[PATCH/RFC] drm: Disallow DRM_IOCTL_MODESET_CTL for KMS drivers

[Laurent Pinchart]

DRM_IOCTL_MODESET_CTL must only be used for UMS drivers. Make it a no-op
for KMS drivers.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 drivers/gpu/drm/drm_irq.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

My understanding of the DRM framework tells me that calling
DRM_IOCTL_MODESET_CTL on a KMS driver is not only unneeded, but could also
mess up its internal state. Did I get it right ?

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index c798eea..03f16f3 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -974,7 +974,6 @@ EXPORT_SYMBOL(drm_vblank_off);
  * drm_vblank_pre_modeset - account for vblanks across mode sets
  * @dev: DRM device
  * @crtc: CRTC in question
- * @post: post or pre mode set?
  *
  * Account for vblank events across mode setting events, which will likely
  * reset the hardware frame counter.
@@ -1037,6 +1036,10 @@ int drm_modeset_ctl(struct drm_device *dev, void *data,
 	if (!dev->num_crtcs)
 		return 0;
 
+	/* KMS drivers handle this internally */
+	if (drm_core_check_feature(dev, DRIVER_MODESET))
+		return 0;
+
 	crtc = modeset->crtc;
 	if (crtc >= dev->num_crtcs)
 		return -EINVAL;
-- 
Regards,

Laurent Pinchart