drm: Catch stop possible NULL pointer reference
This was caught by Weiss. Also added some comments to the
fb_changed and mode_changed variables to explain what they do.
Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Tested-by: Thomas White <taw@bitwiz.org.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 3da9cfa..6aaa2cb 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -706,8 +706,8 @@
struct drm_encoder **save_encoders, *new_encoder;
struct drm_framebuffer *old_fb = NULL;
bool save_enabled;
- bool mode_changed = false;
- bool fb_changed = false;
+ bool mode_changed = false; /* if true do a full mode set */
+ bool fb_changed = false; /* if true and !mode_changed just do a flip */
struct drm_connector *connector;
int count = 0, ro, fail = 0;
struct drm_crtc_helper_funcs *crtc_funcs;
@@ -758,6 +758,8 @@
if (set->crtc->fb == NULL) {
DRM_DEBUG("crtc has no fb, full mode set\n");
mode_changed = true;
+ } else if (set->fb == NULL) {
+ mode_changed = true;
} else if ((set->fb->bits_per_pixel !=
set->crtc->fb->bits_per_pixel) ||
set->fb->depth != set->crtc->fb->depth)