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SubjectRe: [PATCH v5 0/5] iommu: M1 Pro/Max DART support
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On 16/09/2022 18.41, 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.
>
> 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
>

For the whole series, modulo the trivial warning I mentioned:

Acked-by: Hector Martin <marcan@marcan.st>

Let's get this merged please, it's been blocking t6000 support for a
long time now :)

- Hector

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