 255);
+ var->hsync_len = clamp(var->hsync_len, 1, 64);
+ var->vsync_len = clamp(var->vsync_len, 1, 64);
+ var->left_margin = clamp(var->left_margin, 1, 255);
+ var->right_margin = clamp(var->right_margin, 1, 255);
+ var->upper_margin = clamp(var->upper_margin, 1, 255);
+ var->lower_margin = clamp(var->lower_margin, 1, 255);
}
/* make sure each line is aligned on word boundary */
--
Thorsten Blum <thorsten.blum@linux.dev>
GPG: 1D60 735E 8AEF 3BE4 73B6 9D84 7336 78FD 8DFE EAD4
^ permalink raw reply related
* Re: [PATCH 6.6.y] drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup
From: Greg KH @ 2025-12-02 15:53 UTC (permalink / raw)
To: Thomas Zimmermann
Cc: Sasha Levin, stable, Javier Martinez Canillas, Alex Deucher,
dri-devel, nouveau, amd-gfx, linux-fbdev
In-Reply-To: <250b44b3-e75b-4f8d-af44-d3a985ea554c@suse.de>
On Tue, Dec 02, 2025 at 08:42:52AM +0100, Thomas Zimmermann wrote:
> Hi,
>
> thanks for backporting.
>
> You also have to remove the calls to vga_switcheroo_client_fb_set() from
> these files
>
> https://elixir.bootlin.com/linux/v6.6/source/drivers/gpu/drm/i915/display/intel_fbdev.c
>
> https://elixir.bootlin.com/linux/v6.6/source/drivers/gpu/drm/radeon/radeon_fbdev.c
Also, a fixed backport would be appreciated here.
thanks
greg k-h
^ permalink raw reply
* Re: [PATCH 6.12.y] drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup
From: Greg KH @ 2025-12-02 15:52 UTC (permalink / raw)
To: Thomas Zimmermann
Cc: Sasha Levin, stable, Javier Martinez Canillas, Alex Deucher,
dri-devel, nouveau, amd-gfx, linux-fbdev
In-Reply-To: <4dd8e529-4777-4cfc-a536-dbe0d0a90419@suse.de>
On Tue, Dec 02, 2025 at 08:40:43AM +0100, Thomas Zimmermann wrote:
> Hi,
>
> thanks for backporting.
>
> You also have to remove the calls to vga_switcheroo_client_fb_set() from
> these files
>
> https://elixir.bootlin.com/linux/v6.12/source/drivers/gpu/drm/i915/display/intel_fbdev.c
> https://elixir.bootlin.com/linux/v6.12/source/drivers/gpu/drm/radeon/radeon_fbdev.c
Can you send a fixed up patch instead?
thanks,
greg k-h
^ permalink raw reply
* Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support
From: Frank Li @ 2025-12-02 14:53 UTC (permalink / raw)
To: Maud Spierings
Cc: Lee Jones, Daniel Thompson, Jingoo Han, Pavel Machek, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Helge Deller, Shawn Guo,
Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
Liam Girdwood, Mark Brown, dri-devel, linux-leds, devicetree,
linux-kernel, linux-fbdev, imx, linux-arm-kernel
In-Reply-To: <b9fe6df7-fdc6-4a32-919b-8f3b44eace7d@gocontroll.com>
On Tue, Dec 02, 2025 at 08:46:21AM +0100, Maud Spierings wrote:
> On 12/1/25 17:52, Frank Li wrote:
> > On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings via B4 Relay wrote:
> > > From: Maud Spierings <maudspierings@gocontroll.com>
> > >
> > > The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> > > with integrated boost controller.
> > >
> > > Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
> > >
> > > ---
> > >
> > > In the current implementation the control registers for channel 1,
> > > control all channels. So only one led subnode with led-sources is
> > > supported right now. If at some point the driver functionality is
> > > expanded the bindings can be easily extended with it.
> > > ---
> > > .../bindings/leds/backlight/maxim,max25014.yaml | 107 +++++++++++++++++++++
> > > MAINTAINERS | 5 +
> > > 2 files changed, 112 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > > new file mode 100644
> > > index 000000000000..e83723224b07
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > > @@ -0,0 +1,107 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Maxim max25014 backlight controller
> > > +
> > > +maintainers:
> > > + - Maud Spierings <maudspierings@gocontroll.com>
> > > +
> > > +properties:
> > > + compatible:
> > > + enum:
> > > + - maxim,max25014
> > > +
> > > + reg:
> > > + maxItems: 1
> > > +
> > > + "#address-cells":
> > > + const: 1
> > > +
> > > + "#size-cells":
> > > + const: 0
> > > +
> > > + enable-gpios:
> > > + maxItems: 1
> > > +
> > > + interrupts:
> > > + maxItems: 1
> > > +
> > > + power-supply:
> > > + description: Regulator which controls the boost converter input rail.
> > > +
> > > + pwms:
> > > + maxItems: 1
> > > +
> > > + maxim,iset:
> > > + $ref: /schemas/types.yaml#/definitions/uint32
> > > + maximum: 15
> > > + default: 11
> > > + description:
> > > + Value of the ISET field in the ISET register. This controls the current
> > > + scale of the outputs, a higher number means more current.
> > > +
> > > + led@0:
> >
> > define whole binding, allow 0-3. binding is not related with driver's
> > implement.
> >
> > it'd better put unders leds.
> >
>
> so like:
>
> backlight: backlight@6f {
> compatible = "maxim,max25014";
> reg = <0x6f>;
> enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> pinctrl-names = "default";
> pinctrl-0 = <&pinctrl_backlight>;
> maxim,iset = <7>;
>
> leds {
> #address-cells = <1>;
> #size-cells = <0>;
>
> led@0 {
> reg = <0>;
> led-sources = <0 1 2>;
> default-brightness = <50>;
> };
>
> optional led@#....
> };
> };
>
> right?
yes.
>
> Kind regards,
> Maud
>
> >
> > > + type: object
> > > + description: Properties for a string of connected LEDs.
> > > + $ref: common.yaml#
> > > +
> > > + properties:
> > > + reg:
> > > + const: 0
> > > +
> > > + led-sources:
> > > + allOf:
> > > + - minItems: 1
> > > + maxItems: 4
> > > + items:
> > > + minimum: 0
> > > + maximum: 3
> > > + default: [0, 1, 2, 3]
> > > +
> > > + default-brightness:
> > > + minimum: 0
> > > + maximum: 100
> > > + default: 50
> > > +
> > > + required:
> > > + - reg
> > > +
> > > + additionalProperties: false
> >
> > unevaluatedProperties: false because ref to common.yaml
> >
> > Frank
> >
>
>
^ permalink raw reply
* Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support
From: Maud Spierings @ 2025-12-02 7:46 UTC (permalink / raw)
To: Frank Li
Cc: Lee Jones, Daniel Thompson, Jingoo Han, Pavel Machek, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Helge Deller, Shawn Guo,
Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
Liam Girdwood, Mark Brown, dri-devel, linux-leds, devicetree,
linux-kernel, linux-fbdev, imx, linux-arm-kernel
In-Reply-To: <aS3H1qzSMKHamqpP@lizhi-Precision-Tower-5810>
On 12/1/25 17:52, Frank Li wrote:
> On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings via B4 Relay wrote:
>> From: Maud Spierings <maudspierings@gocontroll.com>
>>
>> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
>> with integrated boost controller.
>>
>> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
>>
>> ---
>>
>> In the current implementation the control registers for channel 1,
>> control all channels. So only one led subnode with led-sources is
>> supported right now. If at some point the driver functionality is
>> expanded the bindings can be easily extended with it.
>> ---
>> .../bindings/leds/backlight/maxim,max25014.yaml | 107 +++++++++++++++++++++
>> MAINTAINERS | 5 +
>> 2 files changed, 112 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>> new file mode 100644
>> index 000000000000..e83723224b07
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>> @@ -0,0 +1,107 @@
>> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Maxim max25014 backlight controller
>> +
>> +maintainers:
>> + - Maud Spierings <maudspierings@gocontroll.com>
>> +
>> +properties:
>> + compatible:
>> + enum:
>> + - maxim,max25014
>> +
>> + reg:
>> + maxItems: 1
>> +
>> + "#address-cells":
>> + const: 1
>> +
>> + "#size-cells":
>> + const: 0
>> +
>> + enable-gpios:
>> + maxItems: 1
>> +
>> + interrupts:
>> + maxItems: 1
>> +
>> + power-supply:
>> + description: Regulator which controls the boost converter input rail.
>> +
>> + pwms:
>> + maxItems: 1
>> +
>> + maxim,iset:
>> + $ref: /schemas/types.yaml#/definitions/uint32
>> + maximum: 15
>> + default: 11
>> + description:
>> + Value of the ISET field in the ISET register. This controls the current
>> + scale of the outputs, a higher number means more current.
>> +
>> + led@0:
>
> define whole binding, allow 0-3. binding is not related with driver's
> implement.
>
> it'd better put unders leds.
>
so like:
backlight: backlight@6f {
compatible = "maxim,max25014";
reg = <0x6f>;
enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_backlight>;
maxim,iset = <7>;
leds {
#address-cells = <1>;
#size-cells = <0>;
led@0 {
reg = <0>;
led-sources = <0 1 2>;
default-brightness = <50>;
};
optional led@#....
};
};
right?
Kind regards,
Maud
>
>> + type: object
>> + description: Properties for a string of connected LEDs.
>> + $ref: common.yaml#
>> +
>> + properties:
>> + reg:
>> + const: 0
>> +
>> + led-sources:
>> + allOf:
>> + - minItems: 1
>> + maxItems: 4
>> + items:
>> + minimum: 0
>> + maximum: 3
>> + default: [0, 1, 2, 3]
>> +
>> + default-brightness:
>> + minimum: 0
>> + maximum: 100
>> + default: 50
>> +
>> + required:
>> + - reg
>> +
>> + additionalProperties: false
>
> unevaluatedProperties: false because ref to common.yaml
>
> Frank
>
^ permalink raw reply
* Re: [PATCH 6.6.y] drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup
From: Thomas Zimmermann @ 2025-12-02 7:42 UTC (permalink / raw)
To: Sasha Levin, stable
Cc: Javier Martinez Canillas, Alex Deucher, dri-devel, nouveau,
amd-gfx, linux-fbdev
In-Reply-To: <20251201225123.1298682-1-sashal@kernel.org>
Hi,
thanks for backporting.
You also have to remove the calls to vga_switcheroo_client_fb_set() from
these files
https://elixir.bootlin.com/linux/v6.6/source/drivers/gpu/drm/i915/display/intel_fbdev.c
https://elixir.bootlin.com/linux/v6.6/source/drivers/gpu/drm/radeon/radeon_fbdev.c
Best regards
Thomas
Am 01.12.25 um 23:51 schrieb Sasha Levin:
> From: Thomas Zimmermann <tzimmermann@suse.de>
>
> [ Upstream commit eb76d0f5553575599561010f24c277cc5b31d003 ]
>
> Protect vga_switcheroo_client_fb_set() with console lock. Avoids OOB
> access in fbcon_remap_all(). Without holding the console lock the call
> races with switching outputs.
>
> VGA switcheroo calls fbcon_remap_all() when switching clients. The fbcon
> function uses struct fb_info.node, which is set by register_framebuffer().
> As the fb-helper code currently sets up VGA switcheroo before registering
> the framebuffer, the value of node is -1 and therefore not a legal value.
> For example, fbcon uses the value within set_con2fb_map() [1] as an index
> into an array.
>
> Moving vga_switcheroo_client_fb_set() after register_framebuffer() can
> result in VGA switching that does not switch fbcon correctly.
>
> Therefore move vga_switcheroo_client_fb_set() under fbcon_fb_registered(),
> which already holds the console lock. Fbdev calls fbcon_fb_registered()
> from within register_framebuffer(). Serializes the helper with VGA
> switcheroo's call to fbcon_remap_all().
>
> Although vga_switcheroo_client_fb_set() takes an instance of struct fb_info
> as parameter, it really only needs the contained fbcon state. Moving the
> call to fbcon initialization is therefore cleaner than before. Only amdgpu,
> i915, nouveau and radeon support vga_switcheroo. For all other drivers,
> this change does nothing.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Link: https://elixir.bootlin.com/linux/v6.17/source/drivers/video/fbdev/core/fbcon.c#L2942 # [1]
> Fixes: 6a9ee8af344e ("vga_switcheroo: initial implementation (v15)")
> Acked-by: Javier Martinez Canillas <javierm@redhat.com>
> Acked-by: Alex Deucher <alexander.deucher@amd.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: nouveau@lists.freedesktop.org
> Cc: amd-gfx@lists.freedesktop.org
> Cc: linux-fbdev@vger.kernel.org
> Cc: <stable@vger.kernel.org> # v2.6.34+
> Link: https://patch.msgid.link/20251105161549.98836-1-tzimmermann@suse.de
> [ drm_fb_helper_unregister_info() lacks vga_switcheroo code ]
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/gpu/drm/drm_fb_helper.c | 7 -------
> drivers/video/fbdev/core/fbcon.c | 9 +++++++++
> 2 files changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index b507c1c008a3e..3891837a78414 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -30,9 +30,7 @@
> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>
> #include <linux/console.h>
> -#include <linux/pci.h>
> #include <linux/sysrq.h>
> -#include <linux/vga_switcheroo.h>
>
> #include <drm/drm_atomic.h>
> #include <drm/drm_drv.h>
> @@ -1668,7 +1666,6 @@ static int drm_fb_helper_find_sizes(struct drm_fb_helper *fb_helper,
> static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper)
> {
> struct drm_client_dev *client = &fb_helper->client;
> - struct drm_device *dev = fb_helper->dev;
> struct drm_fb_helper_surface_size sizes;
> int ret;
>
> @@ -1687,10 +1684,6 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper)
>
> strcpy(fb_helper->fb->comm, "[fbcon]");
>
> - /* Set the fb info for vgaswitcheroo clients. Does nothing otherwise. */
> - if (dev_is_pci(dev->dev))
> - vga_switcheroo_client_fb_set(to_pci_dev(dev->dev), fb_helper->info);
> -
> return 0;
> }
>
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 78a5b22c8d150..8b2c3065c0c26 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -64,6 +64,7 @@
> #include <linux/console.h>
> #include <linux/string.h>
> #include <linux/kd.h>
> +#include <linux/pci.h>
> #include <linux/slab.h>
> #include <linux/fb.h>
> #include <linux/fbcon.h>
> @@ -75,6 +76,7 @@
> #include <linux/interrupt.h>
> #include <linux/crc32.h> /* For counting font checksums */
> #include <linux/uaccess.h>
> +#include <linux/vga_switcheroo.h>
> #include <asm/irq.h>
>
> #include "fbcon.h"
> @@ -2913,6 +2915,9 @@ void fbcon_fb_unregistered(struct fb_info *info)
>
> console_lock();
>
> + if (info->device && dev_is_pci(info->device))
> + vga_switcheroo_client_fb_set(to_pci_dev(info->device), NULL);
> +
> fbcon_registered_fb[info->node] = NULL;
> fbcon_num_registered_fb--;
>
> @@ -3046,6 +3051,10 @@ static int do_fb_registered(struct fb_info *info)
> }
> }
>
> + /* Set the fb info for vga_switcheroo clients. Does nothing otherwise. */
> + if (info->device && dev_is_pci(info->device))
> + vga_switcheroo_client_fb_set(to_pci_dev(info->device), info);
> +
> return ret;
> }
>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
^ permalink raw reply
* Re: [PATCH 6.12.y] drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup
From: Thomas Zimmermann @ 2025-12-02 7:40 UTC (permalink / raw)
To: Sasha Levin, stable
Cc: Javier Martinez Canillas, Alex Deucher, dri-devel, nouveau,
amd-gfx, linux-fbdev
In-Reply-To: <20251201221055.1281985-1-sashal@kernel.org>
Hi,
thanks for backporting.
You also have to remove the calls to vga_switcheroo_client_fb_set() from
these files
https://elixir.bootlin.com/linux/v6.12/source/drivers/gpu/drm/i915/display/intel_fbdev.c
https://elixir.bootlin.com/linux/v6.12/source/drivers/gpu/drm/radeon/radeon_fbdev.c
Best regards
Thomas
Am 01.12.25 um 23:10 schrieb Sasha Levin:
> From: Thomas Zimmermann <tzimmermann@suse.de>
>
> [ Upstream commit eb76d0f5553575599561010f24c277cc5b31d003 ]
>
> Protect vga_switcheroo_client_fb_set() with console lock. Avoids OOB
> access in fbcon_remap_all(). Without holding the console lock the call
> races with switching outputs.
>
> VGA switcheroo calls fbcon_remap_all() when switching clients. The fbcon
> function uses struct fb_info.node, which is set by register_framebuffer().
> As the fb-helper code currently sets up VGA switcheroo before registering
> the framebuffer, the value of node is -1 and therefore not a legal value.
> For example, fbcon uses the value within set_con2fb_map() [1] as an index
> into an array.
>
> Moving vga_switcheroo_client_fb_set() after register_framebuffer() can
> result in VGA switching that does not switch fbcon correctly.
>
> Therefore move vga_switcheroo_client_fb_set() under fbcon_fb_registered(),
> which already holds the console lock. Fbdev calls fbcon_fb_registered()
> from within register_framebuffer(). Serializes the helper with VGA
> switcheroo's call to fbcon_remap_all().
>
> Although vga_switcheroo_client_fb_set() takes an instance of struct fb_info
> as parameter, it really only needs the contained fbcon state. Moving the
> call to fbcon initialization is therefore cleaner than before. Only amdgpu,
> i915, nouveau and radeon support vga_switcheroo. For all other drivers,
> this change does nothing.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Link: https://elixir.bootlin.com/linux/v6.17/source/drivers/video/fbdev/core/fbcon.c#L2942 # [1]
> Fixes: 6a9ee8af344e ("vga_switcheroo: initial implementation (v15)")
> Acked-by: Javier Martinez Canillas <javierm@redhat.com>
> Acked-by: Alex Deucher <alexander.deucher@amd.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: nouveau@lists.freedesktop.org
> Cc: amd-gfx@lists.freedesktop.org
> Cc: linux-fbdev@vger.kernel.org
> Cc: <stable@vger.kernel.org> # v2.6.34+
> Link: https://patch.msgid.link/20251105161549.98836-1-tzimmermann@suse.de
> [ adapted dev->dev variable access ]
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> drivers/gpu/drm/drm_fb_helper.c | 6 ------
> drivers/video/fbdev/core/fbcon.c | 9 +++++++++
> 2 files changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index b15ddbd65e7b5..a8971c4eb9f05 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -30,9 +30,7 @@
> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>
> #include <linux/console.h>
> -#include <linux/pci.h>
> #include <linux/sysrq.h>
> -#include <linux/vga_switcheroo.h>
>
> #include <drm/drm_atomic.h>
> #include <drm/drm_drv.h>
> @@ -1637,10 +1635,6 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper)
>
> strcpy(fb_helper->fb->comm, "[fbcon]");
>
> - /* Set the fb info for vgaswitcheroo clients. Does nothing otherwise. */
> - if (dev_is_pci(dev->dev))
> - vga_switcheroo_client_fb_set(to_pci_dev(dev->dev), fb_helper->info);
> -
> return 0;
> }
>
> diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
> index 1fc1e47ae2b49..e681066736dea 100644
> --- a/drivers/video/fbdev/core/fbcon.c
> +++ b/drivers/video/fbdev/core/fbcon.c
> @@ -65,6 +65,7 @@
> #include <linux/string.h>
> #include <linux/kd.h>
> #include <linux/panic.h>
> +#include <linux/pci.h>
> #include <linux/printk.h>
> #include <linux/slab.h>
> #include <linux/fb.h>
> @@ -77,6 +78,7 @@
> #include <linux/interrupt.h>
> #include <linux/crc32.h> /* For counting font checksums */
> #include <linux/uaccess.h>
> +#include <linux/vga_switcheroo.h>
> #include <asm/irq.h>
>
> #include "fbcon.h"
> @@ -2894,6 +2896,9 @@ void fbcon_fb_unregistered(struct fb_info *info)
>
> console_lock();
>
> + if (info->device && dev_is_pci(info->device))
> + vga_switcheroo_client_fb_set(to_pci_dev(info->device), NULL);
> +
> fbcon_registered_fb[info->node] = NULL;
> fbcon_num_registered_fb--;
>
> @@ -3027,6 +3032,10 @@ static int do_fb_registered(struct fb_info *info)
> }
> }
>
> + /* Set the fb info for vga_switcheroo clients. Does nothing otherwise. */
> + if (info->device && dev_is_pci(info->device))
> + vga_switcheroo_client_fb_set(to_pci_dev(info->device), info);
> +
> return ret;
> }
>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
^ permalink raw reply
* [PATCH 6.6.y] drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup
From: Sasha Levin @ 2025-12-01 22:51 UTC (permalink / raw)
To: stable
Cc: Thomas Zimmermann, Javier Martinez Canillas, Alex Deucher,
dri-devel, nouveau, amd-gfx, linux-fbdev, Sasha Levin
In-Reply-To: <2025120119-quake-universal-d896@gregkh>
From: Thomas Zimmermann <tzimmermann@suse.de>
[ Upstream commit eb76d0f5553575599561010f24c277cc5b31d003 ]
Protect vga_switcheroo_client_fb_set() with console lock. Avoids OOB
access in fbcon_remap_all(). Without holding the console lock the call
races with switching outputs.
VGA switcheroo calls fbcon_remap_all() when switching clients. The fbcon
function uses struct fb_info.node, which is set by register_framebuffer().
As the fb-helper code currently sets up VGA switcheroo before registering
the framebuffer, the value of node is -1 and therefore not a legal value.
For example, fbcon uses the value within set_con2fb_map() [1] as an index
into an array.
Moving vga_switcheroo_client_fb_set() after register_framebuffer() can
result in VGA switching that does not switch fbcon correctly.
Therefore move vga_switcheroo_client_fb_set() under fbcon_fb_registered(),
which already holds the console lock. Fbdev calls fbcon_fb_registered()
from within register_framebuffer(). Serializes the helper with VGA
switcheroo's call to fbcon_remap_all().
Although vga_switcheroo_client_fb_set() takes an instance of struct fb_info
as parameter, it really only needs the contained fbcon state. Moving the
call to fbcon initialization is therefore cleaner than before. Only amdgpu,
i915, nouveau and radeon support vga_switcheroo. For all other drivers,
this change does nothing.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://elixir.bootlin.com/linux/v6.17/source/drivers/video/fbdev/core/fbcon.c#L2942 # [1]
Fixes: 6a9ee8af344e ("vga_switcheroo: initial implementation (v15)")
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Cc: dri-devel@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Cc: amd-gfx@lists.freedesktop.org
Cc: linux-fbdev@vger.kernel.org
Cc: <stable@vger.kernel.org> # v2.6.34+
Link: https://patch.msgid.link/20251105161549.98836-1-tzimmermann@suse.de
[ drm_fb_helper_unregister_info() lacks vga_switcheroo code ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/drm_fb_helper.c | 7 -------
drivers/video/fbdev/core/fbcon.c | 9 +++++++++
2 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index b507c1c008a3e..3891837a78414 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -30,9 +30,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/console.h>
-#include <linux/pci.h>
#include <linux/sysrq.h>
-#include <linux/vga_switcheroo.h>
#include <drm/drm_atomic.h>
#include <drm/drm_drv.h>
@@ -1668,7 +1666,6 @@ static int drm_fb_helper_find_sizes(struct drm_fb_helper *fb_helper,
static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper)
{
struct drm_client_dev *client = &fb_helper->client;
- struct drm_device *dev = fb_helper->dev;
struct drm_fb_helper_surface_size sizes;
int ret;
@@ -1687,10 +1684,6 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper)
strcpy(fb_helper->fb->comm, "[fbcon]");
- /* Set the fb info for vgaswitcheroo clients. Does nothing otherwise. */
- if (dev_is_pci(dev->dev))
- vga_switcheroo_client_fb_set(to_pci_dev(dev->dev), fb_helper->info);
-
return 0;
}
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 78a5b22c8d150..8b2c3065c0c26 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -64,6 +64,7 @@
#include <linux/console.h>
#include <linux/string.h>
#include <linux/kd.h>
+#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/fbcon.h>
@@ -75,6 +76,7 @@
#include <linux/interrupt.h>
#include <linux/crc32.h> /* For counting font checksums */
#include <linux/uaccess.h>
+#include <linux/vga_switcheroo.h>
#include <asm/irq.h>
#include "fbcon.h"
@@ -2913,6 +2915,9 @@ void fbcon_fb_unregistered(struct fb_info *info)
console_lock();
+ if (info->device && dev_is_pci(info->device))
+ vga_switcheroo_client_fb_set(to_pci_dev(info->device), NULL);
+
fbcon_registered_fb[info->node] = NULL;
fbcon_num_registered_fb--;
@@ -3046,6 +3051,10 @@ static int do_fb_registered(struct fb_info *info)
}
}
+ /* Set the fb info for vga_switcheroo clients. Does nothing otherwise. */
+ if (info->device && dev_is_pci(info->device))
+ vga_switcheroo_client_fb_set(to_pci_dev(info->device), info);
+
return ret;
}
--
2.51.0
^ permalink raw reply related
* [PATCH 6.12.y] drm, fbcon, vga_switcheroo: Avoid race condition in fbcon setup
From: Sasha Levin @ 2025-12-01 22:10 UTC (permalink / raw)
To: stable
Cc: Thomas Zimmermann, Javier Martinez Canillas, Alex Deucher,
dri-devel, nouveau, amd-gfx, linux-fbdev, Sasha Levin
In-Reply-To: <2025120119-edgy-recycled-bcfe@gregkh>
From: Thomas Zimmermann <tzimmermann@suse.de>
[ Upstream commit eb76d0f5553575599561010f24c277cc5b31d003 ]
Protect vga_switcheroo_client_fb_set() with console lock. Avoids OOB
access in fbcon_remap_all(). Without holding the console lock the call
races with switching outputs.
VGA switcheroo calls fbcon_remap_all() when switching clients. The fbcon
function uses struct fb_info.node, which is set by register_framebuffer().
As the fb-helper code currently sets up VGA switcheroo before registering
the framebuffer, the value of node is -1 and therefore not a legal value.
For example, fbcon uses the value within set_con2fb_map() [1] as an index
into an array.
Moving vga_switcheroo_client_fb_set() after register_framebuffer() can
result in VGA switching that does not switch fbcon correctly.
Therefore move vga_switcheroo_client_fb_set() under fbcon_fb_registered(),
which already holds the console lock. Fbdev calls fbcon_fb_registered()
from within register_framebuffer(). Serializes the helper with VGA
switcheroo's call to fbcon_remap_all().
Although vga_switcheroo_client_fb_set() takes an instance of struct fb_info
as parameter, it really only needs the contained fbcon state. Moving the
call to fbcon initialization is therefore cleaner than before. Only amdgpu,
i915, nouveau and radeon support vga_switcheroo. For all other drivers,
this change does nothing.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://elixir.bootlin.com/linux/v6.17/source/drivers/video/fbdev/core/fbcon.c#L2942 # [1]
Fixes: 6a9ee8af344e ("vga_switcheroo: initial implementation (v15)")
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Cc: dri-devel@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Cc: amd-gfx@lists.freedesktop.org
Cc: linux-fbdev@vger.kernel.org
Cc: <stable@vger.kernel.org> # v2.6.34+
Link: https://patch.msgid.link/20251105161549.98836-1-tzimmermann@suse.de
[ adapted dev->dev variable access ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/drm_fb_helper.c | 6 ------
drivers/video/fbdev/core/fbcon.c | 9 +++++++++
2 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index b15ddbd65e7b5..a8971c4eb9f05 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -30,9 +30,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/console.h>
-#include <linux/pci.h>
#include <linux/sysrq.h>
-#include <linux/vga_switcheroo.h>
#include <drm/drm_atomic.h>
#include <drm/drm_drv.h>
@@ -1637,10 +1635,6 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper)
strcpy(fb_helper->fb->comm, "[fbcon]");
- /* Set the fb info for vgaswitcheroo clients. Does nothing otherwise. */
- if (dev_is_pci(dev->dev))
- vga_switcheroo_client_fb_set(to_pci_dev(dev->dev), fb_helper->info);
-
return 0;
}
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 1fc1e47ae2b49..e681066736dea 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -65,6 +65,7 @@
#include <linux/string.h>
#include <linux/kd.h>
#include <linux/panic.h>
+#include <linux/pci.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/fb.h>
@@ -77,6 +78,7 @@
#include <linux/interrupt.h>
#include <linux/crc32.h> /* For counting font checksums */
#include <linux/uaccess.h>
+#include <linux/vga_switcheroo.h>
#include <asm/irq.h>
#include "fbcon.h"
@@ -2894,6 +2896,9 @@ void fbcon_fb_unregistered(struct fb_info *info)
console_lock();
+ if (info->device && dev_is_pci(info->device))
+ vga_switcheroo_client_fb_set(to_pci_dev(info->device), NULL);
+
fbcon_registered_fb[info->node] = NULL;
fbcon_num_registered_fb--;
@@ -3027,6 +3032,10 @@ static int do_fb_registered(struct fb_info *info)
}
}
+ /* Set the fb info for vga_switcheroo clients. Does nothing otherwise. */
+ if (info->device && dev_is_pci(info->device))
+ vga_switcheroo_client_fb_set(to_pci_dev(info->device), info);
+
return ret;
}
--
2.51.0
^ permalink raw reply related
* Re: [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support
From: Frank Li @ 2025-12-01 16:52 UTC (permalink / raw)
To: maudspierings
Cc: Lee Jones, Daniel Thompson, Jingoo Han, Pavel Machek, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Helge Deller, Shawn Guo,
Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
Liam Girdwood, Mark Brown, dri-devel, linux-leds, devicetree,
linux-kernel, linux-fbdev, imx, linux-arm-kernel
In-Reply-To: <20251201-max25014-v6-1-88e3ac8112ff@gocontroll.com>
On Mon, Dec 01, 2025 at 12:53:20PM +0100, Maud Spierings via B4 Relay wrote:
> From: Maud Spierings <maudspierings@gocontroll.com>
>
> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> with integrated boost controller.
>
> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
>
> ---
>
> In the current implementation the control registers for channel 1,
> control all channels. So only one led subnode with led-sources is
> supported right now. If at some point the driver functionality is
> expanded the bindings can be easily extended with it.
> ---
> .../bindings/leds/backlight/maxim,max25014.yaml | 107 +++++++++++++++++++++
> MAINTAINERS | 5 +
> 2 files changed, 112 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> new file mode 100644
> index 000000000000..e83723224b07
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> @@ -0,0 +1,107 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Maxim max25014 backlight controller
> +
> +maintainers:
> + - Maud Spierings <maudspierings@gocontroll.com>
> +
> +properties:
> + compatible:
> + enum:
> + - maxim,max25014
> +
> + reg:
> + maxItems: 1
> +
> + "#address-cells":
> + const: 1
> +
> + "#size-cells":
> + const: 0
> +
> + enable-gpios:
> + maxItems: 1
> +
> + interrupts:
> + maxItems: 1
> +
> + power-supply:
> + description: Regulator which controls the boost converter input rail.
> +
> + pwms:
> + maxItems: 1
> +
> + maxim,iset:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + maximum: 15
> + default: 11
> + description:
> + Value of the ISET field in the ISET register. This controls the current
> + scale of the outputs, a higher number means more current.
> +
> + led@0:
define whole binding, allow 0-3. binding is not related with driver's
implement.
it'd better put unders leds.
> + type: object
> + description: Properties for a string of connected LEDs.
> + $ref: common.yaml#
> +
> + properties:
> + reg:
> + const: 0
> +
> + led-sources:
> + allOf:
> + - minItems: 1
> + maxItems: 4
> + items:
> + minimum: 0
> + maximum: 3
> + default: [0, 1, 2, 3]
> +
> + default-brightness:
> + minimum: 0
> + maximum: 100
> + default: 50
> +
> + required:
> + - reg
> +
> + additionalProperties: false
unevaluatedProperties: false because ref to common.yaml
Frank
> +
> +required:
> + - compatible
> + - reg
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + #include <dt-bindings/gpio/gpio.h>
> + #include <dt-bindings/interrupt-controller/irq.h>
> +
> + i2c {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + backlight@6f {
> + compatible = "maxim,max25014";
> + reg = <0x6f>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> + enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> + interrupt-parent = <&gpio1>;
> + interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
> + power-supply = <®_backlight>;
> + pwms = <&pwm1>;
> + maxim,iset = <7>;
> +
> + led@0 {
> + reg = <0>;
> + led-sources = <0 1 2 3>;
> + default-brightness = <50>;
> + };
> + };
> + };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 58c7e3f678d8..606ce086f758 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15261,6 +15261,11 @@ F: Documentation/userspace-api/media/drivers/max2175.rst
> F: drivers/media/i2c/max2175*
> F: include/uapi/linux/max2175.h
>
> +MAX25014 BACKLIGHT DRIVER
> +M: Maud Spierings <maudspierings@gocontroll.com>
> +S: Maintained
> +F: Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> +
> MAX31335 RTC DRIVER
> M: Antoniu Miclaus <antoniu.miclaus@analog.com>
> L: linux-rtc@vger.kernel.org
>
> --
> 2.52.0
>
>
^ permalink raw reply
* Re: [PATCH 0/5] drm: Remove remaining support for kdb
From: Thomas Zimmermann @ 2025-12-01 16:41 UTC (permalink / raw)
To: simona, airlied, alexander.deucher, christian.koenig, lyude, dakr,
deller, mripard, maarten.lankhorst, jason.wessel, danielt,
dianders
Cc: dri-devel, amd-gfx, nouveau, linux-fbdev, linux-doc, linux-kernel
In-Reply-To: <20251125130634.1080966-1-tzimmermann@suse.de>
Series has been acked by Sima via IRC. Patches 4 and 5 have been r-b'ed.
https://people.freedesktop.org/~cbrill/dri-log/?channel=dri-devel&highlight_names=&date=2025-12-01&show_html=true
Am 25.11.25 um 13:52 schrieb Thomas Zimmermann:
> Remove the rest of the kbd support from DRM. Driver support has been
> broken for years without anyone complaining.
>
> Kdb cannot use regular DRM mode setting, so DRM drivers have to
> implement an additional hook to make it work (in theory). As outlined
> by Sima in commit 9c79e0b1d096 ("drm/fb-helper: Give up on kgdb for
> atomic drivers") from 2017, kdb is not compatible with DRM atomic mode
> setting. Non-atomic mode setting meanwhile has become rare.
>
> Only 3 DRM drivers implement the hooks for kdb support. Amdgpu and
> nouveau use non-atomic mode setting on older devices. But both drivers
> have switched to generic fbdev emulation, which isn't compatible with
> kdb. Radeon still runs kdb, but it doesn't work in practice. See the
> commits in this series for details
>
> Therefore remove the remaining support for kdb from the DRM drivers
> and from DRM fbdev emulation. Also remove the hooks from fbdev, as
> there are no fbdev drivers with kdb support.
>
> If we ever want to address kdb support within DRM drivers, a place to
> start would be the scanout buffers used by DRM's panic screen. These
> use the current display mode. They can be written and flushed without
> mode setting involved.
>
> Note: kdb over serial lines is not affected by this series and continues
> to work as before.
>
> Thomas Zimmermann (5):
> drm/amdgpu: Do not implement mode_set_base_atomic callback
> drm/nouveau: Do not implement mode_set_base_atomic callback
> drm/radeon: Do not implement mode_set_base_atomic callback
> drm/fbdev-helper: Remove drm_fb_helper_debug_enter/_leave()
> fbcon: Remove fb_debug_enter/_leave from struct fb_ops
>
> Documentation/process/debugging/kgdb.rst | 28 -----
> drivers/gpu/drm/amd/amdgpu/dce_v10_0.c | 35 ++-----
> drivers/gpu/drm/amd/amdgpu/dce_v6_0.c | 35 ++-----
> drivers/gpu/drm/amd/amdgpu/dce_v8_0.c | 35 ++-----
> drivers/gpu/drm/drm_fb_helper.c | 108 --------------------
> drivers/gpu/drm/nouveau/dispnv04/crtc.c | 24 +----
> drivers/gpu/drm/radeon/atombios_crtc.c | 74 ++++----------
> drivers/gpu/drm/radeon/radeon_legacy_crtc.c | 23 ++---
> drivers/gpu/drm/radeon/radeon_mode.h | 10 +-
> drivers/video/fbdev/core/fbcon.c | 24 -----
> drivers/video/fbdev/core/fbcon.h | 1 -
> include/drm/drm_fb_helper.h | 21 ----
> include/drm/drm_modeset_helper_vtables.h | 23 -----
> include/linux/fb.h | 4 -
> 14 files changed, 63 insertions(+), 382 deletions(-)
>
>
> base-commit: 0a21e96e0b6840d2a4e0b45a957679eeddeb4362
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
^ permalink raw reply
* Re: [PATCH v4 1/2] backlight: Add Congatec Board Controller (CGBC) backlight support
From: Thomas Richard @ 2025-12-01 13:13 UTC (permalink / raw)
To: petri.karhula, Lee Jones, Daniel Thompson, Jingoo Han,
Helge Deller
Cc: linux-kernel, dri-devel, linux-fbdev
In-Reply-To: <20251127-cgbc-backlight-v4-1-626523b7173d@novatron.fi>
On 11/27/25 4:21 PM, Petri Karhula via B4 Relay wrote:
> From: Petri Karhula <petri.karhula@novatron.fi>
>
> This driver provides backlight brightness control through the Linux
> backlight subsystem. It communicates with the board controller to
> adjust LCD backlight using PWM signals. Communication is done
> through Congatec Board Controller core driver.
Tested on a conga-SA7 module with conga-SEVAL carrier board.
Tested-by: Thomas Richard <thomas.richard@bootlin.com>
Best Regards,
Thomas
^ permalink raw reply
* [PATCH v6 4/4] arm64: dts: freescale: moduline-display-av123z7m-n17: add backlight
From: Maud Spierings via B4 Relay @ 2025-12-01 11:53 UTC (permalink / raw)
To: Lee Jones, Daniel Thompson, Jingoo Han, Pavel Machek, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Helge Deller, Shawn Guo,
Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
Liam Girdwood, Mark Brown
Cc: dri-devel, linux-leds, devicetree, linux-kernel, linux-fbdev, imx,
linux-arm-kernel, Maud Spierings
In-Reply-To: <20251201-max25014-v6-0-88e3ac8112ff@gocontroll.com>
From: Maud Spierings <maudspierings@gocontroll.com>
Add the missing backlight.
Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
...x8p-ml81-moduline-display-106-av123z7m-n17.dtso | 25 +++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso
index 3eb665ce9d5d..786a04ef40c8 100644
--- a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso
+++ b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso
@@ -16,6 +16,7 @@
panel {
compatible = "boe,av123z7m-n17";
+ backlight = <&backlight>;
enable-gpios = <&gpio1 7 GPIO_ACTIVE_HIGH>;
pinctrl-0 = <&pinctrl_panel>;
pinctrl-names = "default";
@@ -91,10 +92,32 @@ lvds1_out: endpoint {
};
};
- /* max25014 @ 0x6f */
+ backlight: backlight@6f {
+ compatible = "maxim,max25014";
+ reg = <0x6f>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_backlight>;
+ maxim,iset = <7>;
+
+ led@0 {
+ reg = <0>;
+ led-sources = <0 1 2 3>;
+ default-brightness = <50>;
+ };
+ };
};
&iomuxc {
+ pinctrl_backlight: backlightgrp {
+ fsl,pins = <
+ MX8MP_IOMUXC_GPIO1_IO04__GPIO1_IO04
+ (MX8MP_PULL_UP | MX8MP_PULL_ENABLE)
+ >;
+ };
+
pinctrl_lvds_bridge: lvdsbridgegrp {
fsl,pins = <
MX8MP_IOMUXC_SAI1_TXD2__GPIO4_IO14
--
2.52.0
^ permalink raw reply related
* [PATCH v6 2/4] backlight: add max25014atg backlight
From: Maud Spierings via B4 Relay @ 2025-12-01 11:53 UTC (permalink / raw)
To: Lee Jones, Daniel Thompson, Jingoo Han, Pavel Machek, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Helge Deller, Shawn Guo,
Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
Liam Girdwood, Mark Brown
Cc: dri-devel, linux-leds, devicetree, linux-kernel, linux-fbdev, imx,
linux-arm-kernel, Maud Spierings
In-Reply-To: <20251201-max25014-v6-0-88e3ac8112ff@gocontroll.com>
From: Maud Spierings <maudspierings@gocontroll.com>
The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
with integrated boost controller.
Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
MAINTAINERS | 1 +
drivers/video/backlight/Kconfig | 7 +
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/max25014.c | 419 +++++++++++++++++++++++++++++++++++++
4 files changed, 428 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index 606ce086f758..d082d3f8cfae 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15265,6 +15265,7 @@ MAX25014 BACKLIGHT DRIVER
M: Maud Spierings <maudspierings@gocontroll.com>
S: Maintained
F: Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
+F: drivers/video/backlight/max25014.c
MAX31335 RTC DRIVER
M: Antoniu Miclaus <antoniu.miclaus@analog.com>
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index d9374d208cee..d3bb6ccd4185 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -262,6 +262,13 @@ config BACKLIGHT_DA9052
help
Enable the Backlight Driver for DA9052-BC and DA9053-AA/Bx PMICs.
+config BACKLIGHT_MAX25014
+ tristate "Backlight driver for the Maxim MAX25014 chip"
+ depends on I2C
+ select REGMAP_I2C
+ help
+ If you are using a MAX25014 chip as a backlight driver say Y to enable it.
+
config BACKLIGHT_MAX8925
tristate "Backlight driver for MAX8925"
depends on MFD_MAX8925
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index dfbb169bf6ea..1170d9ec40b8 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_BACKLIGHT_LOCOMO) += locomolcd.o
obj-$(CONFIG_BACKLIGHT_LP855X) += lp855x_bl.o
obj-$(CONFIG_BACKLIGHT_LP8788) += lp8788_bl.o
obj-$(CONFIG_BACKLIGHT_LV5207LP) += lv5207lp.o
+obj-$(CONFIG_BACKLIGHT_MAX25014) += max25014.o
obj-$(CONFIG_BACKLIGHT_MAX8925) += max8925_bl.o
obj-$(CONFIG_BACKLIGHT_MP3309C) += mp3309c.o
obj-$(CONFIG_BACKLIGHT_MT6370) += mt6370-backlight.o
diff --git a/drivers/video/backlight/max25014.c b/drivers/video/backlight/max25014.c
new file mode 100644
index 000000000000..7000225752c3
--- /dev/null
+++ b/drivers/video/backlight/max25014.c
@@ -0,0 +1,419 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Backlight driver for Maxim MAX25014
+ *
+ * Copyright (C) 2025 GOcontroll B.V.
+ * Author: Maud Spierings <maudspierings@gocontroll.com>
+ */
+
+#include <linux/backlight.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define MAX25014_ISET_DEFAULT_100 11
+#define MAX_BRIGHTNESS 100
+#define MIN_BRIGHTNESS 0
+#define TON_MAX 130720 /* @153Hz */
+#define TON_STEP 1307 /* @153Hz */
+#define TON_MIN 0
+
+#define MAX25014_DEV_ID 0x00
+#define MAX25014_REV_ID 0x01
+#define MAX25014_ISET 0x02
+#define MAX25014_IMODE 0x03
+#define MAX25014_TON1H 0x04
+#define MAX25014_TON1L 0x05
+#define MAX25014_TON2H 0x06
+#define MAX25014_TON2L 0x07
+#define MAX25014_TON3H 0x08
+#define MAX25014_TON3L 0x09
+#define MAX25014_TON4H 0x0A
+#define MAX25014_TON4L 0x0B
+#define MAX25014_TON_1_4_LSB 0x0C
+#define MAX25014_SETTING 0x12
+#define MAX25014_DISABLE 0x13
+#define MAX25014_BSTMON 0x14
+#define MAX25014_IOUT1 0x15
+#define MAX25014_IOUT2 0x16
+#define MAX25014_IOUT3 0x17
+#define MAX25014_IOUT4 0x18
+#define MAX25014_OPEN 0x1B
+#define MAX25014_SHORT_GND 0x1C
+#define MAX25014_SHORT_LED 0x1D
+#define MAX25014_MASK 0x1E
+#define MAX25014_DIAG 0x1F
+
+#define MAX25014_ISET_ENA BIT(5)
+#define MAX25014_ISET_PSEN BIT(4)
+#define MAX25014_IMODE_HDIM BIT(2)
+#define MAX25014_SETTING_FPWM GENMASK(6, 4)
+#define MAX25014_DISABLE_DIS_MASK GENMASK(3, 0)
+#define MAX25014_DIAG_OT BIT(0)
+#define MAX25014_DIAG_OTW BIT(1)
+#define MAX25014_DIAG_HW_RST BIT(2)
+#define MAX25014_DIAG_BSTOV BIT(3)
+#define MAX25014_DIAG_BSTUV BIT(4)
+#define MAX25014_DIAG_IREFOOR BIT(5)
+
+struct max25014 {
+ struct i2c_client *client;
+ struct backlight_device *bl;
+ struct regmap *regmap;
+ struct gpio_desc *enable;
+ struct regulator *vin; /* regulator for boost converter Vin rail */
+ uint32_t iset;
+ uint8_t strings_mask;
+};
+
+static const struct regmap_config max25014_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .max_register = MAX25014_DIAG,
+};
+
+static int max25014_initial_power_state(struct max25014 *maxim)
+{
+ uint32_t val;
+ int ret;
+
+ ret = regmap_read(maxim->regmap, MAX25014_ISET, &val);
+ if (ret)
+ return ret;
+
+ return val & MAX25014_ISET_ENA ? BACKLIGHT_POWER_ON : BACKLIGHT_POWER_OFF;
+}
+
+static int max25014_check_errors(struct max25014 *maxim)
+{
+ uint32_t val;
+ uint8_t i;
+ int ret;
+
+ ret = regmap_read(maxim->regmap, MAX25014_OPEN, &val);
+ if (ret)
+ return ret;
+ if (val) {
+ dev_err(&maxim->client->dev, "Open led strings detected on:\n");
+ for (i = 0; i < 4; i++) {
+ if (val & 1 << i)
+ dev_err(&maxim->client->dev, "string %d\n", i + 1);
+ }
+ return -EIO;
+ }
+
+ ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
+ if (ret)
+ return ret;
+ if (val) {
+ dev_err(&maxim->client->dev, "Short to ground detected on:\n");
+ for (i = 0; i < 4; i++) {
+ if (val & 1 << i)
+ dev_err(&maxim->client->dev, "string %d\n", i + 1);
+ }
+ return -EIO;
+ }
+
+ ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
+ if (ret)
+ return ret;
+ if (val) {
+ dev_err(&maxim->client->dev, "Shorted led detected on:\n");
+ for (i = 0; i < 4; i++) {
+ if (val & 1 << i)
+ dev_err(&maxim->client->dev, "string %d\n", i + 1);
+ }
+ return -EIO;
+ }
+
+ ret = regmap_read(maxim->regmap, MAX25014_DIAG, &val);
+ if (ret)
+ return ret;
+ /*
+ * The HW_RST bit always starts at 1 after power up.
+ * It is reset on first read, does not indicate an error.
+ */
+ if (val && val != MAX25014_DIAG_HW_RST) {
+ if (val & MAX25014_DIAG_OT)
+ dev_err(&maxim->client->dev,
+ "Overtemperature shutdown\n");
+ if (val & MAX25014_DIAG_OTW)
+ dev_err(&maxim->client->dev,
+ "Chip is getting too hot (>125C)\n");
+ if (val & MAX25014_DIAG_BSTOV)
+ dev_err(&maxim->client->dev,
+ "Boost converter overvoltage\n");
+ if (val & MAX25014_DIAG_BSTUV)
+ dev_err(&maxim->client->dev,
+ "Boost converter undervoltage\n");
+ if (val & MAX25014_DIAG_IREFOOR)
+ dev_err(&maxim->client->dev, "IREF out of range\n");
+ return -EIO;
+ }
+ return 0;
+}
+
+/*
+ * 1. disable unused strings
+ * 2. set dim mode
+ * 3. set setting register
+ * 4. enable the backlight
+ */
+static int max25014_configure(struct max25014 *maxim, int initial_state)
+{
+ uint32_t val;
+ int ret;
+
+ /*
+ * Strings can only be disabled when MAX25014_ISET_ENA == 0, check if
+ * it needs to be changed at all to prevent the backlight flashing when
+ * it is configured correctly by the bootloader
+ */
+ ret = regmap_read(maxim->regmap, MAX25014_DISABLE, &val);
+ if (ret)
+ return ret;
+
+ if (!((val & MAX25014_DISABLE_DIS_MASK) == maxim->strings_mask)) {
+ if (initial_state == BACKLIGHT_POWER_ON) {
+ ret = regmap_write(maxim->regmap, MAX25014_ISET, 0);
+ if (ret)
+ return ret;
+ }
+ ret = regmap_write(maxim->regmap, MAX25014_DISABLE, maxim->strings_mask);
+ if (ret)
+ return ret;
+ }
+
+ ret = regmap_write(maxim->regmap, MAX25014_IMODE, MAX25014_IMODE_HDIM);
+ if (ret)
+ return ret;
+
+ ret = regmap_read(maxim->regmap, MAX25014_SETTING, &val);
+ if (ret)
+ return ret;
+
+ ret = regmap_write(maxim->regmap, MAX25014_SETTING,
+ val & ~MAX25014_SETTING_FPWM);
+ if (ret)
+ return ret;
+
+ ret = regmap_write(maxim->regmap, MAX25014_ISET,
+ maxim->iset | MAX25014_ISET_ENA |
+ MAX25014_ISET_PSEN);
+ return ret;
+}
+
+static int max25014_update_status(struct backlight_device *bl_dev)
+{
+ struct max25014 *maxim = bl_get_data(bl_dev);
+ uint32_t reg;
+ int ret;
+
+ if (backlight_is_blank(maxim->bl))
+ bl_dev->props.brightness = 0;
+
+ reg = TON_STEP * bl_dev->props.brightness;
+
+ /*
+ * 18 bit number lowest, 2 bits in first register,
+ * next lowest 8 in the L register, next 8 in the H register
+ * Seemingly setting the strength of only one string controls all of
+ * them, individual settings don't affect the outcome.
+ */
+
+ ret = regmap_write(maxim->regmap, MAX25014_TON_1_4_LSB, reg & 0b00000011);
+ if (ret != 0)
+ return ret;
+ ret = regmap_write(maxim->regmap, MAX25014_TON1L, (reg >> 2) & 0b11111111);
+ if (ret != 0)
+ return ret;
+ return regmap_write(maxim->regmap, MAX25014_TON1H, (reg >> 10) & 0b11111111);
+}
+
+static const struct backlight_ops max25014_bl_ops = {
+ .options = BL_CORE_SUSPENDRESUME,
+ .update_status = max25014_update_status,
+};
+
+static int max25014_parse_dt(struct max25014 *maxim,
+ uint32_t *initial_brightness)
+{
+ struct device *dev = &maxim->client->dev;
+ struct device_node *node = dev->of_node;
+ struct fwnode_handle *child;
+ uint32_t strings[4];
+ int res, i;
+
+ if (!node)
+ return dev_err_probe(dev, -EINVAL, "no platform data\n");
+
+ child = device_get_next_child_node(dev, NULL);
+ if (child) {
+ res = fwnode_property_count_u32(child, "led-sources");
+ if (res > 0) {
+ fwnode_property_read_u32_array(child, "led-sources",
+ strings, res);
+
+ /* set all strings as disabled, then enable those in led-sources*/
+ maxim->strings_mask = 0xf;
+ for (i = 0; i < res; i++) {
+ if (strings[i] <= 4)
+ maxim->strings_mask &= ~BIT(strings[i]);
+ }
+ }
+
+ fwnode_property_read_u32(child, "default-brightness",
+ initial_brightness);
+
+ fwnode_handle_put(child);
+ }
+
+ maxim->iset = MAX25014_ISET_DEFAULT_100;
+ of_property_read_u32(node, "maxim,iset", &maxim->iset);
+
+ if (maxim->iset > 15)
+ return dev_err_probe(dev, -EINVAL,
+ "Invalid iset, should be a value from 0-15, entered was %d\n",
+ maxim->iset);
+
+ if (*initial_brightness > 100)
+ return dev_err_probe(dev, -EINVAL,
+ "Invalid initial brightness, should be a value from 0-100, entered was %d\n",
+ *initial_brightness);
+
+ return 0;
+}
+
+static int max25014_probe(struct i2c_client *cl)
+{
+ const struct i2c_device_id *id = i2c_client_get_device_id(cl);
+ struct backlight_properties props;
+ uint32_t initial_brightness = 50;
+ struct backlight_device *bl;
+ struct max25014 *maxim;
+ int ret;
+
+ maxim = devm_kzalloc(&cl->dev, sizeof(struct max25014), GFP_KERNEL);
+ if (!maxim)
+ return -ENOMEM;
+
+ maxim->client = cl;
+
+ ret = max25014_parse_dt(maxim, &initial_brightness);
+ if (ret)
+ return ret;
+
+ maxim->vin = devm_regulator_get(&maxim->client->dev, "power");
+ if (IS_ERR(maxim->vin)) {
+ return dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->vin),
+ "failed to get power-supply");
+ }
+
+ ret = regulator_enable(maxim->vin);
+ if (ret)
+ return dev_err_probe(&maxim->client->dev, ret,
+ "failed to enable power-supply\n");
+
+ maxim->enable = devm_gpiod_get_optional(&maxim->client->dev, "enable",
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(maxim->enable)) {
+ ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->enable),
+ "failed to get enable gpio\n");
+ goto disable_vin;
+ }
+
+ /* Datasheet Electrical Characteristics tSTARTUP 2ms */
+ fsleep(2000);
+
+ maxim->regmap = devm_regmap_init_i2c(cl, &max25014_regmap_config);
+ if (IS_ERR(maxim->regmap)) {
+ ret = dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->regmap),
+ "failed to initialize the i2c regmap\n");
+ goto disable_full;
+ }
+
+ i2c_set_clientdata(cl, maxim);
+
+ ret = max25014_check_errors(maxim);
+ if (ret) { /* error is already reported in the above function */
+ goto disable_full;
+ }
+
+ ret = max25014_initial_power_state(maxim);
+ if (ret < 0) {
+ dev_err_probe(&maxim->client->dev, ret, "Could not get enabled state\n");
+ goto disable_full;
+ }
+
+ memset(&props, 0, sizeof(struct backlight_properties));
+ props.type = BACKLIGHT_PLATFORM;
+ props.max_brightness = MAX_BRIGHTNESS;
+ props.brightness = initial_brightness;
+ props.scale = BACKLIGHT_SCALE_LINEAR;
+ props.power = ret;
+
+ ret = max25014_configure(maxim, ret);
+ if (ret) {
+ dev_err_probe(&maxim->client->dev, ret, "device config error");
+ goto disable_full;
+ }
+
+ bl = devm_backlight_device_register(&maxim->client->dev, id->name,
+ &maxim->client->dev, maxim,
+ &max25014_bl_ops, &props);
+ if (IS_ERR(bl)) {
+ ret = dev_err_probe(&maxim->client->dev, PTR_ERR(bl),
+ "failed to register backlight\n");
+ goto disable_full;
+ }
+
+ maxim->bl = bl;
+
+ backlight_update_status(maxim->bl);
+
+ return 0;
+
+disable_full:
+ gpiod_set_value_cansleep(maxim->enable, 0);
+disable_vin:
+ regulator_disable(maxim->vin);
+ return ret;
+}
+
+static void max25014_remove(struct i2c_client *cl)
+{
+ struct max25014 *maxim = i2c_get_clientdata(cl);
+
+ maxim->bl->props.brightness = 0;
+ max25014_update_status(maxim->bl);
+ gpiod_set_value_cansleep(maxim->enable, 0);
+ regulator_disable(maxim->vin);
+}
+
+static const struct of_device_id max25014_dt_ids[] = {
+ { .compatible = "maxim,max25014", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, max25014_dt_ids);
+
+static const struct i2c_device_id max25014_ids[] = {
+ { "max25014" },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, max25014_ids);
+
+static struct i2c_driver max25014_driver = {
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .of_match_table = of_match_ptr(max25014_dt_ids),
+ },
+ .probe = max25014_probe,
+ .remove = max25014_remove,
+ .id_table = max25014_ids,
+};
+module_i2c_driver(max25014_driver);
+
+MODULE_DESCRIPTION("Maxim MAX25014 backlight driver");
+MODULE_AUTHOR("Maud Spierings <maudspierings@gocontroll.com>");
+MODULE_LICENSE("GPL");
--
2.52.0
^ permalink raw reply related
* [PATCH v6 3/4] arm64: dts: freescale: moduline-display-av101hdt-a10: add backlight
From: Maud Spierings via B4 Relay @ 2025-12-01 11:53 UTC (permalink / raw)
To: Lee Jones, Daniel Thompson, Jingoo Han, Pavel Machek, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Helge Deller, Shawn Guo,
Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
Liam Girdwood, Mark Brown
Cc: dri-devel, linux-leds, devicetree, linux-kernel, linux-fbdev, imx,
linux-arm-kernel, Maud Spierings
In-Reply-To: <20251201-max25014-v6-0-88e3ac8112ff@gocontroll.com>
From: Maud Spierings <maudspierings@gocontroll.com>
Add the missing backlight driver.
Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
...x8p-ml81-moduline-display-106-av101hdt-a10.dtso | 30 ++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso
index e3965caca6be..0e2914861154 100644
--- a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso
+++ b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso
@@ -17,6 +17,7 @@
panel {
compatible = "boe,av101hdt-a10";
+ backlight = <&backlight>;
enable-gpios = <&gpio1 7 GPIO_ACTIVE_HIGH>;
pinctrl-0 = <&pinctrl_panel>;
pinctrl-names = "default";
@@ -40,7 +41,36 @@ reg_vbus: regulator-vbus {
};
};
+&i2c4 {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ backlight: backlight@6f {
+ compatible = "maxim,max25014";
+ reg = <0x6f>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_backlight>;
+ maxim,iset = <7>;
+
+ led@0 {
+ reg = <0>;
+ led-sources = <0 1 2>;
+ default-brightness = <50>;
+ };
+ };
+};
+
&iomuxc {
+ pinctrl_backlight: backlightgrp {
+ fsl,pins = <
+ MX8MP_IOMUXC_GPIO1_IO04__GPIO1_IO04
+ (MX8MP_PULL_UP | MX8MP_PULL_ENABLE)
+ >;
+ };
+
pinctrl_panel: panelgrp {
fsl,pins = <
MX8MP_IOMUXC_GPIO1_IO07__GPIO1_IO07
--
2.52.0
^ permalink raw reply related
* [PATCH v6 1/4] dt-bindings: backlight: Add max25014 support
From: Maud Spierings via B4 Relay @ 2025-12-01 11:53 UTC (permalink / raw)
To: Lee Jones, Daniel Thompson, Jingoo Han, Pavel Machek, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Helge Deller, Shawn Guo,
Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
Liam Girdwood, Mark Brown
Cc: dri-devel, linux-leds, devicetree, linux-kernel, linux-fbdev, imx,
linux-arm-kernel, Maud Spierings
In-Reply-To: <20251201-max25014-v6-0-88e3ac8112ff@gocontroll.com>
From: Maud Spierings <maudspierings@gocontroll.com>
The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
with integrated boost controller.
Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
In the current implementation the control registers for channel 1,
control all channels. So only one led subnode with led-sources is
supported right now. If at some point the driver functionality is
expanded the bindings can be easily extended with it.
---
.../bindings/leds/backlight/maxim,max25014.yaml | 107 +++++++++++++++++++++
MAINTAINERS | 5 +
2 files changed, 112 insertions(+)
diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
new file mode 100644
index 000000000000..e83723224b07
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
@@ -0,0 +1,107 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim max25014 backlight controller
+
+maintainers:
+ - Maud Spierings <maudspierings@gocontroll.com>
+
+properties:
+ compatible:
+ enum:
+ - maxim,max25014
+
+ reg:
+ maxItems: 1
+
+ "#address-cells":
+ const: 1
+
+ "#size-cells":
+ const: 0
+
+ enable-gpios:
+ maxItems: 1
+
+ interrupts:
+ maxItems: 1
+
+ power-supply:
+ description: Regulator which controls the boost converter input rail.
+
+ pwms:
+ maxItems: 1
+
+ maxim,iset:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ maximum: 15
+ default: 11
+ description:
+ Value of the ISET field in the ISET register. This controls the current
+ scale of the outputs, a higher number means more current.
+
+ led@0:
+ type: object
+ description: Properties for a string of connected LEDs.
+ $ref: common.yaml#
+
+ properties:
+ reg:
+ const: 0
+
+ led-sources:
+ allOf:
+ - minItems: 1
+ maxItems: 4
+ items:
+ minimum: 0
+ maximum: 3
+ default: [0, 1, 2, 3]
+
+ default-brightness:
+ minimum: 0
+ maximum: 100
+ default: 50
+
+ required:
+ - reg
+
+ additionalProperties: false
+
+required:
+ - compatible
+ - reg
+
+additionalProperties: false
+
+examples:
+ - |
+ #include <dt-bindings/gpio/gpio.h>
+ #include <dt-bindings/interrupt-controller/irq.h>
+
+ i2c {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ backlight@6f {
+ compatible = "maxim,max25014";
+ reg = <0x6f>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+ interrupt-parent = <&gpio1>;
+ interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
+ power-supply = <®_backlight>;
+ pwms = <&pwm1>;
+ maxim,iset = <7>;
+
+ led@0 {
+ reg = <0>;
+ led-sources = <0 1 2 3>;
+ default-brightness = <50>;
+ };
+ };
+ };
diff --git a/MAINTAINERS b/MAINTAINERS
index 58c7e3f678d8..606ce086f758 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15261,6 +15261,11 @@ F: Documentation/userspace-api/media/drivers/max2175.rst
F: drivers/media/i2c/max2175*
F: include/uapi/linux/max2175.h
+MAX25014 BACKLIGHT DRIVER
+M: Maud Spierings <maudspierings@gocontroll.com>
+S: Maintained
+F: Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
+
MAX31335 RTC DRIVER
M: Antoniu Miclaus <antoniu.miclaus@analog.com>
L: linux-rtc@vger.kernel.org
--
2.52.0
^ permalink raw reply related
* [PATCH v6 0/4] backlight: add new max25014 backlight driver
From: Maud Spierings via B4 Relay @ 2025-12-01 11:53 UTC (permalink / raw)
To: Lee Jones, Daniel Thompson, Jingoo Han, Pavel Machek, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Helge Deller, Shawn Guo,
Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
Liam Girdwood, Mark Brown
Cc: dri-devel, linux-leds, devicetree, linux-kernel, linux-fbdev, imx,
linux-arm-kernel, Maud Spierings
The Maxim MAX25014 is an automotive grade backlight driver IC. Its
datasheet can be found at [1].
With its integrated boost controller, it can power 4 channels (led
strings) and has a number of different modes using pwm and or i2c.
Currently implemented is only i2c control.
link: https://www.analog.com/media/en/technical-documentation/data-sheets/MAX25014.pdf [1]
Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
Changes in v6:
- fixup changes in v4 where default brightness handling was changed but
not noted
- remove leftover comment about initializing brightness
- use BIT definitions for fields in the DIAG register
- apply reverse christmas tree initialization of local variables
- remove !=0 from checks, just check if (ret)
- remove > 0 from checks, just check if (val)
- use dev_err_probe() more
- set enable gpio high in the get() instead of seperately calling set()
- change usleep_range() to fsleep()
- remove null checks when setting gpio value
- get regular regulator, not optional to avoid further NULL checks in
case none is provided
- introduce max25014_initial_power_state() to check if the bootloader
has already initialized the backlight and to correctly set props.power
- squash max25014_register_control() into max25014_update_status()
- in max25014_configure() perform extra checking on the DISABLE register
now that the state from the bootloader is taken into account
- Link to v5: https://lore.kernel.org/r/20251107-max25014-v5-0-9a6aa57306bf@gocontroll.com
Changes in v5:
- moved comment about current functions of the driver to the actual
comment section of the commit
- fixed the led@0 property, regex patternProperty is not needed as of
now
- added extra clarification about the ISET field/register
- moved #address-cells and #size-cells to the correct location
- remove leftover default-brightness in backlight nodes
- Link to v4: https://lore.kernel.org/r/20251009-max25014-v4-0-6adb2a0aa35f@gocontroll.com
Changes in v4:
- remove setting default brightness, let backlight core take care of it
- use a led node to describe the backlight
- use led-sources to enable specific channels
- also wait 2ms when there is a supply but no enable
- change dev_warn() to dev_err() in error path in max25014_check_errors()
- set backlight_properties.scale to BACKLIGHT_SCALE_LINEAR
- rebase latest next
- add address-cells and size-cells to i2c4 in av101hdt-a10.dtso
- Link to v3: https://lore.kernel.org/r/20250911-max25014-v3-0-d03f4eba375e@gocontroll.com
Changes in v3:
- fixed commit message type intgrated -> integrated
- added maximum and description to maxim,iset-property
- dropped unused labels and pinctrl in bindings example
- put the compatible first in the bindings example and dts
- removed brackets around defines
- removed the leftover pdata struct field
- removed the initial_brightness struct field
- Link to v2: https://lore.kernel.org/r/20250819-max25014-v2-0-5fd7aeb141ea@gocontroll.com
Changes in v2:
- Remove leftover unused property from the bindings example
- Complete the bindings example with all properties
- Remove some double info from the maxim,iset property
- Remove platform_data header, fold its data into the max25014 struct
- Don't force defines to be unsigned
- Remove stray struct max25014 declaration
- Remove chipname and device from the max25014 struct
- Inline the max25014_backlight_register() and strings_mask() functions
- Remove CONFIG_OF ifdef
- Link to v1: https://lore.kernel.org/r/20250725-max25014-v1-0-0e8cce92078e@gocontroll.com
---
Maud Spierings (4):
dt-bindings: backlight: Add max25014 support
backlight: add max25014atg backlight
arm64: dts: freescale: moduline-display-av101hdt-a10: add backlight
arm64: dts: freescale: moduline-display-av123z7m-n17: add backlight
.../bindings/leds/backlight/maxim,max25014.yaml | 107 ++++++
MAINTAINERS | 6 +
...x8p-ml81-moduline-display-106-av101hdt-a10.dtso | 30 ++
...x8p-ml81-moduline-display-106-av123z7m-n17.dtso | 25 +-
drivers/video/backlight/Kconfig | 7 +
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/max25014.c | 419 +++++++++++++++++++++
7 files changed, 594 insertions(+), 1 deletion(-)
---
base-commit: 9c0826a5d9aa4d52206dd89976858457a2a8a7ed
change-id: 20250626-max25014-4207591e1af5
Best regards,
--
Maud Spierings <maudspierings@gocontroll.com>
^ permalink raw reply
* Re: [PATCH stable] fbdev: Fix out-of-bounds issue in sys_fillrect()
From: Gu Bowen @ 2025-12-01 9:25 UTC (permalink / raw)
To: Helge Deller; +Cc: linux-fbdev, dri-devel, Lu Jialin
In-Reply-To: <148a116a-b893-4e91-8573-1eebc2bb5c0e@gmx.de>
Hi,
On 11/15/2025 3:21 AM, Helge Deller wrote:
>
> That patch does not apply to git head.
> Can you try to reproduce with git head?
>
fbdev has already been refactored by commit eabb03293087 ("fbdev:
Refactoring the fbcon packed pixel drawing routines") on v6.15-rc1, so
this issue no longer exists in the mainline version. Similar question
has occurred in the past:
https://syzkaller.appspot.com/bug?extid=66bde8e1e4161d4b2cca
After the refactoring patch was merged, this issue did not reappear, but
it still exists in the stable version.
BR,
Guber
^ permalink raw reply
* Re: [PATCH v4 1/2] backlight: Add Congatec Board Controller (CGBC) backlight support
From: Thomas Richard @ 2025-11-29 10:27 UTC (permalink / raw)
To: petri.karhula, Lee Jones, Daniel Thompson, Jingoo Han,
Helge Deller
Cc: linux-kernel, dri-devel, linux-fbdev
In-Reply-To: <20251127-cgbc-backlight-v4-1-626523b7173d@novatron.fi>
On 11/27/25 4:21 PM, Petri Karhula via B4 Relay wrote:
> From: Petri Karhula <petri.karhula@novatron.fi>
>
> This driver provides backlight brightness control through the Linux
> backlight subsystem. It communicates with the board controller to
> adjust LCD backlight using PWM signals. Communication is done
> through Congatec Board Controller core driver.
>
[...]
> + bl_data->current_brightness = reply_buf[0] & BLT_PWM_DUTY_MASK;
> +
> + /* Verify the setting was applied correctly */
> + if (bl_data->current_brightness != brightness) {
> + dev_err(bl_data->dev,
> + "Brightness setting verification failed\n");
> + return -EIO;
> + }
I'm still not really convinced by other error messages, but okay let's
keep them. Maybe add current and requested brightnesses in this message,
it could be useful for debugging.
"Brightness setting verification failed (X instead of Y)"
Otherwise looks good to me. I will test your series
Reviewed-by: Thomas Richard <thomas.richard@bootlin.com>
Best Regards,
Thomas
^ permalink raw reply
* Re: [PATCH v4 1/2] backlight: Add Congatec Board Controller (CGBC) backlight support
From: Daniel Thompson @ 2025-11-27 15:55 UTC (permalink / raw)
To: petri.karhula
Cc: Thomas Richard, Lee Jones, Jingoo Han, Helge Deller, linux-kernel,
dri-devel, linux-fbdev
In-Reply-To: <20251127-cgbc-backlight-v4-1-626523b7173d@novatron.fi>
On Thu, Nov 27, 2025 at 03:21:59PM +0000, Petri Karhula via B4 Relay wrote:
> From: Petri Karhula <petri.karhula@novatron.fi>
>
> This driver provides backlight brightness control through the Linux
> backlight subsystem. It communicates with the board controller to
> adjust LCD backlight using PWM signals. Communication is done
> through Congatec Board Controller core driver.
>
> Signed-off-by: Petri Karhula <petri.karhula@novatron.fi>
Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
Daniel.
^ permalink raw reply
* [PATCH v4 2/2] mfd: cgbc: Add support for backlight
From: Petri Karhula via B4 Relay @ 2025-11-27 15:22 UTC (permalink / raw)
To: Thomas Richard, Lee Jones, Daniel Thompson, Jingoo Han,
Helge Deller
Cc: linux-kernel, dri-devel, linux-fbdev, Petri Karhula
In-Reply-To: <20251127-cgbc-backlight-v4-0-626523b7173d@novatron.fi>
From: Petri Karhula <petri.karhula@novatron.fi>
The Board Controller has control for display backlight.
Add backlight cell for the cgbc-backlight driver which
adds support for backlight brightness control.
Signed-off-by: Petri Karhula <petri.karhula@novatron.fi>
---
drivers/mfd/cgbc-core.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/mfd/cgbc-core.c b/drivers/mfd/cgbc-core.c
index 4782ff1114a9..10bb4b414c34 100644
--- a/drivers/mfd/cgbc-core.c
+++ b/drivers/mfd/cgbc-core.c
@@ -237,6 +237,7 @@ static struct mfd_cell cgbc_devs[] = {
{ .name = "cgbc-i2c", .id = 1 },
{ .name = "cgbc-i2c", .id = 2 },
{ .name = "cgbc-hwmon" },
+ { .name = "cgbc-backlight" },
};
static int cgbc_map(struct cgbc_device_data *cgbc)
--
2.34.1
^ permalink raw reply related
* [PATCH v4 1/2] backlight: Add Congatec Board Controller (CGBC) backlight support
From: Petri Karhula via B4 Relay @ 2025-11-27 15:21 UTC (permalink / raw)
To: Thomas Richard, Lee Jones, Daniel Thompson, Jingoo Han,
Helge Deller
Cc: linux-kernel, dri-devel, linux-fbdev, Petri Karhula
In-Reply-To: <20251127-cgbc-backlight-v4-0-626523b7173d@novatron.fi>
From: Petri Karhula <petri.karhula@novatron.fi>
This driver provides backlight brightness control through the Linux
backlight subsystem. It communicates with the board controller to
adjust LCD backlight using PWM signals. Communication is done
through Congatec Board Controller core driver.
Signed-off-by: Petri Karhula <petri.karhula@novatron.fi>
---
drivers/video/backlight/Kconfig | 11 +++
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/cgbc_bl.c | 179 ++++++++++++++++++++++++++++++++++++++
3 files changed, 191 insertions(+)
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index d9374d208cee..702f3b8ed036 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -249,6 +249,17 @@ config BACKLIGHT_PWM
If you have a LCD backlight adjustable by PWM, say Y to enable
this driver.
+config BACKLIGHT_CGBC
+ tristate "Congatec Board Controller (CGBC) backlight support"
+ depends on MFD_CGBC && X86
+ help
+ Say Y here to enable support for LCD backlight control on Congatec
+ x86-based boards via the CGBC (Congatec Board Controller).
+
+ This driver provides backlight brightness control through the Linux
+ backlight subsystem. It communicates with the board controller to
+ adjust LCD backlight using PWM signals.
+
config BACKLIGHT_DA903X
tristate "Backlight Driver for DA9030/DA9034 using WLED"
depends on PMIC_DA903X
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index dfbb169bf6ea..0169fd8873ed 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_BACKLIGHT_APPLE_DWI) += apple_dwi_bl.o
obj-$(CONFIG_BACKLIGHT_AS3711) += as3711_bl.o
obj-$(CONFIG_BACKLIGHT_BD6107) += bd6107.o
obj-$(CONFIG_BACKLIGHT_CLASS_DEVICE) += backlight.o
+obj-$(CONFIG_BACKLIGHT_CGBC) += cgbc_bl.o
obj-$(CONFIG_BACKLIGHT_DA903X) += da903x_bl.o
obj-$(CONFIG_BACKLIGHT_DA9052) += da9052_bl.o
obj-$(CONFIG_BACKLIGHT_EP93XX) += ep93xx_bl.o
diff --git a/drivers/video/backlight/cgbc_bl.c b/drivers/video/backlight/cgbc_bl.c
new file mode 100644
index 000000000000..74f80222d789
--- /dev/null
+++ b/drivers/video/backlight/cgbc_bl.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Congatec Board Controller (CGBC) Backlight Driver
+ *
+ * This driver provides backlight control for LCD displays connected to
+ * Congatec boards via the CGBC (Congatec Board Controller). It integrates
+ * with the Linux backlight subsystem and communicates with hardware through
+ * the cgbc-core module.
+ *
+ * Copyright (C) 2025 Novatron Oy
+ *
+ * Author: Petri Karhula <petri.karhula@novatron.fi>
+ */
+
+#include <linux/backlight.h>
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/mfd/cgbc.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define BLT_PWM_DUTY_MASK GENMASK(6, 0)
+
+/* CGBC command for PWM brightness control*/
+#define CGBC_CMD_BLT0_PWM 0x75
+
+#define CGBC_BL_MAX_BRIGHTNESS 100
+
+/**
+ * CGBC backlight driver data
+ * @dev: Pointer to the platform device
+ * @cgbc: Pointer to the parent CGBC device data
+ * @current_brightness: Current brightness level (0-100)
+ */
+struct cgbc_bl_data {
+ struct device *dev;
+ struct cgbc_device_data *cgbc;
+ unsigned int current_brightness;
+};
+
+static int cgbc_bl_read_brightness(struct cgbc_bl_data *bl_data)
+{
+ u8 cmd_buf[4] = { CGBC_CMD_BLT0_PWM };
+ u8 reply_buf[3];
+ int ret;
+
+ ret = cgbc_command(bl_data->cgbc, cmd_buf, sizeof(cmd_buf),
+ reply_buf, sizeof(reply_buf), NULL);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * Get only PWM duty factor percentage,
+ * ignore polarity inversion bit (bit 7)
+ */
+ bl_data->current_brightness = FIELD_GET(BLT_PWM_DUTY_MASK, reply_buf[0]);
+
+ return 0;
+}
+
+static int cgbc_bl_update_status(struct backlight_device *bl)
+{
+ struct cgbc_bl_data *bl_data = bl_get_data(bl);
+ u8 cmd_buf[4] = { CGBC_CMD_BLT0_PWM };
+ u8 reply_buf[3];
+ u8 brightness;
+ int ret;
+
+ brightness = backlight_get_brightness(bl);
+
+ if (brightness != bl_data->current_brightness) {
+ /* Read the current values */
+ ret = cgbc_command(bl_data->cgbc, cmd_buf, sizeof(cmd_buf), reply_buf,
+ sizeof(reply_buf), NULL);
+ if (ret < 0) {
+ dev_err(bl_data->dev, "Failed to read PWM settings: %d\n", ret);
+ return ret;
+ }
+
+ /*
+ * Prepare command buffer for writing new settings. Only 2nd byte is changed
+ * to set new brightness (PWM duty cycle %). Other values (polarity, frequency)
+ * are preserved from the read values.
+ */
+ cmd_buf[1] = (reply_buf[0] & ~BLT_PWM_DUTY_MASK) |
+ FIELD_PREP(BLT_PWM_DUTY_MASK, brightness);
+ cmd_buf[2] = reply_buf[1];
+ cmd_buf[3] = reply_buf[2];
+
+ ret = cgbc_command(bl_data->cgbc, cmd_buf, sizeof(cmd_buf), reply_buf,
+ sizeof(reply_buf), NULL);
+ if (ret < 0) {
+ dev_err(bl_data->dev, "Failed to set brightness: %d\n", ret);
+ return ret;
+ }
+
+ bl_data->current_brightness = reply_buf[0] & BLT_PWM_DUTY_MASK;
+
+ /* Verify the setting was applied correctly */
+ if (bl_data->current_brightness != brightness) {
+ dev_err(bl_data->dev,
+ "Brightness setting verification failed\n");
+ return -EIO;
+ }
+ }
+
+ return 0;
+}
+
+static int cgbc_bl_get_brightness(struct backlight_device *bl)
+{
+ struct cgbc_bl_data *bl_data = bl_get_data(bl);
+ int ret;
+
+ ret = cgbc_bl_read_brightness(bl_data);
+ if (ret < 0) {
+ dev_err(bl_data->dev, "Failed to read brightness: %d\n", ret);
+ return ret;
+ }
+
+ return bl_data->current_brightness;
+}
+
+static const struct backlight_ops cgbc_bl_ops = {
+ .options = BL_CORE_SUSPENDRESUME,
+ .update_status = cgbc_bl_update_status,
+ .get_brightness = cgbc_bl_get_brightness,
+};
+
+static int cgbc_bl_probe(struct platform_device *pdev)
+{
+ struct cgbc_device_data *cgbc = dev_get_drvdata(pdev->dev.parent);
+ struct backlight_properties props = { };
+ struct backlight_device *bl_dev;
+ struct cgbc_bl_data *bl_data;
+ int ret;
+
+ bl_data = devm_kzalloc(&pdev->dev, sizeof(*bl_data), GFP_KERNEL);
+ if (!bl_data)
+ return -ENOMEM;
+
+ bl_data->dev = &pdev->dev;
+ bl_data->cgbc = cgbc;
+
+ ret = cgbc_bl_read_brightness(bl_data);
+ if (ret < 0)
+ return dev_err_probe(&pdev->dev, ret,
+ "Failed to read initial brightness\n");
+
+ props.type = BACKLIGHT_PLATFORM;
+ props.max_brightness = CGBC_BL_MAX_BRIGHTNESS;
+ props.brightness = bl_data->current_brightness;
+ props.scale = BACKLIGHT_SCALE_LINEAR;
+
+ bl_dev = devm_backlight_device_register(&pdev->dev, "cgbc-backlight",
+ &pdev->dev, bl_data,
+ &cgbc_bl_ops, &props);
+ if (IS_ERR(bl_dev))
+ return dev_err_probe(&pdev->dev, PTR_ERR(bl_dev),
+ "Failed to register backlight device\n");
+
+ platform_set_drvdata(pdev, bl_data);
+
+ return 0;
+}
+
+static struct platform_driver cgbc_bl_driver = {
+ .driver = {
+ .name = "cgbc-backlight",
+ },
+ .probe = cgbc_bl_probe,
+};
+
+module_platform_driver(cgbc_bl_driver);
+
+MODULE_AUTHOR("Petri Karhula <petri.karhula@novatron.fi>");
+MODULE_DESCRIPTION("Congatec Board Controller (CGBC) Backlight Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:cgbc-backlight");
--
2.34.1
^ permalink raw reply related
* [PATCH v4 0/2] Backlight driver to control backlight behind Congatec Board Controller.
From: Petri Karhula via B4 Relay @ 2025-11-27 15:21 UTC (permalink / raw)
To: Thomas Richard, Lee Jones, Daniel Thompson, Jingoo Han,
Helge Deller
Cc: linux-kernel, dri-devel, linux-fbdev, Petri Karhula
This driver provides backlight brightness control through the Linux
backlight subsystem. It communicates with the board controller to
adjust LCD backlight using PWM signals. Communication is done
through Congatec Board Controller core driver.
Signed-off-by: Petri Karhula <petri.karhula@novatron.fi>
---
Changes in v4:
- Factor out brightness read into a helper
- Set backlight_properties.scale to BACKLIGHT_SCALE_LINEAR
- Link to v3: https://lore.kernel.org/r/20251125-cgbc-backlight-v3-0-18ae42689411@novatron.fi
Changes in v3:
- Fixed review comments and simplified the structure of the driver
- Link to v2: https://lore.kernel.org/r/20251119-cgbc-backlight-v2-0-4d4edd7ca662@novatron.fi
Changes in v2:
- Separated Board Controller core driver change into its own patch
- Link to v1: https://lore.kernel.org/r/20251118-cgbc-backlight-v1-1-cc6ac5301034@novatron.fi
---
Petri Karhula (2):
backlight: Add Congatec Board Controller (CGBC) backlight support
mfd: cgbc: Add support for backlight
drivers/mfd/cgbc-core.c | 1 +
drivers/video/backlight/Kconfig | 11 +++
drivers/video/backlight/Makefile | 1 +
drivers/video/backlight/cgbc_bl.c | 179 ++++++++++++++++++++++++++++++++++++++
4 files changed, 192 insertions(+)
---
base-commit: ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d
change-id: 20251118-cgbc-backlight-35c1109db0b8
Best regards,
--
Petri Karhula <petri.karhula@novatron.fi>
^ permalink raw reply
page: next (older) | prev (newer) | latest
- recent:[subjects (threaded)|topics (new)|topics (active)]
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox