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, 10 insertions, 0 deletions

diff --git a/drivers/gpu/drm/gma500/psb_drv.c b/drivers/gpu/drm/gma500/psb_drv.c
index dd1fbfa7e467..dbcefe9f78fa 100644
--- a/drivers/gpu/drm/gma500/psb_drv.c
+++ b/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;
 }