On Fri, May 15, 2015 at 10:43:28AM +0100, Yong Wu wrote: > This patch adds support for mediatek m4u (MultiMedia Memory Management Unit). After looking at the page table code, I thought I'd come and check your TLB invalidate code here. > +static void mtk_iommu_tlb_flush_all(void *cookie) > +{ > + struct mtk_iommu_domain *domain = cookie; > + u32 val; > + > + val = F_INVLD_EN1 | F_INVLD_EN0; > + writel(val, domain->imuinfo->base + REG_MMU_INV_SEL); > + writel(F_ALL_INVLD, domain->imuinfo->base + REG_MMU_INVALIDATE); > +} > + > +static void mtk_iommu_tlb_add_flush(unsigned long iova, size_t size, > + bool leaf, void *cookie) > +{ > + struct mtk_iommu_domain *domain = cookie; > + void __iomem *m4u_base = domain->imuinfo->base; > + unsigned int iova_start = iova, iova_end = iova + size - 1; > + int ret; > + u32 val; > + > + val = F_INVLD_EN1 | F_INVLD_EN0; > + writel(val, m4u_base + REG_MMU_INV_SEL); > + > + writel(iova_start, m4u_base + REG_MMU_INVLD_START_A); > + writel(iova_end, m4u_base + REG_MMU_INVLD_END_A); > + writel(F_MMU_INV_RANGE, m4u_base + REG_MMU_INVALIDATE); > + > + ret = readl_poll_timeout_atomic(m4u_base + REG_MMU_CPE_DONE, val, > + val != 0, 10, 1000000); > + if (ret) { > + dev_warn(domain->imuinfo->dev, "Invalid tlb don't done\n"); > + mtk_iommu_tlb_flush_all(cookie); > + } > + writel(0, m4u_base + REG_MMU_CPE_DONE); > +} You don't need to wait for completion here if you can implement a proper ->tlb_sync callback. > +static void mtk_iommu_flush_pgtable(void *ptr, size_t size, void *cookie) > +{ > + /* > + * After delete arch_setup_dma_ops, > + * This will be replaced with dma_map_page > + */ > + __dma_flush_range(ptr, ptr + size); > +} This should give you the necessary barriers to ensure visibility of the updated page tables, so you can use the _relaxed io accessors for the other TLB functions. > +static struct iommu_gather_ops mtk_iommu_gather_ops = { > + .tlb_flush_all = mtk_iommu_tlb_flush_all, > + .tlb_add_flush = mtk_iommu_tlb_add_flush, > + .tlb_sync = mtk_iommu_tlb_flush_all, sync isn't required to flush anything; it's just supposed to wait for any outstanding invalidation (i.e. from tlb_add_flush) to complete. Will -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html