drm/fb-helper: Fix locking in drm_fb_helper_hotplug_event
Driver's and ->fill_modes functions are allowed to grab crtc mutexes
(for e.g. load detect). Hence we need to first only grab the general
kms mutex, and only in a second step grab all locks to do the
modesets.
This prevents a deadlock on my gm45 in the tv load detect code called
by drm_helper_probe_single_connector_modes.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 59d6b9b..892ff9f 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1544,10 +1544,10 @@
if (!fb_helper->fb)
return 0;
- drm_modeset_lock_all(dev);
+ mutex_lock(&fb_helper->dev->mode_config.mutex);
if (!drm_fb_helper_is_bound(fb_helper)) {
fb_helper->delayed_hotplug = true;
- drm_modeset_unlock_all(dev);
+ mutex_unlock(&fb_helper->dev->mode_config.mutex);
return 0;
}
DRM_DEBUG_KMS("\n");
@@ -1558,9 +1558,11 @@
count = drm_fb_helper_probe_connector_modes(fb_helper, max_width,
max_height);
+ mutex_unlock(&fb_helper->dev->mode_config.mutex);
+
+ drm_modeset_lock_all(dev);
drm_setup_crtcs(fb_helper);
drm_modeset_unlock_all(dev);
-
drm_fb_helper_set_par(fb_helper->fbdev);
return 0;
