Hi Jianqi,
On 09/12/24 12:06, jianqi.ren.cn@xxxxxxxxxxxxx wrote:
From: Wayne Lin <wayne.lin@xxxxxxx>
[ Upstream commit fcf6a49d79923a234844b8efe830a61f3f0584e4 ]
[Why]
When unplug one of monitors connected after mst hub, encounter null pointer dereference.
It's due to dc_sink get released immediately in early_unregister() or detect_ctx(). When
commit new state which directly referring to info stored in dc_sink will cause null pointer
dereference.
[how]
Remove redundant checking condition. Relevant condition should already be covered by checking
if dsc_aux is null or not. Also reset dsc_aux to NULL when the connector is disconnected.
Reviewed-by: Jerry Zuo <jerry.zuo@xxxxxxx>
Acked-by: Zaeem Mohamed <zaeem.mohamed@xxxxxxx>
Signed-off-by: Wayne Lin <wayne.lin@xxxxxxx>
Tested-by: Daniel Wheeler <daniel.wheeler@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Jianqi Ren <jianqi.ren.cn@xxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 1acef5f3838f..a1619f4569cf 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -183,6 +183,8 @@ amdgpu_dm_mst_connector_early_unregister(struct drm_connector *connector)
dc_sink_release(dc_sink);
aconnector->dc_sink = NULL;
aconnector->edid = NULL;
+ aconnector->dsc_aux = NULL;
+ port->passthrough_aux = NULL;
}
aconnector->mst_status = MST_STATUS_DEFAULT;
@@ -487,6 +489,8 @@ dm_dp_mst_detect(struct drm_connector *connector,
dc_sink_release(aconnector->dc_sink);
aconnector->dc_sink = NULL;
aconnector->edid = NULL;
+ aconnector->dsc_aux = NULL;
+ port->passthrough_aux = NULL;
amdgpu_dm_set_mst_status(&aconnector->mst_status,
MST_REMOTE_EDID | MST_ALLOCATE_NEW_PAYLOAD | MST_CLEAR_ALLOCATED_PAYLOAD,
This backport doesn't look right to me, can you please clarify these.
1. I think it is worth documenting in commit message just before your
SOB on why you don't need this hunk:
MST_REMOTE_EDID | MST_ALLOCATE_NEW_PAYLOAD |
MST_CLEAR_ALLOCATED_PAYLOAD,
@@ -1238,14 +1242,6 @@ 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++;
which is part of upstream, I understand that this is not in 6.1.y code,
if so is it even affected ?
2. Also commit message says:
""
Remove redundant checking condition. Relevant condition should already
be covered by checking if dsc_aux is null or not. Also reset dsc_aux to
NULL when the connector is disconnected.
""
but the if(!aconnector->dsc_aux) is not in 6.1.y, so something is
missing. Maybe 6.1.y is not affected or we need more backports to 6.1.y
to make them clean cherry-picks ?
Thanks,
Harshit
