[Intel-gfx] [PATCH v17 1/1] drm/i915: Allow user to set cache at BO creation

[Andi Shyti]

> > > > To comply with the design that buffer objects shall have immutable
> > > > cache setting through out their life cycle, {set, get}_caching ioctl's
> > > > are no longer supported from MTL onward. With that change caching
> > > > policy can only be set at object creation time. The current code
> > > > applies a default (platform dependent) cache setting for all objects.
> > > > However this is not optimal for performance tuning. The patch extends
> > > > the existing gem_create uAPI to let user set PAT index for the object
> > > > at creation time.
> > > > The new extension is platform independent, so UMD's can switch to using
> > > > this extension for older platforms as well, while {set, get}_caching are
> > > > still supported on these legacy paltforms for compatibility reason.
> > > > However, since PAT index was not clearly defined for platforms prior to
> > > > GEN12 (TGL), so we are limiting this externsion to GEN12+ platforms
> > > > only. See ext_set_pat() in for the implementation details.
> > > > 
> > > > Note: The documentation related to the PAT/MOCS tables is currently
> > > > available for Tiger Lake here:
> > > > https://www.intel.com/content/www/us/en/docs/graphics-for-linux/developer-reference/1-0/tiger-lake.html
> > > > 
> > > > BSpec: 45101
> > > > 
> > > > Mesa support has been submitted in this merge request:
> > > > https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22878
> > > > 
> > > > The media driver is supported by the following commits:
> > > > https://github.com/intel/media-driver/commit/92c00a857433ebb34ec575e9834f473c6fcb6341
> > > > https://github.com/intel/media-driver/commit/fd375cf2c5e1f6bf6b43258ff797b3134aadc9fd
> > > > https://github.com/intel/media-driver/commit/08dd244b22484770a33464c2c8ae85430e548000
> 
> Andi, let's still get these corrected before merging once the media-driver
> revert is completed.

Sure!

At least this doesn't need a new version to be respinned.

Please, Carl, link the new pull request and I will update the
commit log.

Andi