Commit 9dc0487d authored Apr 13, 2016 by Lyude Committed by Dave Airlie Apr 27, 2016

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>

parent 263efde3

drivers/gpu/drm/drm_dp_mst_topology.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -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;