[PATCH 05/12] drm/fb-helper: Drop locking from the vsync wait ioctl code

[Daniel Vetter]

Like with the drm-native vblank wait ioctl we can entirely rely on the
spinlocks in drm_vblank.c, no need at all to take expensive mutexes.
The only reason we had to take mode_config.mutex was to protect the
fbdev helper's data-structures, but that's now done by
fb_helper->lock.

Cc: John Stultz <john.stultz at linaro.org>
Cc: Thierry Reding <treding at nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 drivers/gpu/drm/drm_fb_helper.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 14b3f885a01f..13330c22e6bf 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1342,7 +1342,6 @@ int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
 		goto unlock;
 	}
 
-	mutex_lock(&dev->mode_config.mutex);
 	switch (cmd) {
 	case FBIO_WAITFORVSYNC:
 		/*
@@ -1382,7 +1381,6 @@ int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
 	}
 
 unlock:
-	mutex_unlock(&dev->mode_config.mutex);
 	mutex_unlock(&fb_helper->lock);
 	return ret;
 }
-- 
2.11.0