[Intel-gfx] [PATCH 08/13] drm/i915: Use proper locking for intel_dp_check_link_status.

[Maarten Lankhorst]

To look at encoder->crtc->state the crtc mutex is required.
Get rid of connectors_active, and only check crtc state.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index cea7d1785d13..4b16023fffd0 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4235,19 +4235,17 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
 	struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
+	struct drm_crtc *crtc;
 	u8 sink_irq_vector;
 	u8 link_status[DP_LINK_STATUS_SIZE];
 
-	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
-
-	if (!intel_encoder->connectors_active)
-		return;
 
-	if (WARN_ON(!intel_encoder->base.crtc))
+	crtc = intel_encoder->base.crtc;
+	if (!crtc || !crtc->state->active)
 		return;
 
-	if (!to_intel_crtc(intel_encoder->base.crtc)->active)
-		return;
+	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
+	WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
 
 	/* Try to read receiver status if the link appears to be up */
 	if (!intel_dp_get_link_status(intel_dp, link_status)) {
@@ -4906,13 +4904,31 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
 		}
 
 		if (!intel_dp->is_mst) {
+			struct drm_modeset_acquire_ctx ctx;
+
+			drm_modeset_acquire_init(&ctx, 0);
+
+			while (1) {
+				int ret;
+
+				ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
+				if (!ret && intel_encoder->base.crtc)
+					ret = drm_modeset_lock(&intel_encoder->base.crtc->mutex, &ctx);
+
+				if (!ret || WARN_ON(ret != -EDEADLK))
+					break;
+
+				drm_modeset_backoff(&ctx);
+			}
+
 			/*
 			 * we'll check the link status via the normal hot plug path later -
 			 * but for short hpds we should check it now
 			 */
-			drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
 			intel_dp_check_link_status(intel_dp);
-			drm_modeset_unlock(&dev->mode_config.connection_mutex);
+
+			drm_modeset_drop_locks(&ctx);
+			drm_modeset_acquire_fini(&ctx);
 		}
 	}
 
-- 
2.1.0