Re: [PATCH] drm/amd/display: Restore 5s vbl offdelay for NV3x+ DGPUs

[Mario Limonciello <mario.limonciello@amd.com>]

On 4/22/26 12:19, Leo Li wrote:
> 
> 
> On 2026-04-22 12:56, Alex Deucher wrote:
>> On Wed, Apr 22, 2026 at 12:49 PM <sunpeng.li@amd.com> wrote:
>>>
>>> From: Leo Li <sunpeng.li@amd.com>
>>>
>>> [Why]
>>>
>>> Rapid vblank off is causing flip-done timeouts for NV3x and newer
>>> family of GPUs that support more idle optimization features.
>>>
>>> A proper fix requires further investigation. In lieu of it, let's
>>> workaround it for now.
>>>
>>> [How]
>>>
>>> For NV3x and newer family of DGPUs, restore the old 5s vblank off timer.
>>>
>>> Fixes: 9b47278cec98 ("drm/amd/display: temp w/a for dGPU to enter idle optimizations")
>>> Link: https://gitlab.freedesktop.org/drm/amd/-/issues/3787
>>> Link: https://lore.kernel.org/amd-gfx/20260217191632.1243826-1-sysdadmin@m1k.cloud/
>>> Signed-off-by: Leo Li <sunpeng.li@amd.com>
>>> Tested-by: Michele Palazzi <sysdadmin@m1k.cloud>
>>> ---
>>>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c  | 18 +++++++++++++++---
>>>   1 file changed, 15 insertions(+), 3 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 3fa4dbda4517c..ce5063928413c 100644
>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>> @@ -9511,9 +9511,21 @@ static void manage_dm_interrupts(struct amdgpu_device *adev,
>>>          if (acrtc_state) {
>>>                  timing = &acrtc_state->stream->timing;
>>>
>>> -               if (amdgpu_ip_version(adev, DCE_HWIP, 0) <
>>> -                          IP_VERSION(3, 5, 0) ||
>>> -                          !(adev->flags & AMD_IS_APU)) {
>>> +               if (amdgpu_ip_version(adev, DCE_HWIP, 0) >=
>>> +                     IP_VERSION(3, 2, 0) &&
>>> +                     !(adev->flags & AMD_IS_APU)) {
>>
>> Why only dGPUs?  Seems like this is reported as least as often on APUs
>> if not more.
>>
>> Alex
> 
> Hi Alex, Mario,
> 
> At least in the case of the few reporters I was working with, this specific
> flip-done timeout was reproduced on NV3x and 4x systems running multi-display.
> The reporter for the linked gitlab issue was also running a nv3.
> 
> The cause of these flip timeouts can be varied. The signature for this
> particular issue was OTG failing to fire an interrupt that is expected to
> deliver the flip-done event. I'm not aware of this particular signature in APUs
> -- at least none on my radar. Do bring it to my attention if you're aware of
> them.
> 
> Thanks,
> Leo

In Michele's proposal 
(https://lore.kernel.org/amd-gfx/20260217191632.1243826-1-sysdadmin@m1k.cloud/) 
there was a mention that it was tested on DCN 3.5 too, which made me 
think that the exact same issue was on both.

Michele - can you readily reproduce the page flip timeout on DCN 3.5?

If so; could you modify Leo's patch to drop the IS_APU designation and 
see if it happens to be the same solution?

> 
>>
>>> +                       /*
>>> +                        * DGPUs NV3x and newer that support idle optimizations
>>> +                        * experience intermittent flip-done timeouts on cursor
>>> +                        * updates. Restore 5s offdelay behavior for now.
>>> +                        *
>>> +                        * Discussion on the issue:
>>> +                        * https://lore.kernel.org/amd-gfx/20260217191632.1243826-1-sysdadmin@m1k.cloud/
>>> +                        */
>>> +                       config.offdelay_ms = 5000;
>>> +                       config.disable_immediate = false;
>>> +               } else if (amdgpu_ip_version(adev, DCE_HWIP, 0) <
>>> +                            IP_VERSION(3, 5, 0)) {
>>>                          /*
>>>                           * Older HW and DGPU have issues with instant off;
>>>                           * use a 2 frame offdelay.
>>> --
>>> 2.53.0
>>>
>