Re: [PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: fcf6a49d79923a234844b8efe830a61f3f0584e4

WARNING: Author mismatch between patch and upstream commit:
Backport author: <jianqi.ren.cn@windriver.com>
Commit author: Wayne Lin<wayne.lin@amd.com>

Status in newer kernel trees:
6.14.y | Present (exact SHA1)
6.12.y | Present (exact SHA1)
6.6.y | Present (different SHA1: c7e65cab54a8)

Note: The patch differs from the upstream commit:
---
1:  fcf6a49d79923 ! 1:  a758fb74ab9a7 drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
    @@ Metadata
      ## Commit message ##
         drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
     
    +    [ Upstream commit fcf6a49d79923a234844b8efe830a61f3f0584e4 ]
    +
         [Why]
         When unplug one of monitors connected after mst hub, encounter null pointer dereference.
     
    @@ Commit message
         Signed-off-by: Wayne Lin <wayne.lin@amd.com>
         Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
         Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
    +    [The deleted codes in this fix is introduced by commit b9b5a82c5321
    +    ("drm/amd/display: Fix DSC-re-computing") after 6.11.]
    +    Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
    +    Signed-off-by: He Zhe <zhe.he@windriver.com>
     
      ## drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c ##
     @@ drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c: amdgpu_dm_mst_connector_early_unregister(struct drm_connector *connector)
    @@ drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c: dm_dp_mst_detect(st
      
      		amdgpu_dm_set_mst_status(&aconnector->mst_status,
      			MST_REMOTE_EDID | MST_ALLOCATE_NEW_PAYLOAD | MST_CLEAR_ALLOCATED_PAYLOAD,
    -@@ drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c: static bool is_dsc_need_re_compute(
    - 		if (!aconnector || !aconnector->dsc_aux)
    - 			continue;
    - 
    --		/*
    --		 *	check if cached virtual MST DSC caps are available and DSC is supported
    --		 *	as per specifications in their Virtual DPCD registers.
    --		*/
    --		if (!(aconnector->dc_sink->dsc_caps.dsc_dec_caps.is_dsc_supported ||
    --			aconnector->dc_link->dpcd_caps.dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_PASSTHROUGH_SUPPORT))
    --			continue;
    --
    - 		stream_on_link[new_stream_on_link_num] = aconnector;
    - 		new_stream_on_link_num++;
    - 
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |