[Intel-gfx] [PATCH] RFC: drm: add support for tiled/compressed/etc modifier in addfb2 (v1.5)

[Daniel Vetter]

On Wed, Jan 28, 2015 at 05:57:56PM +0000, Tvrtko Ursulin wrote:
> 
> On 01/28/2015 05:37 PM, Daniel Vetter wrote:
> >From: Rob Clark <robdclark at gmail.com>
> >
> >In DRM/KMS we are lacking a good way to deal with tiled/compressed
> >formats.  Especially in the case of dmabuf/prime buffer sharing, where
> >we cannot always rely on under-the-hood flags passed to driver specific
> >gem-create ioctl to pass around these extra flags.
> >
> >The proposal is to add a per-plane format modifier.  This allows to, if
> >necessary, use different tiling patters for sub-sampled planes, etc.
> >The format modifiers are added at the end of the ioctl struct, so for
> >legacy userspace it will be zero padded.
> >
> >TODO how best to deal with assignment of modifier token values?  The
> >rough idea was to namespace things with an 8bit vendor-id, and then
> >beyond that it is treated as an opaque value.  But that was a relatively
> >arbitrary choice.  There are cases where same tiling pattern and/or
> >compression is supported by various different vendors.  So we should
> >standardize to use the vendor-id and value of the first one who
> >documents the format?
> 
> Maybe:
> 	__u64 modifier[4];
> 	__u64 vendor_modifier[4];

Seems rendundant since the modifier added in this patch is already vendor
specific. Or what exactly are you trying to accomplish here?
-Daniel

> 
> ?
> 
> Regards,
> 
> Tvrtko

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch