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drm/fb-helper: Fix locking in drm_fb_helper_hotplug_event

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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>
This commit is contained in:
Daniel Vetter 2013-04-11 14:26:55 +00:00 committed by Dave Airlie
parent 1baee58638
commit 89ced12547
1 changed files with 5 additions and 3 deletions
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8
drivers/gpu/drm/drm_fb_helper.c
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@ -1544,10 +1544,10 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
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 @@ int drm_fb_helper_hotplug_event(struct drm_fb_helper *fb_helper)
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;