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iommu/io-pgtable-arm: Support coherency for Mali LPAE

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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.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/8df778355378127ea7eccc9521d6427e3e48d4f2.1600780574.git.robin.murphy@arm.com
This commit is contained in:
Robin Murphy 2020-09-22 15:16:48 +01:00 committed by Neil Armstrong
parent fa3bfa3527
commit 728da60da7
1 changed files with 10 additions and 1 deletions
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11
drivers/iommu/io-pgtable-arm.c
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@ -440,7 +440,13 @@ static arm_lpae_iopte arm_lpae_prot_to_pte(struct arm_lpae_io_pgtable *data,
<< ARM_LPAE_PTE_ATTRINDX_SHIFT);
}
if (prot & IOMMU_CACHE)
/*
* Also Mali has its own notions of shareability wherein its Inner
* domain covers the cores within the GPU, and its Outer domain is
* "outside the GPU" (i.e. either the Inner or System domain in CPU
* terms, depending on coherency).
*/
if (prot & IOMMU_CACHE && data->iop.fmt != ARM_MALI_LPAE)
pte |= ARM_LPAE_PTE_SH_IS;
else
pte |= ARM_LPAE_PTE_SH_OS;
@ -1049,6 +1055,9 @@ arm_mali_lpae_alloc_pgtable(struct io_pgtable_cfg *cfg, void *cookie)
cfg->arm_mali_lpae_cfg.transtab = virt_to_phys(data->pgd) |
ARM_MALI_LPAE_TTBR_READ_INNER |
ARM_MALI_LPAE_TTBR_ADRMODE_TABLE;
if (cfg->coherent_walk)
cfg->arm_mali_lpae_cfg.transtab |= ARM_MALI_LPAE_TTBR_SHARE_OUTER;
return &data->iop;
out_free_data: