On Tue, 22 Sep 2020 15:16:48 +0100 Robin Murphy <robin.murphy@xxxxxxx> wrote: > 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. > > Reviewed-by: Steven Price <steven.price@xxxxxxx> > Tested-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx> > Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx> > --- > 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 dc7bcf858b6d..b4072a18e45d 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; Actually, it still doesn't work on s922x :-/. For it to work I correctly, I need to drop the outer shareable flag here. > @@ -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: _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
