[Intel-gfx] [PATCH 1/3] drm: Add new DRM_IOCTL_MODE_GETPLANE2

[Ville Syrjälä]

On Wed, Jan 11, 2017 at 08:43:16PM -0500, Rob Clark wrote:
> On Wed, Jan 11, 2017 at 7:51 PM, Ben Widawsky <ben at bwidawsk.net> wrote:
> >
> > +struct drm_format_modifier {
> > +       /* Bitmask of formats in get_plane format list this info
> > +        * applies to. */
> > +       uint64_t formats;
> 
> re: the uabi, I'd suggest to at least make this 'u32 offset; u32
> formats'.. we can keep the existing implementation in this patch and
> always set 'offset' to zero, and let the first one to hit more than 32
> formats deal with the implementation.  (Maybe a strategically placed
> WARN_ON() if you go that route..)

Isn't an implicit offset enough? As in first mask for a specific
modifier is for format indexes 0-63, second mask for the same modifier
is for 64-127, and so on.

The bigger issue is the userspace side I think. If we don't add the
userspace side code to handle this case from the get go, it's going to
be hard to actually start doing it from the kernel side.

> 
> Otherwise I guess it is just a couple years until getplane3 ;-)
> 
> BR,
> -R
> 
> > +
> > +       /* This modifier can be used with the format for this plane. */
> > +       uint64_t modifier;
> > +};
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-- 
Ville Syrjälä
Intel OTC