Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1356020

[PATCH 2/2] drm/i915: Retry after 30ms if we fail to resume DP MST

Show all headers | View raw

For whatever reason, I've found that some laptops aren't immediately
capable of doing aux transactions with their docks when they come out of
standby. While I'm still not entirely sure what the cause of this is,
sleeping for 30ms and then retrying drm_dp_mst_topology_mgr_resume()
should be a sufficient enough workaround until we find a real fix.

CC: stable@vger.kernel.org
Signed-off-by: Lyude <cpaul@redhat.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 1d8de43..8cc5f6f 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -6114,6 +6114,19 @@ void intel_dp_mst_resume(struct drm_device *dev)
 
 			ret = drm_dp_mst_topology_mgr_resume(&intel_dig_port->dp.mst_mgr);
 			if (ret != 0) {
+				/*
+				 * For some reason, some laptops can't bring
+				 * their MST docks back up immediately after
+				 * resume and need to wait a short period of
+				 * time before aux transactions with the dock
+				 * become functional again. Until we find a
+				 * proper fix for this, this workaround should
+				 * suffice
+				 */
+				msleep(30);
+				ret = drm_dp_mst_topology_mgr_resume(&intel_dig_port->dp.mst_mgr);
+			}
+			if (ret != 0) {
 				intel_dp_check_mst_status(&intel_dig_port->dp);
 			}
 		}
-- 
2.5.0

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

[PATCH 0/2] Workaround for MST displays failing to come back after resume Lyude <cpaul@redhat.com> - 2016-03-11 17:00 +0100
  [PATCH 2/2] drm/i915: Retry after 30ms if we fail to resume DP MST Lyude <cpaul@redhat.com> - 2016-03-11 17:00 +0100

csiph-web