[PATCH 1/4] drm: try to restore previous CRTC config if mode set fails

[Jesse Barnes]

We restore the CRTC, encoder, and connector configurations, but if the
mode set failed, the attached display may have been turned off, so we
need to try set_config again to restore things to the way they were.

Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
---
 drivers/gpu/drm/drm_crtc_helper.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index f88a9b2..edaf903 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -479,6 +479,7 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
 	struct drm_connector *save_connectors, *connector;
 	int count = 0, ro, fail = 0;
 	struct drm_crtc_helper_funcs *crtc_funcs;
+	struct drm_mode_set save_set;
 	int ret = 0;
 	int i;
 
@@ -551,6 +552,12 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
 		save_connectors[count++] = *connector;
 	}
 
+	save_set.crtc = set->crtc;
+	save_set.mode = &set->crtc->mode;
+	save_set.x = set->crtc->x;
+	save_set.y = set->crtc->y;
+	save_set.fb = set->crtc->fb;
+
 	/* We should be able to check here if the fb has the same properties
 	 * and then just flip_or_move it */
 	if (set->crtc->fb != set->fb) {
@@ -716,6 +723,12 @@ fail:
 		*connector = save_connectors[count++];
 	}
 
+	/* Try to restore the config */
+	if (mode_changed &&
+	    !drm_crtc_helper_set_mode(save_set.crtc, save_set.mode, save_set.x,
+				      save_set.y, save_set.fb))
+		DRM_ERROR("failed to restore config after modeset failure\n");
+
 	kfree(save_connectors);
 	kfree(save_encoders);
 	kfree(save_crtcs);
-- 
1.7.4.1