On 26/04/2023 16:41, Yang, Fei wrote:
> On 26/04/2023 07:24, fei.yang@xxxxxxxxx wrote:
>> From: Fei Yang <fei.yang@xxxxxxxxx>
>>
>> The first three patches in this series are taken from
>> https://patchwork.freedesktop.org/series/116868/
>> These patches are included here because the last patch
>> has dependency on the pat_index refactor.
>>
>> This series is focusing on uAPI changes,
>> 1. end support for set caching ioctl [PATCH 4/5]
>> 2. add set_pat extension for gem_create [PATCH 5/5]
>>
>> v2: drop one patch that was merged separately
>> 341ad0e8e254 drm/i915/mtl: Add PTE encode function
>
> Are the re-sends for stabilizing the series, or focusing on merge?
v2 was sent just to drop one of patches that has already been merged.
> If the latter then opens are:
>
> 1) Link to Mesa MR reviewed and ready to merge.
>
> 2) IGT reviewed.
>
> 3) I raised an open that get/set_caching should not "lie" but return an
> error if set pat extension has been used. I don't see a good reason not
> to do that.
I don't think it's "lying" to the userspace. the comparison is only valid
for objects created by KMD because only such object uses the pat_index
from the cachelevel_to_pat table.
Lets double check my understanding is correct. Userspace sequence of
operations:
1)
obj = gem_create()+set_pat(PAT_UC)
2a)
get_caching(obj)
What gets reported?
2b)
set_caching(obj, I915_CACHE_LLC)
What is the return code?
If answer to 2a is I915_CACHING_CACHED and to 2b) success, then please
state a good reason why both shouldn't return an error.
> + Joonas on this one.
>
> 4) Refactoring as done is not very pretty and I proposed an idea for a
> nicer approach. Feasible or not, open for discussion.
Still digesting your proposal. but not sure how would you define things
like PAT_UC as that is platform dependent, not a constant.
"PAT_UC" in my outline was purely a driver specific value, similarly as
I915_CACHE_... are. With the whole point that driver can ask if
something is uncached, WT or whatever. Using the platform specific
mapping table which converts platform specific obj->pat_index to driver
representation of caching modes (PAT_UC etc).
Quite possible I missed some detail, but if I haven't then it could be
a neat and lightweight solution.
Regards,
Tvrtko
