drm/gma500: move fbcon restore to lastclose

Doing this within the fb->destroy callback leads to a locking
nightmare. And all other drm drivers that restore the fbcon do
it in lastclose, too.

With this adjustments all fb->destroy callbacks optionally drop
references to any gem objects used as backing storage, call
drm_framebuffer_cleanup and then kfree the struct. Which nicely
simplifies the locking for framebuffer unreferencing and freeing,
since this doesn't require that we hold the mode_config lock. A
slight exception is the vmwgfx surface backed framebuffer, it also
calls drm_master_put and removes the object from a device-private
framebuffer list. Both seem to have solid locking in place already.

Conclusion is that now it is no longer required to hold the
mode_config lock while freeing a framebuffer.

v2: Drop the corresponding mutex_lock WARN check from
drm_framebuffer_unreference.

v3: Use just the mode_config lock not modeset_lock_all, due to patch
reordering.

Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 0 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 81545540b2df..8d665fafc15e 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -317,9 +317,7 @@ static void drm_framebuffer_free(struct kref *kref)
  */
 void drm_framebuffer_unreference(struct drm_framebuffer *fb)
 {
-	struct drm_device *dev = fb->dev;
 	DRM_DEBUG("FB ID: %d\n", fb->base.id);
-	WARN_ON(!drm_modeset_is_locked(dev));
 	kref_put(&fb->refcount, drm_framebuffer_free);
 }
 EXPORT_SYMBOL(drm_framebuffer_unreference);