From: Tom Murphy <murphyt7@tcd.ie>
To: Christoph Hellwig <hch@infradead.org>
Cc: intel-gfx@lists.freedesktop.org,
Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Jani Nikula <jani.nikula@linux.intel.com>,
iommu@lists.linux-foundation.org,
Rodrigo Vivi <rodrigo.vivi@intel.com>,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH V2 5/5] DO NOT MERGE: iommu: disable list appending in dma-iommu
Date: Mon, 7 Sep 2020 21:18:50 +0100 [thread overview]
Message-ID: <CALQxJute8_y=JsW4UV1awSccOjxT_1OyPdymq=R_PurVQzENeQ@mail.gmail.com> (raw)
In-Reply-To: <20200907070035.GA25114@infradead.org>
On Mon, 7 Sep 2020 at 08:00, Christoph Hellwig <hch@infradead.org> wrote:
>
> On Thu, Sep 03, 2020 at 09:18:37PM +0100, Tom Murphy wrote:
> > Disable combining sg segments in the dma-iommu api.
> > Combining the sg segments exposes a bug in the intel i915 driver which
> > causes visual artifacts and the screen to freeze. This is most likely
> > because of how the i915 handles the returned list. It probably doesn't
> > respect the returned value specifying the number of elements in the list
> > and instead depends on the previous behaviour of the intel iommu driver
> > which would return the same number of elements in the output list as in
> > the input list.
>
> So what is the state of addressing this properly in i915? IF we can't
I think this is the latest on addressing this issue:
https://patchwork.kernel.org/cover/11306999/
tl;dr: some people seem to be looking at it but I'm not sure if it's
being actively worked on
> get it done ASAP I wonder if we need a runtime quirk to disable
> merging instead of blocking this conversion..
Yeah we talked about passing an attr to map_sg to disable merging at
the following microconfernce:
https://linuxplumbersconf.org/event/7/contributions/846/
As far as I can remember everyone seemed happy with that solution. I
won't be working on this though as I don't have any more time to
dedicate to this. It seems Lu Baolu will take over this.
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next prev parent reply other threads:[~2020-09-07 20:19 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 20:18 [PATCH V2 0/5] Convert the intel iommu driver to the dma-iommu api Tom Murphy
2020-09-03 20:18 ` [PATCH V2 1/5] iommu: Handle freelists when using deferred flushing in iommu drivers Tom Murphy
2020-09-03 20:18 ` [PATCH V2 2/5] iommu: Add iommu_dma_free_cpu_cached_iovas function Tom Murphy
2020-09-09 0:45 ` Lu Baolu
2020-09-09 7:05 ` Christoph Hellwig
2020-09-12 2:55 ` Lu Baolu
2020-09-03 20:18 ` [PATCH V2 3/5] iommu: allow the dma-iommu api to use bounce buffers Tom Murphy
2020-09-09 1:34 ` Lu Baolu
2020-09-03 20:18 ` [PATCH V2 4/5] iommu/vt-d: Convert intel iommu driver to the iommu ops Tom Murphy
2020-09-09 1:59 ` Lu Baolu
2020-09-03 20:18 ` [PATCH V2 5/5] DO NOT MERGE: iommu: disable list appending in dma-iommu Tom Murphy
2020-09-07 7:00 ` Christoph Hellwig
2020-09-07 20:18 ` Tom Murphy [this message]
2020-09-08 5:36 ` Christoph Hellwig
2020-09-08 5:55 ` Christoph Hellwig
2020-09-08 6:04 ` Lu Baolu
2020-09-08 6:23 ` Christoph Hellwig
2020-09-08 9:07 ` Lu Baolu
2020-09-09 1:43 ` Lu Baolu
2020-09-09 7:06 ` Christoph Hellwig
2020-09-12 3:13 ` Lu Baolu
2020-09-04 10:03 ` [PATCH V2 0/5] Convert the intel iommu driver to the dma-iommu api Joerg Roedel
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