drm: Make the connector dpms callback return a value, v2.

This is required to properly handle failing dpms calls.
When making a wait in i915 interruptible, I've noticed
that the dpms sequence could fail with -ERESTARTSYS because
it was waiting interruptibly for flips. So from now on
allow drivers to fail in their connector dpms callback.

Encoder and crtc dpms callbacks are unaffected.

Changes since v1:
- Update kerneldoc for the drm helper functions.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
[danvet: Resolve conflicts due to different merge order.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 16 insertions, 12 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 5ec13c7cc832..57847ae8ce8c 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1974,9 +1974,12 @@ EXPORT_SYMBOL(drm_atomic_helper_page_flip);
  * implementing the legacy DPMS connector interface. It computes the new desired
  * ->active state for the corresponding CRTC (if the connector is enabled) and
  *  updates it.
+ *
+ * Returns:
+ * Returns 0 on success, negative errno numbers on failure.
  */
-void drm_atomic_helper_connector_dpms(struct drm_connector *connector,
-				      int mode)
+int drm_atomic_helper_connector_dpms(struct drm_connector *connector,
+				     int mode)
 {
 	struct drm_mode_config *config = &connector->dev->mode_config;
 	struct drm_atomic_state *state;
@@ -1985,6 +1988,7 @@ void drm_atomic_helper_connector_dpms(struct drm_connector *connector,
 	struct drm_connector *tmp_connector;
 	int ret;
 	bool active = false;
+	int old_mode = connector->dpms;
 
 	if (mode != DRM_MODE_DPMS_ON)
 		mode = DRM_MODE_DPMS_OFF;
@@ -1993,18 +1997,19 @@ void drm_atomic_helper_connector_dpms(struct drm_connector *connector,
 	crtc = connector->state->crtc;
 
 	if (!crtc)
-		return;
+		return 0;
 
-	/* FIXME: ->dpms has no return value so can't forward the -ENOMEM. */
 	state = drm_atomic_state_alloc(connector->dev);
 	if (!state)
-		return;
+		return -ENOMEM;
 
 	state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
 retry:
 	crtc_state = drm_atomic_get_crtc_state(state, crtc);
-	if (IS_ERR(crtc_state))
-		return;
+	if (IS_ERR(crtc_state)) {
+		ret = PTR_ERR(crtc_state);
+		goto fail;
+	}
 
 	WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));
 
@@ -2023,17 +2028,16 @@ retry:
 	if (ret != 0)
 		goto fail;
 
-	/* Driver takes ownership of state on successful async commit. */
-	return;
+	/* Driver takes ownership of state on successful commit. */
+	return 0;
 fail:
 	if (ret == -EDEADLK)
 		goto backoff;
 
+	connector->dpms = old_mode;
 	drm_atomic_state_free(state);
 
-	WARN(1, "Driver bug: Changing ->active failed with ret=%i\n", ret);
-
-	return;
+	return ret;
 backoff:
 	drm_atomic_state_clear(state);
 	drm_atomic_legacy_backoff(state);