[PATCH] drm/atomic: Don't reject reflect-only rotations

[Daniel Vetter]

On Wed, Dec 07, 2016 at 01:32:57PM +0000, Chris Wilson wrote:
> On Wed, Dec 07, 2016 at 12:18:19PM +0000, Brian Starkey wrote:
> > The check to reject combinations of multiple rotation angles is overly
> > restrictive and has the side-effect of also failing any rotation value
> > which consists only of reflections.
> > 
> > Fix this by relaxing the check to ignore values which contain no
> > rotation flags.
> > 
> > Fixes: 6e0c7c3358d4 ("drm/atomic: Reject attempts to use multiple rotation angles at once")
> > Signed-off-by: Brian Starkey <brian.starkey at arm.com>
> 
> >  drivers/gpu/drm/drm_atomic.c |    3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> > index 362e3ea..44f4030 100644
> > --- a/drivers/gpu/drm/drm_atomic.c
> > +++ b/drivers/gpu/drm/drm_atomic.c
> > @@ -846,7 +846,8 @@ int drm_atomic_plane_set_property(struct drm_plane *plane,
> >  	} else if (property == config->prop_src_h) {
> >  		state->src_h = val;
> >  	} else if (property == plane->rotation_property) {
> > -		if (!is_power_of_2(val & DRM_ROTATE_MASK))
> > +		if ((val & DRM_ROTATE_MASK) &&
> 
> If val & DRM_ROTATE_MASK is zero, val must be REFLECT_X | REFLECT_Y.

While we bikeshed this check: Validation like this should be somewhere
behind ->atomic_check, since if it's only here then you can sneak invalid
stuff in through the legacy/compat set_property ioctls.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch