RE: [PATCH] drm/amd/display: Fix deadlock during gpu reset v3

["Chen, Guchun" <Guchun.Chen@amd.com>]

[AMD Public Use]

Reviewed-by: Guchun Chen <guchun.chen@amd.com>

Regards,
Guchun

-----Original Message-----
From: Kazlauskas, Nicholas <Nicholas.Kazlauskas@amd.com> 
Sent: Wednesday, January 13, 2021 12:21 AM
To: Lakha, Bhawanpreet <Bhawanpreet.Lakha@amd.com>; Chen, Guchun <Guchun.Chen@amd.com>; Deucher, Alexander <Alexander.Deucher@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/amd/display: Fix deadlock during gpu reset v3

On 2021-01-12 11:13 a.m., Bhawanpreet Lakha wrote:
> [Why]
> during idle optimizations we acquire the dc_lock, this lock is also 
> acquired during gpu_reset so we end up hanging the system due to a 
> deadlock
> 
> [How]
> If we are in gpu reset:
>   - disable idle optimizations and skip calls to the dc function
> 
> v2: skip idle optimizations calls
> v3: add guard for DCN
> 
> Fixes: 06d5652541c3 ("drm/amd/display: enable idle optimizations for 
> linux (MALL stutter)")
> Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>

Regards,
Nicholas Kazlauskas

> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> 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 de71b6c21590..82ceb0a8ba29 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -1816,6 +1816,11 @@ static int dm_suspend(void *handle)
>   
>   	if (amdgpu_in_reset(adev)) {
>   		mutex_lock(&dm->dc_lock);
> +
> +#if defined(CONFIG_DRM_AMD_DC_DCN)
> +		dc_allow_idle_optimizations(adev->dm.dc, false); #endif
> +
>   		dm->cached_dc_state = dc_copy_state(dm->dc->current_state);
>   
>   		dm_gpureset_toggle_interrupts(adev, dm->cached_dc_state, false); 
> @@ -5556,6 +5561,10 @@ static inline int dm_set_vblank(struct drm_crtc *crtc, bool enable)
>   	if (!dc_interrupt_set(adev->dm.dc, irq_source, enable))
>   		return -EBUSY;
>   
> +#if defined(CONFIG_DRM_AMD_DC_DCN)
> +	if (amdgpu_in_reset(adev))
> +		return 0;
> +
>   	mutex_lock(&dm->dc_lock);
>   
>   	if (enable)
> @@ -5572,6 +5581,7 @@ static inline int dm_set_vblank(struct drm_crtc 
> *crtc, bool enable)
>   
>   	mutex_unlock(&dm->dc_lock);
>   
> +#endif
>   	return 0;
>   }
>   
> 
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