drm/amd/display: Fix unstable HPCP compliance on Chrome Barcelo

[Why]
Intermittently, there presents two occurrences of 0 stream
commits in a single HPD event. Current HDCP sequence does
not consider such scenerio, and will thus disable HDCP.

[How]
Add condition check to include stream remove and re-enable
case for HDCP enable.

Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Acked-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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 24cd4c8..85d1304 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -8365,8 +8365,26 @@ static bool is_content_protection_different(struct drm_connector_state *state,
            state->content_protection == DRM_MODE_CONTENT_PROTECTION_ENABLED)
                state->content_protection = DRM_MODE_CONTENT_PROTECTION_DESIRED;
 
-       /* Check if something is connected/enabled, otherwise we start hdcp but nothing is connected/enabled
-        * hot-plug, headless s3, dpms
+       /* Stream removed and re-enabled
+        *
+        * Can sometimes overlap with the HPD case,
+        * thus set update_hdcp to false to avoid
+        * setting HDCP multiple times.
+        *
+        * Handles:     DESIRED -> DESIRED (Special case)
+        */
+       if (!(old_state->crtc && old_state->crtc->enabled) &&
+               state->crtc && state->crtc->enabled &&
+               connector->state->content_protection == DRM_MODE_CONTENT_PROTECTION_DESIRED) {
+               dm_con_state->update_hdcp = false;
+               return true;
+       }
+
+       /* Hot-plug, headless s3, dpms
+        *
+        * Only start HDCP if the display is connected/enabled.
+        * update_hdcp flag will be set to false until the next
+        * HPD comes in.
         *
         * Handles:     DESIRED -> DESIRED (Special case)
         */