From: "Christian König" <ckoenig.leichtzumerken@gmail.com>
To: l.stach@pengutronix.de, nicolas@ndufresne.ca,
ppaalanen@gmail.com, sumit.semwal@linaro.org, daniel@ffwll.ch,
robdclark@gmail.com, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org
Subject: Re: Try to address the DMA-buf coherency problem
Date: Thu, 27 Oct 2022 14:14:12 +0200 [thread overview]
Message-ID: <59ac9998-a838-abf8-124c-8fd98c4f0f7a@gmail.com> (raw)
In-Reply-To: <20221020121316.3946-1-christian.koenig@amd.com>
Am 20.10.22 um 14:13 schrieb Christian König:
> Hi guys,
>
> after finding that we essentially have two separate worlds for coherent sharing
> of buffer through DMA-buf I thought I will tackle that problem a bit and at
> least allow the framework to reject attachments which won't work.
>
> So those patches here add a new dma_coherent flag to each DMA-buf object
> telling the framework that dev_is_dma_coherent() needs to return true for an
> importing device to be able to attach. Since we should always have a fallback
> path this should give userspace the chance to still keep the use case working,
> either by doing a CPU copy instead or reversing the roles of exporter and
> importer.
>
> For DRM and most V4L2 devices I then fill in the dma_coherent flag based on the
> return value of dev_is_dma_coherent(). Exporting drivers are allowed to clear
> the flag for their buffers if special handling like the USWC flag in amdgpu or
> the uncached allocations for radeon/nouveau are in use.
>
> Additional to that importers can also check the flag if they have some
> non-snooping operations like the special scanout case for amdgpu for example.
>
> The patches are only smoke tested and the solution isn't ideal, but as far as
> I can see should at least keep things working.
Gentle ping on this. Lucas, Daniel and Nicolas you have been rather
active in the last discussion. Do you mind taking a look?
Thanks,
Christian.
>
> Please review and/or comment,
> Christian.
>
>
next prev parent reply other threads:[~2022-10-27 12:14 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-20 12:13 Try to address the DMA-buf coherency problem Christian König
2022-10-20 12:13 ` [PATCH 1/3] dma-buf: add dma_coherent flag Christian König
2022-10-20 12:13 ` [PATCH 2/3] drm/prime: set the dma_coherent flag for export Christian König
2022-10-20 14:43 ` Rob Clark
2022-10-20 14:56 ` Christian König
2022-10-28 1:11 ` Rob Clark
2022-10-20 12:13 ` [PATCH 3/3] media: videobuf2: set dma_coherent flag for DMA-buf Christian König
2022-11-04 10:42 ` Hans Verkuil
2022-10-27 12:14 ` Christian König [this message]
2022-10-28 8:09 ` Try to address the DMA-buf coherency problem Lucas Stach
2022-10-28 8:40 ` Christian König
2022-10-28 11:42 ` Lucas Stach
2022-10-28 14:26 ` Christian König
2022-10-28 15:46 ` Nicolas Dufresne
2022-10-28 17:50 ` Christian König
2022-10-28 18:47 ` Daniel Stone
2022-11-01 17:40 ` Christian König
2022-11-01 21:09 ` Nicolas Dufresne
2022-11-02 11:18 ` Christian König
2022-11-02 11:39 ` Lucas Stach
2022-11-02 12:21 ` Christian König
2022-11-02 17:10 ` Lucas Stach
2022-11-02 19:13 ` Christian König
2022-11-02 19:48 ` Lucas Stach
2022-11-17 9:35 ` Tomasz Figa
2022-11-17 12:10 ` Christian König
2022-11-17 15:38 ` Nicolas Dufresne
2022-11-18 19:32 ` Rob Clark
2022-11-19 20:35 ` Nicolas Dufresne
2022-11-22 14:36 ` Daniel Vetter
2022-11-22 17:33 ` Christian König
2022-11-22 18:26 ` Daniel Vetter
2022-11-23 8:33 ` Pekka Paalanen
2022-11-23 16:33 ` Daniel Vetter
2022-11-25 16:40 ` Nicolas Dufresne
2022-11-30 10:30 ` Daniel Vetter
2022-12-02 15:27 ` Christian König
2023-01-05 11:46 ` Daniel Vetter
2022-12-05 6:41 ` Tomasz Figa
2022-12-05 8:28 ` Christian König
2022-12-06 18:26 ` Nicolas Dufresne
2022-12-06 18:37 ` Christian König
2022-12-09 8:26 ` Tomasz Figa
2022-12-09 9:32 ` Pekka Paalanen
2022-12-09 17:07 ` Alex Deucher
2023-01-05 11:50 ` [Linaro-mm-sig] " Daniel Vetter
2022-12-12 3:13 ` Tomasz Figa
2022-12-09 10:27 ` Christian König
2022-12-12 3:00 ` Tomasz Figa
2022-12-12 11:15 ` Christian König
2023-01-05 20:39 ` Sebastian Wick
2022-11-04 14:58 ` Rob Clark
2022-11-04 15:00 ` Christian König
2022-11-02 12:19 ` Pekka Paalanen
2022-11-02 12:27 ` Christian König
2022-11-02 12:50 ` Pekka Paalanen
2022-11-02 12:56 ` Christian König
2022-11-03 22:16 ` Nicolas Dufresne
2022-11-04 9:03 ` Christian König
2022-11-04 13:38 ` Nicolas Dufresne
2022-11-04 14:51 ` Christian König
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=59ac9998-a838-abf8-124c-8fd98c4f0f7a@gmail.com \
--to=ckoenig.leichtzumerken@gmail.com \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=l.stach@pengutronix.de \
--cc=linaro-mm-sig@lists.linaro.org \
--cc=linux-media@vger.kernel.org \
--cc=nicolas@ndufresne.ca \
--cc=ppaalanen@gmail.com \
--cc=robdclark@gmail.com \
--cc=sumit.semwal@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).