drm/dp: Wait up all outstanding tx waiters

As we can have multiple tx in the queue, with individual waiters, make
sure that all are woken when any state changes (so that we are sure the
right owner of the txmsg is woken).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170513105201.17658-2-chris@chris-wilson.co.uk

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -855,7 +855,7 @@ static void drm_dp_destroy_mst_branch_device(struct kref *kref)
 	mutex_unlock(&mstb->mgr->qlock);
 
 	if (wake_tx)
-		wake_up(&mstb->mgr->tx_waitq);
+		wake_up_all(&mstb->mgr->tx_waitq);
 
 	kref_put(kref, drm_dp_free_mst_branch_device);
 }
@@ -1510,7 +1510,7 @@ static void process_single_down_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
 		if (txmsg->seqno != -1)
 			txmsg->dst->tx_slots[txmsg->seqno] = NULL;
 		txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
-		wake_up(&mgr->tx_waitq);
+		wake_up_all(&mgr->tx_waitq);
 	}
 }
 
@@ -2258,7 +2258,7 @@ static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr)
 		mstb->tx_slots[slot] = NULL;
 		mutex_unlock(&mgr->qlock);
 
-		wake_up(&mgr->tx_waitq);
+		wake_up_all(&mgr->tx_waitq);
 	}
 	return ret;
 }