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

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);

drivers/gpu/drm/gma500/framebuffer.c

@@ -668,30 +668,6 @@ static void psb_user_framebuffer_destroy(struct drm_framebuffer *fb)
 {
 	struct psb_framebuffer *psbfb = to_psb_fb(fb);
 	struct gtt_range *r = psbfb->gtt;
-	struct drm_device *dev = fb->dev;
-	struct drm_psb_private *dev_priv = dev->dev_private;
-	struct psb_fbdev *fbdev = dev_priv->fbdev;
-	struct drm_crtc *crtc;
-	int reset = 0;
-
-	/* Should never get stolen memory for a user fb */
-	WARN_ON(r->stolen);
-
-	/* Check if we are erroneously live */
-	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
-		if (crtc->fb == fb)
-			reset = 1;
-
-	if (reset)
-		/*
-		 * Now force a sane response before we permit the DRM CRTC
-		 * layer to do stupid things like blank the display. Instead
-		 * we reset this framebuffer as if the user had forced a reset.
-		 * We must do this before the cleanup so that the DRM layer
-		 * doesn't get a chance to stick its oar in where it isn't
-		 * wanted.
-		 */
-		drm_fb_helper_restore_fbdev_mode(&fbdev->psb_fb_helper);
 
 	/* Let DRM do its clean up */
 	drm_framebuffer_cleanup(fb);

drivers/gpu/drm/gma500/psb_drv.c

@@ -149,6 +149,16 @@ static struct drm_ioctl_desc psb_ioctls[] = {
 
 static void psb_lastclose(struct drm_device *dev)
 {
+	int ret;
+	struct drm_psb_private *dev_priv = dev->dev_private;
+	struct psb_fbdev *fbdev = dev_priv->fbdev;
+
+	mutex_lock(&dev->mode_config.mutex);
+	ret = drm_fb_helper_restore_fbdev_mode(&fbdev->psb_fb_helper);
+	if (ret)
+		DRM_DEBUG("failed to restore crtc mode\n");
+	mutex_unlock(&dev->mode_config.mutex);
+
 	return;
 }