On Mon, Nov 28, 2016 at 03:15:12PM +0100, Daniel Vetter wrote:
> On Mon, Nov 28, 2016 at 08:46:11AM +0000, Chris Wilson wrote:
> > On Mon, Nov 28, 2016 at 08:48:34AM +0100, Daniel Vetter wrote:
> > > On Fri, Nov 25, 2016 at 03:32:31PM +0000, Chris Wilson wrote:
> > > > --- a/drivers/gpu/drm/drm_atomic.c
> > > > +++ b/drivers/gpu/drm/drm_atomic.c
> > > > @@ -1253,7 +1253,7 @@ drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,
> > > > DRM_DEBUG_ATOMIC("Set [NOFB] for plane state %p\n",
> > > > plane_state);
> > > >
> > > > - drm_framebuffer_assign(&plane_state->fb, fb);
> > > > + drm_framebuffer_assign(__mkwrite_drm_framebuffer(&plane_state->fb), fb);
> > >
> > > Feels like const gone the wrong way round? Or I'm not entirely clear on
> > > what this is supposed to achieve. Just dropping the const would still be a
> > > nice improvement.
> >
> > No one is supposed to be writing to it. Adding the const generates a
> > compiler warning for incorrect code that doesn't do the refcounting -
> > but doesn't generate a warning for anything simply checking the value.
> > It is the moral equivalent to calling it _fb to catch all the users.
>
> But then shouldn't all users use the drm_plane_set_fb helper (and that
> maybe gain a comment)? The above escaped the conversion/consolidation,
> which is why it looked funny to me ...
Yes, all users (of plane->fb = fb) are. The above is for
plane_state->fb.
I wasn't sure about adding comments to struct drm_plane, I thought the
crtc/fb there was just a crutch for !atomic.
But adding
+
+ /**
+ * @fb:
+ *
+ * Currently active framebuffer. Do not write this directly, use
+ * drm_plane_set_fb()
+ */
struct drm_framebuffer * const fb;
is not a hardship.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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