Re: [PATCH v3] usb: dwc3: core: Fix system suspend on TI AM62 platforms

[Roger Quadros <rogerq@kernel.org>]

Hi,

On 02/11/2024 14:34, Roger Quadros wrote:
> Hi William & Chris,
> 
> On 02/11/2024 13:50, Roger Quadros wrote:
>> Hi William,
>>
>> On 02/11/2024 01:08, William McVicker wrote:
>>> +linux-arm-msm@vger.kernel.org
>>>
>>> Hi Roger,
>>>
>>> On 10/11/2024, Roger Quadros wrote:
>>>> Since commit 6d735722063a ("usb: dwc3: core: Prevent phy suspend during init"),
>>>> system suspend is broken on AM62 TI platforms.
>>>>
>>>> Before that commit, both DWC3_GUSB3PIPECTL_SUSPHY and DWC3_GUSB2PHYCFG_SUSPHY
>>>> bits (hence forth called 2 SUSPHY bits) were being set during core
>>>> initialization and even during core re-initialization after a system
>>>> suspend/resume.
>>>>
>>>> These bits are required to be set for system suspend/resume to work correctly
>>>> on AM62 platforms.
>>>>
>>>> Since that commit, the 2 SUSPHY bits are not set for DEVICE/OTG mode if gadget
>>>> driver is not loaded and started.
>>>> For Host mode, the 2 SUSPHY bits are set before the first system suspend but
>>>> get cleared at system resume during core re-init and are never set again.
>>>>
>>>> This patch resovles these two issues by ensuring the 2 SUSPHY bits are set
>>>> before system suspend and restored to the original state during system resume.
>>>>
>>>> Cc: stable@vger.kernel.org # v6.9+
>>>> Fixes: 6d735722063a ("usb: dwc3: core: Prevent phy suspend during init")
>>>> Link: https://lore.kernel.org/all/1519dbe7-73b6-4afc-bfe3-23f4f75d772f@kernel.org/
>>>> Signed-off-by: Roger Quadros <rogerq@kernel.org>
>>>> Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
>>>> ---
>>>> Changes in v3:
>>>> - Fix single line comment style
>>>> - add DWC3_GUSB3PIPECTL_SUSPHY to documentation of susphy_state
>>>> - Added Acked-by tag
>>>> - Link to v2: https://lore.kernel.org/r/20241009-am62-lpm-usb-v2-1-da26c0cd2b1e@kernel.org
>>>>
>>>> Changes in v2:
>>>> - Fix comment style
>>>> - Use both USB3 and USB2 SUSPHY bits to determine susphy_state during system suspend/resume.
>>>> - Restore SUSPHY bits at system resume regardless if it was set or cleared before system suspend.
>>>> - Link to v1: https://lore.kernel.org/r/20241001-am62-lpm-usb-v1-1-9916b71165f7@kernel.org
>>>> ---
>>>>  drivers/usb/dwc3/core.c | 19 +++++++++++++++++++
>>>>  drivers/usb/dwc3/core.h |  3 +++
>>>>  2 files changed, 22 insertions(+)
>>>>
>>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>>> index 9eb085f359ce..ca77f0b186c4 100644
>>>> --- a/drivers/usb/dwc3/core.c
>>>> +++ b/drivers/usb/dwc3/core.c
>>>> @@ -2336,6 +2336,11 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>>>>  	u32 reg;
>>>>  	int i;
>>>>  
>>>> +	dwc->susphy_state = (dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
>>>> +			    DWC3_GUSB2PHYCFG_SUSPHY) ||
>>>> +			    (dwc3_readl(dwc->regs, DWC3_GUSB3PIPECTL(0)) &
>>>> +			    DWC3_GUSB3PIPECTL_SUSPHY);
>>>> +
>>>
>>> I'm running into an issue on my Pixel 6 device with this change when the
>>> dwc3-exynos device has runtime PM enabled. Basically, after the device boots up
>>> and I disconnect USB, the dwc3-exynos device enters runtime suspend followed by
>>> system suspend 15 seconds later. On system suspend, the clocks powering these
>>> dwc3 registers are off which results in an SError. I have verified that
>>> reverting this change fixes the issue.
>>>
>>> I noticed that dwc3-qcom.c also supports runtime PM for their dwc3 device and
>>> most likely is affected by this as well. It would be great if someone with a
>>> Qualcomm device could test out dwc3 suspend as well.
>>
>> Chris was facing another issue with this patch on Rockchip RK3566 [1]
>>
>> Looks like we totally missed the runtime suspended case
>> I'll think about a solution and send something by today.
>>
>> [1] - https://lore.kernel.org/all/671bef75.050a0220.e4bcd.1821@mx.google.com/
>>
>>>
>>> Here is the crash stack:
>>>
>>>   SError Interrupt on CPU7, code 0x00000000be000011 -- SError
>>>   CPU: 7 UID: 1000 PID: 5661 Comm: binder:477_1 Tainted: G        W  OE      6.12.0-rc3-android16-0-maybe-dirty-4k #1 0439eacb3cff642033630df7ee2e250e0625f2f0
>>>   96 irq, BUS_DATA0 group, 0x0
>>>   Tainted: [W]=WARN, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
>>>   Hardware name: Raven DVT (DT)
>>>   pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>>>   pc : readl+0x40/0x80
>>>   lr : readl+0x38/0x80
>>>   sp : ffffffc08baa39a0
>>>   x29: ffffffc08baa39a0 x28: ffffffd4dd140000 x27: ffffffd4dd140d70
>>>   x26: ffffffd4dd2b2000 x25: ffffff800cef2410 x24: ffffff800cef24c0
>>>   x23: ffffffd4dd24e000 x22: ffffff887df59440 x21: ffffffc085298100
>>>   x20: ffffffd4db8acf60 x19: ffffffc085298200 x18: ffffffc091b730b0
>>>   x17: 000000002a703c0b x16: 000000002a703c0b x15: 0000000000953000
>>>   x14: 0000000000000000 x13: 0000000000000030 x12: 0101010101010101
>>>   x11: 7f7f7f7f7f7fffff x10: 0000000000000000 x9 : ffffffd4dc0d7d48
>>>   x8 : 0000000000000000 x7 : 0000000000008000 x6 : 0000000000000000
>>>   x5 : 500020737562ffff x4 : 500020737562ffff x3 : ffffffd4db8acf60
>>>   x2 : ffffffd4db8a7bac x1 : ffffffc085298200 x0 : 0000000000000020
>>>   Kernel panic - not syncing: Asynchronous SError Interrupt
>>>   CPU: 7 UID: 1000 PID: 5661 Comm: binder:477_1 Tainted: G        W  OE      6.12.0-rc3-android16-0-maybe-dirty-4k #1 0439eacb3cff642033630df7ee2e250e0625f2f0
>>>   Tainted: [W]=WARN, [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
>>>   Hardware name: Raven DVT (DT)
>>>   Call trace:
>>>    dump_backtrace+0xec/0x128
>>>    show_stack+0x18/0x28
>>>    dump_stack_lvl+0x40/0x88
>>>    dump_stack+0x18/0x24
>>>    panic+0x134/0x45c
>>>    nmi_panic+0x3c/0x88
>>>    arm64_serror_panic+0x64/0x8c
>>>    do_serror+0xc4/0xc8
>>>    el1h_64_error_handler+0x34/0x48
>>>    el1h_64_error+0x68/0x6c
>>>    readl+0x40/0x80
>>>    dwc3_suspend_common+0x34/0x454
>>>    dwc3_suspend+0x20/0x40
>>>    platform_pm_suspend+0x40/0x90
>>>    dpm_run_callback+0x60/0x250
>>>    device_suspend+0x334/0x614
>>>    dpm_suspend+0xc4/0x368
>>>    dpm_suspend_start+0x90/0x100
>>>    suspend_devices_and_enter+0x128/0xad0
>>>    pm_suspend+0x354/0x650
>>>    state_store+0x104/0x144
>>>    kobj_attr_store+0x30/0x48
>>>    sysfs_kf_write+0x54/0x6c
>>>    kernfs_fop_write_iter+0x104/0x1e4
>>>    vfs_write+0x3bc/0x50c
>>>    ksys_write+0x78/0xe8
>>>    __arm64_sys_write+0x1c/0x2c
>>>    invoke_syscall+0x58/0x10c
>>>    el0_svc_common+0xa8/0xdc
>>>    do_el0_svc+0x1c/0x28
>>>    el0_svc+0x38/0x6c
>>>    el0t_64_sync_handler+0x70/0xbc
>>>    el0t_64_sync+0x1a8/0x1ac
>>>
> 
> Does this patch fix it for you?
> 
> From ee8b353523556a29a423261af9c15be261941ff8 Mon Sep 17 00:00:00 2001
> From: Roger Quadros <rogerq@kernel.org>
> Date: Sat, 2 Nov 2024 14:14:47 +0200
> Subject: [PATCH] usb: dwc3: fix fault at system suspend if device was already
>  runtime suspended
> 
> If the device was already runtime suspended then during system suspend
> we cannot access the device registers else it will crash.
> 
> Cc: stable@vger.kernel.org # v5.15+
> Reported-by: William McVicker <willmcvicker@google.com>
> Closes: https://lore.kernel.org/all/ZyVfcUuPq56R2m1Y@google.com
> Fixes: 705e3ce37bcc ("usb: dwc3: core: Fix system suspend on TI AM62 platforms")
> Signed-off-by: Roger Quadros <rogerq@kernel.org>
> ---
>  drivers/usb/dwc3/core.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 427e5660f87c..4933f1b4d9c6 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -2342,10 +2342,12 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>  	u32 reg;
>  	int i;
>  
> -	dwc->susphy_state = (dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
> -			    DWC3_GUSB2PHYCFG_SUSPHY) ||
> -			    (dwc3_readl(dwc->regs, DWC3_GUSB3PIPECTL(0)) &
> -			    DWC3_GUSB3PIPECTL_SUSPHY);
> +	if (!pm_runtime_suspended(dwc->dev)) {
> +		dwc->susphy_state = (dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
> +				    DWC3_GUSB2PHYCFG_SUSPHY) ||
> +				    (dwc3_readl(dwc->regs, DWC3_GUSB3PIPECTL(0)) &
> +				    DWC3_GUSB3PIPECTL_SUSPHY);
> +	}
>  
>  	switch (dwc->current_dr_role) {
>  	case DWC3_GCTL_PRTCAP_DEVICE:
> 
> base-commit: 4b57d665bce1306a2a887cb760aa0c0e7efb42ab

I think this is not sufficient to fix the issue as there is still a call
to dwc3_enable_susphy() in the end which needs to be avoided
if already runtime suspended.

-- 
cheers,
-roger