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

[Zhang, Carl]

Media driver reverted previous patches, and file a new  PR
https://github.com/intel/media-driver/pull/1680
will hold this PR until the uapi changes appear in drm_next.

besides this, ask a dumb question. 
How we retrieve the pat_index from a shared resource though dma_buf fd?
maybe we need to know whether it could be CPU cached if we want map it.
Of course, looks there are no real usage to access it though CPU. 
Just use it directly without any pat related options ?

Thanks
Carl

> -----Original Message-----
> From: Andi Shyti <andi.shyti at linux.intel.com>
> Sent: Tuesday, June 6, 2023 7:15 PM
> To: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Andi Shyti <andi.shyti at linux.intel.com>; Tvrtko Ursulin
> <tvrtko.ursulin at linux.intel.com>; Yang, Fei <fei.yang at intel.com>; Chris
> Wilson <chris at chris-wilson.co.uk>; Roper, Matthew D
> <matthew.d.roper at intel.com>; Justen, Jordan L <jordan.l.justen at intel.com>;
> Zhang, Carl <carl.zhang at intel.com>; Gu, Lihao <lihao.gu at intel.com>; Intel
> GFX <intel-gfx at lists.freedesktop.org>; DRI Devel <dri-
> devel at lists.freedesktop.org>
> Subject: Re: [PATCH v17 1/1] drm/i915: Allow user to set cache at BO creation
> 
> > > > > 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/92c00a857433ebb34ec
> > > > > 575e9834f473c6fcb6341
> > > > > https://github.com/intel/media-driver/commit/fd375cf2c5e1f6bf6b4
> > > > > 3258ff797b3134aadc9fd
> > > > > https://github.com/intel/media-
> driver/commit/08dd244b22484770a33
> > > > > 464c2c8ae85430e548000
> >
> > 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