From: Christoph Hellwig <hch@infradead.org>
To: Jonathan Marek <jonathan@marek.ca>
Cc: Christoph Hellwig <hch@infradead.org>,
freedreno@lists.freedesktop.org, Rob Clark <robdclark@gmail.com>,
Sean Paul <sean@poorly.run>, David Airlie <airlied@linux.ie>,
Daniel Vetter <daniel@ffwll.ch>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<linux-arm-msm@vger.kernel.org>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<dri-devel@lists.freedesktop.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance
Date: Mon, 5 Oct 2020 09:29:14 +0100 [thread overview]
Message-ID: <20201005082914.GA31702@infradead.org> (raw)
In-Reply-To: <b22fb797-67b0-a912-1d23-2b47c9a9e674@marek.ca>
On Fri, Oct 02, 2020 at 08:46:35AM -0400, Jonathan Marek wrote:
> > > +void msm_gem_sync_cache(struct drm_gem_object *obj, uint32_t flags,
> > > + size_t range_start, size_t range_end)
> > > +{
> > > + struct msm_gem_object *msm_obj = to_msm_bo(obj);
> > > +
> > > + /* TODO: sync only the required range, and don't invalidate on clean */
> > > +
> > > + if (flags & MSM_GEM_SYNC_CACHE_CLEAN)
> > > + sync_for_device(msm_obj);
> > > +
> > > + if (flags & MSM_GEM_SYNC_CACHE_INVALIDATE)
> > > + sync_for_cpu(msm_obj);
> >
> > And make to these ones as well. They are complete abuses of the DMA
> > API, and while we had to live with that for now to not cause regressions
> > they absoutely must not be exposed in a userspace ABI like this.
> >
>
> How do you propose that cached non-coherent memory be implemented? It is a
> useful feature for userspace.
If the driver is using the DMA API you need to use dma_alloc_noncoherent
and friends as of 5.10 (see the iommu list for the discussion).
If you use the raw IOMMU API (which I think the msm drm driver does) you
need to work with the maintainers to implement a cache synchronization
API that is not tied to the DMA API.
next prev parent reply other threads:[~2020-10-05 8:29 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 0:27 [PATCH 0/3] drm/msm: support for host-cached BOs Jonathan Marek
2020-10-01 0:27 ` [PATCH 1/3] drm/msm: add MSM_BO_CACHED_COHERENT Jonathan Marek
2020-10-01 23:47 ` Jordan Crouse
2020-10-01 0:27 ` [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance Jonathan Marek
2020-10-01 23:29 ` [Freedreno] " Jordan Crouse
2020-10-02 7:53 ` Christoph Hellwig
2020-10-02 12:46 ` Jonathan Marek
2020-10-05 8:29 ` Christoph Hellwig [this message]
2020-10-05 14:35 ` Jonathan Marek
2020-10-06 7:23 ` Christoph Hellwig
2020-10-06 13:19 ` Jonathan Marek
2020-10-07 6:25 ` Christoph Hellwig
2020-10-13 13:42 ` Robin Murphy
2020-10-13 16:11 ` Rob Clark
2020-10-15 6:55 ` Christoph Hellwig
2020-10-15 15:33 ` Daniel Vetter
2020-10-15 15:43 ` Christoph Hellwig
2020-10-23 6:48 ` Christoph Hellwig
2020-10-08 8:27 ` Joerg Roedel
2020-10-01 0:27 ` [PATCH 3/3] drm/msm: bump up the uapi version Jonathan Marek
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=20201005082914.GA31702@infradead.org \
--to=hch@infradead.org \
--cc=airlied@linux.ie \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=freedreno@lists.freedesktop.org \
--cc=jonathan@marek.ca \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=robdclark@gmail.com \
--cc=sean@poorly.run \
/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).