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drm/dp/mst: Restore primary hub guid on resume 

Some hubs are forgetful, and end up forgetting whatever GUID we set
previously after we do a suspend/resume cycle. This can lead to
hotplugging breaking (along with probably other things) since the hub
will start sending connection notifications with the wrong GUID. As
such, we need to check on resume whether or not the GUID the hub is
giving us is valid.

Signed-off-by: Lyude <cpaul@redhat.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1460580618-7421-1-git-send-email-cpaul@redhat.com
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Lyude 2016-04-13 16:50:18 -04:00 committed by Dave Airlie
parent 263efde31f
commit 9dc0487d96
1 changed files with 12 additions and 0 deletions
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12
drivers/gpu/drm/drm_dp_mst_topology.c
View File

@ -2136,6 +2136,8 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr)
if (mgr->mst_primary) {
int sret;
u8 guid[16];
sret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd, DP_RECEIVER_CAP_SIZE);
if (sret != DP_RECEIVER_CAP_SIZE) {
DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n");
@ -2150,6 +2152,16 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr)
ret = -1;
goto out_unlock;
}
/* Some hubs forget their guids after they resume */
sret = drm_dp_dpcd_read(mgr->aux, DP_GUID, guid, 16);
if (sret != 16) {
DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n");
ret = -1;
goto out_unlock;
}
drm_dp_check_mstb_guid(mgr->mst_primary, guid);
ret = 0;
} else
ret = -1;