Merge tag 'arm-perf-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux into next/drivers

Merge "arm-cci PMU updates for 4.1" from Will Deacon:

CCI-400 PMU updates

This series reworks some of the CCI-400 PMU code so that it can be used
on both ARM and ARM64-based systems, without the need to boot in secure
mode on the latter. This paves the way for CCI-500 support in future.

* tag 'arm-perf-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux:
  arm-cci: Fix CCI PMU event validation
  arm-cci: Split the code for PMU vs driver support
  arm-cci: Get rid of secure transactions for PMU driver
  arm-cci: Abstract the CCI400 PMU specific definitions
  arm-cci: Rearrange code for splitting PMU vs driver code
  drivers: cci: reject groups spanning multiple HW PMUs
  + Linux 4.0-rc4

Signed-off-by: Olof Johansson <olof@lixom.net>

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 9a5b68717ec8..379ab4555756 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -733,10 +733,14 @@ static bool check_txmsg_state(struct drm_dp_mst_topology_mgr *mgr,
 			      struct drm_dp_sideband_msg_tx *txmsg)
 {
 	bool ret;
-	mutex_lock(&mgr->qlock);
+
+	/*
+	 * All updates to txmsg->state are protected by mgr->qlock, and the two
+	 * cases we check here are terminal states. For those the barriers
+	 * provided by the wake_up/wait_event pair are enough.
+	 */
 	ret = (txmsg->state == DRM_DP_SIDEBAND_TX_RX ||
 	       txmsg->state == DRM_DP_SIDEBAND_TX_TIMEOUT);
-	mutex_unlock(&mgr->qlock);
 	return ret;
 }
 
@@ -1363,12 +1367,13 @@ static int process_single_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
 	return 0;
 }
 
-/* must be called holding qlock */
 static void process_single_down_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
 {
 	struct drm_dp_sideband_msg_tx *txmsg;
 	int ret;
 
+	WARN_ON(!mutex_is_locked(&mgr->qlock));
+
 	/* construct a chunk from the first msg in the tx_msg queue */
 	if (list_empty(&mgr->tx_msg_downq)) {
 		mgr->tx_down_in_progress = false;