From: Daniel Vetter <daniel@ffwll.ch>
To: Christoph Hellwig <hch@infradead.org>
Cc: Robin Murphy <robin.murphy@arm.com>,
Jonathan Marek <jonathan@marek.ca>,
David Airlie <airlied@linux.ie>,
freedreno@lists.freedesktop.org,
open list <linux-kernel@vger.kernel.org>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<dri-devel@lists.freedesktop.org>,
iommu@lists.linux-foundation.org, Daniel Vetter <daniel@ffwll.ch>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<linux-arm-msm@vger.kernel.org>, Sean Paul <sean@poorly.run>
Subject: Re: [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance
Date: Thu, 15 Oct 2020 17:33:34 +0200 [thread overview]
Message-ID: <20201015153334.GF438822@phenom.ffwll.local> (raw)
In-Reply-To: <20201015065532.GA15371@infradead.org>
On Thu, Oct 15, 2020 at 07:55:32AM +0100, Christoph Hellwig wrote:
> On Tue, Oct 13, 2020 at 02:42:38PM +0100, Robin Murphy wrote:
> > I still think this situation would be best handled with a variant of
> > dma_ops_bypass that also guarantees to bypass SWIOTLB, and can be set
> > automatically when attaching to an unmanaged IOMMU domain.
>
> dma_ops_bypass should mostly do the right thing as-is. swiotlb bouncing
> is triggered of two things:
>
> 1) the dma_mask. This is under control of the driver, and obviously
> if it is too small for a legit reason we can't just proceed
Somewhat related, but is there a way to tell the dma-api to fail instead
of falling back to swiotlb? In many case for gpu drivers it's much better
if we fall back to dma_alloc_coherent and manage the copying ourselves
instead of abstracting this away in the dma-api. Currently that's "solved"
rather pessimistically by always allocating from dma_alloc_coherent if
swiotlb could be in the picture (at least for ttm based drivers, i915 just
falls over).
-Daniel
> 2) force_dma_unencrypted() - we'd need to do an opt-out here, either
> by a flag or by being smart and looking for an attached iommu on
> the device
>
> > That way the
> > device driver can make DMA API calls in the appropriate places that do the
> > right thing either way, and only needs logic to decide whether to use the
> > returned DMA addresses directly or ignore them if it knows they're
> > overridden by its own IOMMU mapping.
>
> I'd be happy to review patches for this.
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
WARNING: multiple messages have this Message-ID (diff)
From: Daniel Vetter <daniel@ffwll.ch>
To: Christoph Hellwig <hch@infradead.org>
Cc: Sean Paul <sean@poorly.run>, Jonathan Marek <jonathan@marek.ca>,
David Airlie <airlied@linux.ie>,
Robin Murphy <robin.murphy@arm.com>,
open list <linux-kernel@vger.kernel.org>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<dri-devel@lists.freedesktop.org>,
iommu@lists.linux-foundation.org, Daniel Vetter <daniel@ffwll.ch>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<linux-arm-msm@vger.kernel.org>,
freedreno@lists.freedesktop.org
Subject: Re: [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance
Date: Thu, 15 Oct 2020 17:33:34 +0200 [thread overview]
Message-ID: <20201015153334.GF438822@phenom.ffwll.local> (raw)
In-Reply-To: <20201015065532.GA15371@infradead.org>
On Thu, Oct 15, 2020 at 07:55:32AM +0100, Christoph Hellwig wrote:
> On Tue, Oct 13, 2020 at 02:42:38PM +0100, Robin Murphy wrote:
> > I still think this situation would be best handled with a variant of
> > dma_ops_bypass that also guarantees to bypass SWIOTLB, and can be set
> > automatically when attaching to an unmanaged IOMMU domain.
>
> dma_ops_bypass should mostly do the right thing as-is. swiotlb bouncing
> is triggered of two things:
>
> 1) the dma_mask. This is under control of the driver, and obviously
> if it is too small for a legit reason we can't just proceed
Somewhat related, but is there a way to tell the dma-api to fail instead
of falling back to swiotlb? In many case for gpu drivers it's much better
if we fall back to dma_alloc_coherent and manage the copying ourselves
instead of abstracting this away in the dma-api. Currently that's "solved"
rather pessimistically by always allocating from dma_alloc_coherent if
swiotlb could be in the picture (at least for ttm based drivers, i915 just
falls over).
-Daniel
> 2) force_dma_unencrypted() - we'd need to do an opt-out here, either
> by a flag or by being smart and looking for an attached iommu on
> the device
>
> > That way the
> > device driver can make DMA API calls in the appropriate places that do the
> > right thing either way, and only needs logic to decide whether to use the
> > returned DMA addresses directly or ignore them if it knows they're
> > overridden by its own IOMMU mapping.
>
> I'd be happy to review patches for this.
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
WARNING: multiple messages have this Message-ID (diff)
From: Daniel Vetter <daniel@ffwll.ch>
To: Christoph Hellwig <hch@infradead.org>
Cc: Sean Paul <sean@poorly.run>, Jonathan Marek <jonathan@marek.ca>,
David Airlie <airlied@linux.ie>,
Robin Murphy <robin.murphy@arm.com>,
open list <linux-kernel@vger.kernel.org>,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<dri-devel@lists.freedesktop.org>,
iommu@lists.linux-foundation.org,
"open list:DRM DRIVER FOR MSM ADRENO GPU"
<linux-arm-msm@vger.kernel.org>,
freedreno@lists.freedesktop.org
Subject: Re: [PATCH 2/3] drm/msm: add DRM_MSM_GEM_SYNC_CACHE for non-coherent cache maintenance
Date: Thu, 15 Oct 2020 17:33:34 +0200 [thread overview]
Message-ID: <20201015153334.GF438822@phenom.ffwll.local> (raw)
In-Reply-To: <20201015065532.GA15371@infradead.org>
On Thu, Oct 15, 2020 at 07:55:32AM +0100, Christoph Hellwig wrote:
> On Tue, Oct 13, 2020 at 02:42:38PM +0100, Robin Murphy wrote:
> > I still think this situation would be best handled with a variant of
> > dma_ops_bypass that also guarantees to bypass SWIOTLB, and can be set
> > automatically when attaching to an unmanaged IOMMU domain.
>
> dma_ops_bypass should mostly do the right thing as-is. swiotlb bouncing
> is triggered of two things:
>
> 1) the dma_mask. This is under control of the driver, and obviously
> if it is too small for a legit reason we can't just proceed
Somewhat related, but is there a way to tell the dma-api to fail instead
of falling back to swiotlb? In many case for gpu drivers it's much better
if we fall back to dma_alloc_coherent and manage the copying ourselves
instead of abstracting this away in the dma-api. Currently that's "solved"
rather pessimistically by always allocating from dma_alloc_coherent if
swiotlb could be in the picture (at least for ttm based drivers, i915 just
falls over).
-Daniel
> 2) force_dma_unencrypted() - we'd need to do an opt-out here, either
> by a flag or by being smart and looking for an attached iommu on
> the device
>
> > That way the
> > device driver can make DMA API calls in the appropriate places that do the
> > right thing either way, and only needs logic to decide whether to use the
> > returned DMA addresses directly or ignore them if it knows they're
> > overridden by its own IOMMU mapping.
>
> I'd be happy to review patches for this.
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-10-15 15:33 UTC|newest]
Thread overview: 43+ 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 ` Jonathan Marek
2020-10-01 0:27 ` [PATCH 1/3] drm/msm: add MSM_BO_CACHED_COHERENT Jonathan Marek
2020-10-01 0:27 ` Jonathan Marek
2020-10-01 23:47 ` Jordan Crouse
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 0:27 ` Jonathan Marek
2020-10-01 23:29 ` [Freedreno] " Jordan Crouse
2020-10-01 23:29 ` Jordan Crouse
2020-10-02 7:53 ` Christoph Hellwig
2020-10-02 12:46 ` Jonathan Marek
2020-10-02 12:46 ` Jonathan Marek
2020-10-05 8:29 ` Christoph Hellwig
2020-10-05 14:35 ` Jonathan Marek
2020-10-05 14:35 ` Jonathan Marek
2020-10-06 7:23 ` Christoph Hellwig
2020-10-06 7:23 ` Christoph Hellwig
2020-10-06 13:19 ` Jonathan Marek
2020-10-06 13:19 ` Jonathan Marek
2020-10-06 13:19 ` Jonathan Marek
2020-10-07 6:25 ` Christoph Hellwig
2020-10-07 6:25 ` Christoph Hellwig
2020-10-13 13:42 ` Robin Murphy
2020-10-13 13:42 ` Robin Murphy
2020-10-13 13:42 ` Robin Murphy
2020-10-13 16:11 ` Rob Clark
2020-10-13 16:11 ` Rob Clark
2020-10-13 16:11 ` Rob Clark
2020-10-15 6:55 ` Christoph Hellwig
2020-10-15 6:55 ` Christoph Hellwig
2020-10-15 15:33 ` Daniel Vetter [this message]
2020-10-15 15:33 ` Daniel Vetter
2020-10-15 15:33 ` Daniel Vetter
2020-10-15 15:43 ` Christoph Hellwig
2020-10-15 15:43 ` Christoph Hellwig
2020-10-23 6:48 ` Christoph Hellwig
2020-10-23 6:48 ` Christoph Hellwig
2020-10-08 8:27 ` Joerg Roedel
2020-10-08 8:27 ` Joerg Roedel
2020-10-08 8:27 ` Joerg Roedel
2020-10-01 0:27 ` [PATCH 3/3] drm/msm: bump up the uapi version Jonathan Marek
2020-10-01 0:27 ` 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=20201015153334.GF438822@phenom.ffwll.local \
--to=daniel@ffwll.ch \
--cc=airlied@linux.ie \
--cc=dri-devel@lists.freedesktop.org \
--cc=freedreno@lists.freedesktop.org \
--cc=hch@infradead.org \
--cc=iommu@lists.linux-foundation.org \
--cc=jonathan@marek.ca \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=robin.murphy@arm.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.