drm: review locking for drm_fb_helper_restore_fbdev_mode
... it's required. Fix up exynos and the cma helper, and add a
corresponding WARN_ON to drm_fb_helper_restore_fbdev_mode.
Note that tegra calls the fbdev cma helper restore function also from
it's driver-load callback. Which is a bit against current practice,
since usually the call is only from ->lastclose, and initial setup is
done by drm_fb_helper_initial_config.
Also add the relevant drm DocBook entry.
v2: Add promised WARN to restore_fbdev_mode.
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 0c6e25e..77378a1 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -239,10 +239,21 @@
}
EXPORT_SYMBOL(drm_fb_helper_debug_leave);
+/**
+ * drm_fb_helper_restore_fbdev_mode - restore fbdev configuration
+ * @fb_helper: fbcon to restore
+ *
+ * This should be called from driver's drm->lastclose callback when implementing
+ * an fbcon on top of kms using this helper. This ensures that the user isn't
+ * greeted with a black screen when e.g. X dies.
+ */
bool drm_fb_helper_restore_fbdev_mode(struct drm_fb_helper *fb_helper)
{
bool error = false;
int i, ret;
+
+ drm_warn_on_modeset_not_all_locked(fb_helper->dev);
+
for (i = 0; i < fb_helper->crtc_count; i++) {
struct drm_mode_set *mode_set = &fb_helper->crtc_info[i].mode_set;
ret = drm_mode_set_config_internal(mode_set);