[PATCH v8] drm: Add library for shmem backed GEM objects

anholt eric at anholt.net
Thu Mar 14 19:06:25 UTC 2019


Rob Herring <robh at kernel.org> writes:

> On Wed, Mar 13, 2019 at 3:56 PM Eric Anholt <eric at anholt.net> wrote:
>>
>> Rob Herring <robh at kernel.org> writes:
>>
>> > From: Noralf Trønnes <noralf at tronnes.org>
>> >
>> > This adds a library for shmem backed GEM objects.
>>
>> I read through the whole thing, and the only bit I didn't like
>> (drm_gem_shmem_create_with_handle returns an unrefcounted object
>> pointer) was a copy-and-paste from CMA that we should fix in both
>> places, and has no downside in the current usage since the pointer value
>> is unused.  Just one question left:
>>
>> > v7:
>> > - Use write-combine for mmap instead. This is the more common
>> >   case. (robher)
>>
>> I don't actually see this in the code.  Wasn't there supposed to be a:
>>
>>        vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
>
> That's the default if you trace drm_gem_mmap() -> drm_gem_mmap_obj().
> My wording here should have been more clear.

Ah, there it is!  Added review to the helpers, and I've pushed both
patches now.
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