[PATCH 38/73] drm/amd/display: Fix warnings on S3 resume

[Andrey Grodzovsky]

On 11/10/2017 01:38 PM, Andrey Grodzovsky wrote:
>
>
> On 11/09/2017 03:05 PM, Harry Wentland wrote:
>> From: "Leo (Sunpeng) Li" <sunpeng.li at amd.com>
>>
>> This is a followup to the following revert:
>>
>> Rex Zhu    Revert "drm/amd/display: Match actual state during S3
>>             resume."
>>
>> Three things needed to be addressed:
>>
>> 1. Potential memory leak on dc_state creation in atomic_check during
>>     s3 resume
>> 2. Warnings are now seen in dmesg during S3 resume
>> 3. Since dc_state is now created in atomic_check, what the reverted
>>     patch was addressing needs to be reevaluated.
>>
>> This change addresses the above:
>>
>> 1. Since the suspend procedure calls drm_atomic_state_clear, our hook
>>     for releasing the dc_state is called. This frees it before
>>     atomic_check creates it during resume. The leak does not occur.
>>
>> 2. The dc_crtc/plane_state references kept by the atomic states need to
>>     be released before calling atomic_check, which warns if they are
>>     non-null. This is because atomic_check is responsible for creating
>>     the dc_*_states. This is a special case for S3 resume, since the
>>     atomic state duplication that occurs during suspend also copies a
>>     reference to the dc_*_states.
>>
>> 3. See 2. comments are also updated to reflect this.
>>
>> Change-Id: I6e342bf8134f0e5dc32888a8d894c2cd20d28296
>> Signed-off-by: Leo (Sunpeng) Li <sunpeng.li at amd.com>
>> Reviewed-by: Harry Wentland <Harry.Wentland at amd.com>
>> ---
>>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 28 
>> +++++++++++++++++++++++
>>   1 file changed, 28 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 1c7f22146bc9..bdef1ed0dfac 100644
>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>> @@ -643,6 +643,11 @@ int amdgpu_dm_display_resume(struct 
>> amdgpu_device *adev)
>>       struct drm_connector *connector;
>>       struct drm_crtc *crtc;
>>       struct drm_crtc_state *new_crtc_state;
>> +    struct dm_crtc_state *dm_new_crtc_state;
>> +    struct drm_plane *plane;
>> +    struct drm_plane_state *new_plane_state;
>> +    struct dm_plane_state *dm_new_plane_state;
>> +
>>       int ret = 0;
>>       int i;
>>   @@ -685,6 +690,29 @@ int amdgpu_dm_display_resume(struct 
>> amdgpu_device *adev)
>>       for_each_new_crtc_in_state(adev->dm.cached_state, crtc, 
>> new_crtc_state, i)
>>           new_crtc_state->active_changed = true;
>>   +    /*
>> +     * atomic_check is expected to create the dc states. We need to 
>> release
>> +     * them here, since they were duplicated as part of the suspend
>> +     * procedure.
>> +     */
>> +    for_each_new_crtc_in_state(adev->dm.cached_state, crtc, 
>> new_crtc_state, i) {
>> +        dm_new_crtc_state = to_dm_crtc_state(new_crtc_state);
>> +        if (dm_new_crtc_state->stream) {
>> + WARN_ON(kref_read(&dm_new_crtc_state->stream->refcount) > 1);
>> +            dc_stream_release(dm_new_crtc_state->stream);
>> +            dm_new_crtc_state->stream = NULL;
>> +        }
>> +    }
>> +
>> +    for_each_new_plane_in_state(adev->dm.cached_state, plane, 
>> new_plane_state, i) {
>> +        dm_new_plane_state = to_dm_plane_state(new_plane_state);
>> +        if (dm_new_plane_state->dc_state) {
>> + WARN_ON(kref_read(&dm_new_plane_state->dc_state->refcount) > 1);
>> + dc_plane_state_release(dm_new_plane_state->dc_state);
>> +            dm_new_plane_state->dc_state = NULL;
>> +        }
>> +    }
>
> I guess the warnings you are referring to are in dm_update_crtcs_state 
> and dm_update_planes_state,
> but I don't understand why you need to explicitly release them in 
> amdgpu_dm_resume, any changed
> plane/crtc states will be removed during atomic check anyway and only 
> after that new one will be added,
> I find strange that this doesn't work.
>
> P.S I tried to reproduce this to see the warnings with latest 
> amd-staging-drm-next (776fb8c)on CZ but the system becomes
> unimpressive after going to suspend, might wanna check this on your side.

UNRESPONSIVE (it's unimpressive in any case :) )

Andrey

>
> Thanks,
> Andrey
>
>> +
>>       ret = drm_atomic_helper_resume(ddev, adev->dm.cached_state);
>>         drm_atomic_state_put(adev->dm.cached_state);
>
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