[Intel-gfx] [PATCH 7/7] drm/i915: Allow user to set cache at BO creation

[Yang, Fei]

> Subject: Re: [Intel-gfx] [PATCH 7/7] drm/i915: Allow user to set cache at BO creation
>
> On 01/04/2023 09:38, fei.yang at intel.com wrote:
>> From: Fei Yang <fei.yang at intel.com>
>>
>> To comply with the design that buffer objects shall have immutable
>> cache setting through out its 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.
>>
>> Cc: Chris Wilson <chris.p.wilson at linux.intel.com>
>> Cc: Matt Roper <matthew.d.roper at intel.com>
>> Signed-off-by: Fei Yang <fei.yang at intel.com>
>> Reviewed-by: Andi Shyti <andi.shyti at linux.intel.com>
>
>
> Just like the protected content uAPI, there is no way for userspace to tell
> this feature is available other than trying using it.
>
> Given the issues with protected content, is it not thing we could want to add?

Sorry I'm not aware of the issues with protected content, could you elaborate?
There was a long discussion on teams uAPI channel, could you comment there if
any concerns?

https://teams.microsoft.com/l/message/19:f1767bda6734476ba0a9c7d147b928d1@thread.skype/1675860924675?tenantId=46c98d88-e344-4ed4-8496-4ed7712e255d&groupId=379f3ae1-d138-4205-bb65-d4c7d38cb481&parentMessageId=1675860924675&teamName=GSE%20OSGC&channelName=i915%20uAPI%20changes&createdTime=1675860924675&allowXTenantAccess=false

Thanks,
-Fei

>Thanks,
>
>-Lionel
>
>
>> ---
>>   drivers/gpu/drm/i915/gem/i915_gem_create.c | 33 ++++++++++++++++++++
>>   include/uapi/drm/i915_drm.h                | 36 ++++++++++++++++++++++
>>   tools/include/uapi/drm/i915_drm.h          | 36 ++++++++++++++++++++++
>>   3 files changed, 105 insertions(+)
>>