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

[Andi Shyti <andi.shyti@linux.intel.com>]

Hi Fei,

On Tue, Jun 06, 2023 at 12:00:42PM +0200, Andi Shyti wrote:
> From: Fei Yang <fei.yang@intel.com>
> 
> 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
> 
> The IGT test related to this change is
> igt@gem_create@create-ext-set-pat
> 
> Signed-off-by: Fei Yang <fei.yang@intel.com>
> Cc: Chris Wilson <chris.p.wilson@linux.intel.com>
> Cc: Matt Roper <matthew.d.roper@intel.com>
> Cc: Andi Shyti <andi.shyti@linux.intel.com>
> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
> Acked-by: Jordan Justen <jordan.l.justen@intel.com>
> Tested-by: Jordan Justen <jordan.l.justen@intel.com>
> Acked-by: Carl Zhang <carl.zhang@intel.com>
> Tested-by: Lihao Gu <lihao.gu@intel.com>
> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>

pushed to drm-intel-gt-next with:

 - Tvrtko's ack
 - Slawek's ack
 - the pull request link from media guys

Thank you!
Andi