From: Robin Murphy <robin.murphy@arm.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: Konrad Dybcio <konrad.dybcio@somainline.org>,
asahi@lists.linux.dev, Alyssa Rosenzweig <alyssa@rosenzweig.io>,
Hector Martin <marcan@marcan.st>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Mark Kettenis <mark.kettenis@xs4all.nl>,
Rob Herring <robh+dt@kernel.org>, Sven Peter <sven@svenpeter.dev>,
Will Deacon <will@kernel.org>,
devicetree@vger.kernel.org, iommu@lists.linux-foundation.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, iommu@lists.linux.dev,
Janne Grunau <j@jannau.net>
Subject: Re: [PATCH v5 0/5] iommu: M1 Pro/Max DART support
Date: Wed, 21 Sep 2022 14:20:40 +0100 [thread overview]
Message-ID: <11708ed1-b74a-5d45-0ce3-e2649dac1e8a@arm.com> (raw)
In-Reply-To: <20220916094152.87137-1-j@jannau.net>
On 2022-09-16 10:41, Janne Grunau wrote:
> Hej,
>
> this is the next attempt adding support for the DART found in Apple's
> M1 Pro/Max/Ultra. This adds a separate io-pgtable implementation for
> DART. As already mentioned in v2 the pte format is not fully compatible
> with io-pgtable-arm. Especially the 2nd least significant bit is used
> and is not available to tag tables/pages.
> io-pgtable-dart.c is copied from io-pgtable-arm.c and support for
> unused features is removed. Support for 4k IO pages is left for A7 to
> A11 SoCs as there's work underway to run Linux on them.
>
> The incompatibilities between both Apple DART pte seems manageable in
> their own io-pgtable implementation. A short list of the known
> differences:
>
> - the physical addresses are shifted left by 4 bits and and have 2 more
> bits inside the PTE entries
> - the read/write protection flags are at a different position
> - the subpage protection feature is now mandatory. For Linux we can
> just configure it to always allow access to the entire page.
> - BIT(1) tags "uncached" mappings (used for the display controller)
>
> There is second type of DART (t8110) present on M1 Pro/Max SoCs which
> uses the same PTE format as t6000.
FWIW I think there's minimal risk in queueing this up as a late addition
for 6.1, lest it get forgotten again. I've not been following it since
I've been busy with other things and I largely trust that DART patches
are well-tested, but from a quick skim it all earns a solid "yeah, why
not" from me :)
Cheers,
Robin.
> Changes in v5:
> - collected Sven's ack
> - minor fixes in "iommu/io-pgtable: Move Apple DART support to its own
> file"
>
> Changes in v4:
> - split dart and io-pgtable-dart build to allow building dart as module
> - add missing "SELECT IOMMU_IO_PGTABLE"
> - made map/unmap_pages/iova_to_phys inon-recursive
> - replace pgd concatenation with multiple table handling
> - simplified config and page size checks
> - collected Robin's Ack
>
> Changes in v3:
> - move APPLE_DART to its own io-pgtable implementation, copied from
> io-pgtable-arm and simplified
>
> Changes in v2:
> - added Rob's Acked-by:
> - add APPLE_DART2 io-pgtable format
>
> Janne Grunau (1):
> iommu/io-pgtable: Move Apple DART support to its own file
>
> Sven Peter (4):
> dt-bindings: iommu: dart: add t6000 compatible
> iommu/io-pgtable: Add DART subpage protection support
> iommu/io-pgtable-dart: Add DART PTE support for t6000
> iommu: dart: Support t6000 variant
>
> .../devicetree/bindings/iommu/apple,dart.yaml | 4 +-
> MAINTAINERS | 1 +
> drivers/iommu/Kconfig | 13 +-
> drivers/iommu/Makefile | 1 +
> drivers/iommu/apple-dart.c | 24 +-
> drivers/iommu/io-pgtable-arm.c | 63 ---
> drivers/iommu/io-pgtable-dart.c | 470 ++++++++++++++++++
> drivers/iommu/io-pgtable.c | 3 +
> include/linux/io-pgtable.h | 1 +
> 9 files changed, 512 insertions(+), 68 deletions(-)
> create mode 100644 drivers/iommu/io-pgtable-dart.c
>
next prev parent reply other threads:[~2022-09-21 13:20 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 9:41 [PATCH v5 0/5] iommu: M1 Pro/Max DART support Janne Grunau
2022-09-16 9:41 ` [PATCH v5 1/5] dt-bindings: iommu: dart: add t6000 compatible Janne Grunau
2022-09-22 12:05 ` Hector Martin
2022-09-16 9:41 ` [PATCH v5 2/5] iommu/io-pgtable: Move Apple DART support to its own file Janne Grunau
2022-09-22 14:05 ` Hector Martin
2022-09-16 9:41 ` [PATCH v5 3/5] iommu/io-pgtable: Add DART subpage protection support Janne Grunau
2022-09-16 11:57 ` Rob Herring
2022-09-16 9:41 ` [PATCH v5 4/5] iommu/io-pgtable-dart: Add DART PTE support for t6000 Janne Grunau
2022-09-16 12:03 ` Rob Herring
2022-09-16 9:41 ` [PATCH v5 5/5] iommu: dart: Support t6000 variant Janne Grunau
2022-09-16 12:05 ` Rob Herring
2022-09-21 13:20 ` Robin Murphy [this message]
2022-09-22 14:05 ` [PATCH v5 0/5] iommu: M1 Pro/Max DART support Hector Martin
2022-09-26 11:50 ` Joerg Roedel
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