[Intel-gfx] [PATCH] RFC: drm: add support for tiled/compressed/etc modifier in addfb2

[Tvrtko Ursulin]

On 01/30/2015 01:43 PM, Rob Clark wrote:
> On Fri, Jan 30, 2015 at 5:51 AM, Tvrtko Ursulin
> <tvrtko.ursulin at linux.intel.com> wrote:
>>> +/*
>>> + * Format Modifier tokens:
>>> + *
>>> + * When adding a new token please document the layout with a code
>>> comment,
>>> + * similar to the fourcc codes above. drm_fourcc.h is considered the
>>> + * authoritative source for all of these.
>>> + */
>>
>>
>> On one side modifiers are supposed to be opaque, but then this suggest they
>> are supposed to be added in this file and described. Is that right?
>
>
> correct..   opaque as in basically enum values.
>
> We do want a description of the format so when someone comes along and
> adds a new value, we have a chance of realizing that it is the same as
> an existing value, since there are cases where gpu's from different
> vendors can support (for example) the same tiling formats.

Opaque kind of suggests it is driver private and from that angle 
definitions and descriptions wouldn't belong in the core uapi header. So 
I think that's just confusing and I'd drop opaque from the description 
and just call it a token.

(And another reason why I was suggesting to split the space for 
potential common and vendor/driver specific tokens.)

Regards,

Tvrtko