From: Robin Murphy robin.murphy@arm.com
commit 728da60da7c1ec1e21ae64648e376666de3c279c upstream.
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/8df778355378127ea7eccc9521d642... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iommu/io-pgtable-arm.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
--- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -417,7 +417,13 @@ static arm_lpae_iopte arm_lpae_prot_to_p << 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; @@ -1021,6 +1027,9 @@ arm_mali_lpae_alloc_pgtable(struct io_pg 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: