From: Rob Herring <robh@kernel.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>,
Neil Armstrong <narmstrong@baylibre.com>,
Joerg Roedel <joro@8bytes.org>,
Steven Price <steven.price@arm.com>,
Linux IOMMU <iommu@lists.linux-foundation.org>,
Will Deacon <will@kernel.org>,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 3/3] iommu/io-pgtable-arm: Allow coherent walks for Mali
Date: Mon, 30 Sep 2019 13:36:32 -0500 [thread overview]
Message-ID: <CAL_JsqJD0DKZkDAOsAcJPM24opvRqKHB3jsHqjeyjQM2WV9BEw@mail.gmail.com> (raw)
In-Reply-To: <fd1f7700165b2e2679fe6d499ec38b91f4a432f4.1569851517.git.robin.murphy@arm.com>
On Mon, Sep 30, 2019 at 9:11 AM Robin Murphy <robin.murphy@arm.com> wrote:
>
> Midgard GPUs have ACE-Lite master interfaces which allows systems to
> integrate them in an I/O-coherent manner. It seems that from the GPU's
> viewpoint, the rest of the system is its outer shareable domain, and so
> even when snoop signals are wired up, they are only emitted for outer
> shareable accesses. As such, setting the TTBR_SHARE_OUTER bit does
> indeed get coherent pagetable walks working nicely for the coherent
> T620 in the Arm Juno SoC.
>
> Exploiting coherency for data accesses is more of a challenge, since
> not only do we need to get the GPU MMU attributes right but we'd also
> have to avoid pgprot_writecombine creating an attribute mismatch on
> the CPU side, so we won't try wiring that up just yet.
>
> Reviewed-by: Steven Price <steven.price@arm.com>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
> drivers/iommu/io-pgtable-arm.c | 3 +++
> 1 file changed, 3 insertions(+)
Reviewed-by: Rob Herring <robh@kernel.org>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
prev parent reply other threads:[~2019-09-30 18:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-30 14:10 [PATCH v2 0/3] iommu/io-pgtable-arm: Mali LPAE improvements Robin Murphy
2019-09-30 14:11 ` [PATCH v2 1/3] iommu/io-pgtable-arm: Correct Mali attributes Robin Murphy
2019-09-30 18:35 ` Rob Herring
2019-09-30 14:11 ` [PATCH v2 2/3] iommu/io-pgtable-arm: Support all Mali configurations Robin Murphy
2019-09-30 18:36 ` Rob Herring
2019-09-30 14:11 ` [PATCH v2 3/3] iommu/io-pgtable-arm: Allow coherent walks for Mali Robin Murphy
2019-09-30 18:36 ` Rob Herring [this message]
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=CAL_JsqJD0DKZkDAOsAcJPM24opvRqKHB3jsHqjeyjQM2WV9BEw@mail.gmail.com \
--to=robh@kernel.org \
--cc=iommu@lists.linux-foundation.org \
--cc=joro@8bytes.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=narmstrong@baylibre.com \
--cc=robin.murphy@arm.com \
--cc=steven.price@arm.com \
--cc=tomeu.vizoso@collabora.com \
--cc=will@kernel.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).