drm/atomic: Acquire connection_mutex lock in drm_helper_probe_single_connector_modes, v4.

mode_valid() called from drm_helper_probe_single_connector_modes()
may need to look at connector->state because what a valid mode is may
depend on connector properties being set. For example some HDMI modes
might be rejected when a connector property forces the connector
into DVI mode.

Some implementations of detect() already lock all state,
so we have to pass an acquire_ctx to them to prevent a deadlock.

This means changing the function signature of detect() slightly,
and passing the acquire_ctx for locking multiple crtc's.
For the callbacks, it will always be non-zero. To allow callers
not to worry about this, drm_helper_probe_detect_ctx is added
which might handle -EDEADLK for you.

Changes since v1:
- Always set ctx parameter.
Changes since v2:
- Always take connection_mutex when probing.
Changes since v3:
- Remove the ctx from intel_dp_long_pulse, and add
  WARN_ON(!connection_mutex) (danvet)
- Update docs to clarify the locking situation. (danvet)

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1491504920-4017-1-git-send-email-maarten.lankhorst@linux.intel.com

1 files changed, 9 insertions, 12 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index fd96a6cf7326..6e04cb54e3ff 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4566,7 +4566,7 @@ intel_dp_unset_edid(struct intel_dp *intel_dp)
 	intel_dp->has_audio = false;
 }
 
-static enum drm_connector_status
+static int
 intel_dp_long_pulse(struct intel_connector *intel_connector)
 {
 	struct drm_connector *connector = &intel_connector->base;
@@ -4577,6 +4577,8 @@ intel_dp_long_pulse(struct intel_connector *intel_connector)
 	enum drm_connector_status status;
 	u8 sink_irq_vector = 0;
 
+	WARN_ON(!drm_modeset_is_locked(&connector->dev->mode_config.connection_mutex));
+
 	intel_display_power_get(to_i915(dev), intel_dp->aux_power_domain);
 
 	/* Can't disconnect eDP, but you can close the lid... */
@@ -4635,14 +4637,7 @@ intel_dp_long_pulse(struct intel_connector *intel_connector)
 		status = connector_status_disconnected;
 		goto out;
 	} else if (connector->status == connector_status_connected) {
-		/*
-		 * If display was connected already and is still connected
-		 * check links status, there has been known issues of
-		 * link loss triggerring long pulse!!!!
-		 */
-		drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
 		intel_dp_check_link_status(intel_dp);
-		drm_modeset_unlock(&dev->mode_config.connection_mutex);
 		goto out;
 	}
 
@@ -4682,11 +4677,13 @@ out:
 	return status;
 }
 
-static enum drm_connector_status
-intel_dp_detect(struct drm_connector *connector, bool force)
+static int
+intel_dp_detect(struct drm_connector *connector,
+		struct drm_modeset_acquire_ctx *ctx,
+		bool force)
 {
 	struct intel_dp *intel_dp = intel_attached_dp(connector);
-	enum drm_connector_status status = connector->status;
+	int status = connector->status;
 
 	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
 		      connector->base.id, connector->name);
@@ -5014,7 +5011,6 @@ void intel_dp_encoder_reset(struct drm_encoder *encoder)
 
 static const struct drm_connector_funcs intel_dp_connector_funcs = {
 	.dpms = drm_atomic_helper_connector_dpms,
-	.detect = intel_dp_detect,
 	.force = intel_dp_force,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.set_property = intel_dp_set_property,
@@ -5027,6 +5023,7 @@ static const struct drm_connector_funcs intel_dp_connector_funcs = {
 };
 
 static const struct drm_connector_helper_funcs intel_dp_connector_helper_funcs = {
+	.detect_ctx = intel_dp_detect,
 	.get_modes = intel_dp_get_modes,
 	.mode_valid = intel_dp_mode_valid,
 };