From b3880b955190fbf211fbd3f1c4d576a6ab297c67 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Tue, 22 Sep 2020 15:16:48 +0100 Subject: [PATCH] iommu/io-pgtable-arm: Support coherency for Mali LPAE 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 Tested-by: Neil Armstrong Reviewed-by: Steven Price Acked-by: Will Deacon Signed-off-by: Neil Armstrong Link: https://patchwork.freedesktop.org/patch/msgid/8df778355378127ea7eccc9521d6427e3e48d4f2.1600780574.git.robin.murphy@arm.com --- drivers/iommu/io-pgtable-arm.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index dc7bcf858b6d2..b4072a18e45dc 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -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: -- 2.39.5