From: Jordan Crouse <jcrouse@codeaurora.org>
To: Thierry Reding <thierry.reding@gmail.com>
Cc: devicetree@vger.kernel.org, David Airlie <airlied@linux.ie>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
Will Deacon <will.deacon@arm.com>,
Doug Anderson <dianders@chromium.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Linux IOMMU <iommu@lists.linux-foundation.org>,
Sean Paul <seanpaul@chromium.org>,
freedreno <freedreno@lists.freedesktop.org>,
Frank Rowand <frowand.list@gmail.com>,
Christoph Hellwig <hch@lst.de>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH] of/device: add blacklist for iommu dma_ops
Date: Mon, 3 Jun 2019 08:48:51 -0600 [thread overview]
Message-ID: <20190603144851.GD23227@jcrouse1-lnx.qualcomm.com> (raw)
In-Reply-To: <20190603144016.GG30132@ulmo>
> It shouldn't be a problem to hook something else up to the IOMMU
> subsystem. Hopefully it's something that people are going to standardize
> on.
>
> > 3) The automatic attach of DMA domain is also causing a different
> > problem for us on the GPU side, preventing us from supporting per-
> > context pagetables (since we end up with a disagreement about
> > which context bank is used between arm-smmu and the firmware).
>
> I'm not sure I understand this issue. Is the context bank hard-coded in
> the firmware somehow? Or is it possible to rewrite which one is going to
> be used at runtime? Do you switch out the actual page tables rather than
> the IOMMU domains for context switching?
We have a rather long history on this but the tl;dr is that the GPU microcode
switches the pagetables by rewriting TTBR0 on the fly (since this is
arm-smmu-v2 we have no better option) and yes, unfortunately it is hard coded
to use context bank 0. [1] is the current patchset to support all this,
including my own take on avoiding the dma-domain (all the cool kids have one).
Jordan
[1] https://patchwork.freedesktop.org/series/57441/
--
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project
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next prev parent reply other threads:[~2019-06-03 14:48 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-01 16:53 [PATCH] of/device: add blacklist for iommu dma_ops Rob Clark
2018-12-03 0:10 ` Tomasz Figa
[not found] ` <CAAFQd5CWRKGA2=TEpYvnLuBzu6=2h1i_YtmN_FusyFuLy5BpdQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-12-03 11:06 ` Marek Szyprowski
2018-12-03 12:45 ` Robin Murphy
[not found] ` <a29008a3-8eff-260d-5c93-9757a729f9e0-5wv7dgnIgG8@public.gmane.org>
2018-12-03 14:16 ` Rob Clark
2018-12-03 14:26 ` Rob Clark
[not found] ` <CAF6AEGvo0-oWNKcz6BEA8Eh250FL4rXaBVYXuJGBtshPk4jz+g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-12-04 6:34 ` Vivek Gautam
[not found] ` <20181201165348.24140-1-robdclark-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-12-04 22:29 ` Rob Herring
2019-05-10 14:35 ` Rob Clark
2019-06-02 19:08 ` Rob Clark
2019-06-03 6:20 ` Tomasz Figa
2019-06-03 7:56 ` Vivek Gautam
2019-06-03 10:44 ` Rob Clark
2019-06-03 11:12 ` Vivek Gautam
2019-06-03 11:17 ` Christoph Hellwig
2019-06-03 11:32 ` Vivek Gautam
2019-06-03 10:47 ` Rob Clark
2019-06-03 11:14 ` Robin Murphy
2019-06-03 13:20 ` Rob Clark
2019-06-03 13:54 ` Thierry Reding
2019-06-03 14:20 ` Rob Clark
2019-06-03 14:40 ` Thierry Reding
2019-06-03 14:48 ` Jordan Crouse [this message]
2019-06-03 13:39 ` Thierry Reding
2019-06-05 6:57 ` Tomasz Figa
2019-06-05 12:57 ` [Freedreno] " Rob Clark
2019-06-05 13:18 ` Marek Szyprowski
2019-06-05 14:16 ` Rob Clark
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