lkml.org 
[lkml]   [2022]   [Aug]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v8 2/2] drm/gem: Don't map imported GEMs
From
Am 16.08.22 um 13:44 schrieb Dmitry Osipenko:
> [SNIP]
>> The other complication I noticed is that we don't seem to keep around
>> the fd after importing to a GEM handle. And I could imagine that
>> doing so could cause issues with too many fd's. So I guess the best
>> thing is to keep the status quo and let drivers that cannot mmap
>> imported buffers just fail mmap?
> That actually should be all the drivers excluding those that use
> DRM-SHMEM because only DRM-SHMEM uses dma_buf_mmap(), that's why it
> works for Panfrost. I'm pretty sure mmaping of imported GEMs doesn't
> work for the MSM driver, isn't it?
>
> Intel and AMD drivers don't allow to map the imported dma-bufs. Both
> refuse to do the mapping.
>
> Although, AMDGPU "succeeds" to do the mapping using
> AMDGPU_GEM_DOMAIN_GTT, but then touching the mapping causes bus fault,
> hence mapping actually fails. I think it might be the AMDGPU
> driver/libdrm bug, haven't checked yet.

That's then certainly broken somehow. Amdgpu should nerve ever have
allowed to mmap() imported DMA-bufs and the last time I check it didn't.

Regards,
Christian.

>
> So we're back to the point that neither of DRM drivers need to map
> imported dma-bufs and this was never tested. In this case this patch is
> valid, IMO.
>

\
 
 \ /
  Last update: 2022-08-16 14:12    [W:0.153 / U:0.372 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site