[RFC PATCH 15/15] iommu/exynos: update to use iommu big-endian
From: m.szyprowski@samsung.com (Marek Szyprowski)
Date: 2016-06-09 06:51:25
Also in:
linux-iommu, linux-samsung-soc, lkml
Hi On 2016-06-08 20:31, Matthew Leach wrote:
From: Ben Dooks <redacted> Add initial support for big endian by always writing the pte in le32. Note, revisit if hardware capable of doing big endian fetches. Signed-off-by: Ben Dooks <redacted>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com> Just to keep my curiosity satisfied - what's the reason to use big-endian on ARM? Good luck with fixing the kernel and userspace codes, which usually assume little-endian is the only possible order!
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--- Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Kukjin Kim <kgene@kernel.org> Cc: Krzysztof Kozlowski <redacted> Cc: iommu at lists.linux-foundation.org Cc: linux-arm-kernel at lists.infradead.org Cc: linux-samsung-soc at vger.kernel.org Cc: linux-kernel at vger.kernel.org (open list) --- drivers/iommu/exynos-iommu.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c index 5ecc86c..dd8b3b3 100644 --- a/drivers/iommu/exynos-iommu.c +++ b/drivers/iommu/exynos-iommu.c@@ -54,6 +54,10 @@ typedef u32 sysmmu_pte_t; #define lv2ent_small(pent) ((*(pent) & 2) == 2) #define lv2ent_large(pent) ((*(pent) & 3) == 1) +#ifdef CONFIG_BIG_ENDIAN +#warning "revisit driver if we can enable big-endian ptes" +#endif +
This warning can be removed. There is no way to force SYSMMU to operate with big-endian PTEs according to the datasheet.
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/* * v1.x - v3.x SYSMMU supports 32bit physical and 32bit virtual address spaces * v5.0 introduced support for 36bit physical address space by shifting@@ -716,7 +720,7 @@ static inline void update_pte(sysmmu_pte_t *ent, sysmmu_pte_t val) { dma_sync_single_for_cpu(dma_dev, virt_to_phys(ent), sizeof(*ent), DMA_TO_DEVICE); - *ent = val; + *ent = cpu_to_le32(val); dma_sync_single_for_device(dma_dev, virt_to_phys(ent), sizeof(*ent), DMA_TO_DEVICE); }
Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland