[PATCH] drm/amdgpu: Fix desktop freezed after gpu-reset

[André Almeida]

Hi Alan,

Em 14/04/2023 13:22, Alan Liu escreveu:
> [Why]
> After gpu-reset, sometimes the driver would fail to enable vblank irq,
> causing flip_done timed out and the desktop freezed.
> 
> During gpu-reset, we will disable and enable vblank irq in dm_suspend()
> and dm_resume(). Later on in amdgpu_irq_gpu_reset_resume_helper(), we
> will check irqs' refcount and decide to enable or disable the irqs
> again.
> 
> However, we have 2 sets of API for controling vblank irq, one is
> dm_vblank_get/put() and another is amdgpu_irq_get/put(). Each API has
> its own refcount and flag to store the state of vblank irq, and they
> are not synchronized.
> 
> In drm we use the first API to control vblank irq but in
> amdgpu_irq_gpu_reset_resume_helper() we use the second set of API.
> 
> The failure happens when vblank irq was enabled by dm_vblank_get()
> before gpu-reset, we have vblank->enabled true. However, during
> gpu-reset, in amdgpu_irq_gpu_reset_resume_helper(), vblank irq's state
> checked from amdgpu_irq_update() is DISABLED. So finally it will disable
> vblank irq again. After gpu-reset, if there is a cursor plane commit,
> the driver will try to enable vblank irq by calling drm_vblank_enable(),
> but the vblank->enabled is still true, so it fails to turn on vblank
> irq and causes flip_done can't be completed in vblank irq handler and
> desktop become freezed.
> 
> [How]
> Combining the 2 vblank control APIs by letting drm's API finally calls
> amdgpu_irq's API, so the irq's refcount and state of both APIs can be
> synchronized. Also add a check to prevent refcount from being less then
> 0 in amdgpu_irq_put().
> 

How have you tested this patch?

> v2:
> - Add warning in amdgpu_irq_enable() if the irq is already disabled.
> - Call dc_interrupt_set() in dm_set_vblank() to avoid refcount change
>    if it is in gpu-reset.
> 

If this is a v2, please use [PATCH v2] in the subject.

Thanks,
	André