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Re: [PATCH 4/5] iommu/rockchip: add ARM64 cache flush operation for iommu

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On Tue, May 24, 2016 at 10:31:17AM +0800, Shunqian Zheng wrote:
> On 2016年05月23日 21:35, Catalin Marinas wrote:
> >On Mon, May 23, 2016 at 11:44:14AM +0100, Robin Murphy wrote:
> >>On 23/05/16 02:37, Shunqian Zheng wrote:
> >>>From: Simon <xxm@rock-chips.com>
> >>>
> >>>Signed-off-by: Simon <xxm@rock-chips.com>
> >>>---
> >>>  drivers/iommu/rockchip-iommu.c | 4 ++++
> >>>  1 file changed, 4 insertions(+)
> >>>
> >>>diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> >>>index 043d18c..1741b65 100644
> >>>--- a/drivers/iommu/rockchip-iommu.c
> >>>+++ b/drivers/iommu/rockchip-iommu.c
> >>>@@ -95,12 +95,16 @@ struct rk_iommu {
> >>>
> >>>  static inline void rk_table_flush(u32 *va, unsigned int count)
> >>>  {
> >>>+#if defined(CONFIG_ARM)
> >>>  	phys_addr_t pa_start = virt_to_phys(va);
> >>>  	phys_addr_t pa_end = virt_to_phys(va + count);
> >>>  	size_t size = pa_end - pa_start;
> >>>
> >>>  	__cpuc_flush_dcache_area(va, size);
> >>>  	outer_flush_range(pa_start, pa_end);
> >>>+#elif defined(CONFIG_ARM64)
> >>>+	__dma_flush_range(va, va + count);
> >>>+#endif
> >>Ugh, please don't use arch-private cache maintenance functions directly from
> >>a driver. Allocating/mapping page tables to be read by the IOMMU is still
> >>DMA, so using the DMA APIs is the correct way to manage them, *especially*
> >>if it needs to work across multiple architectures.
> 
> It's easier for us if changing  the __dma_flush_range() to
> __flush_dcache_area() is acceptable here?

It's not really acceptable for arm64, nor for arm32. Please fix this
driver in a similar way to commit e3c971960fd4 ("iommu/tegra-smmu:
Convert to use DMA API").

The only place where we allowed __flush_dcache_area() is in the GICv3
driver and that's because it hasn't been wired as a platform device
(yet).

-- 
Catalin

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[PATCH 0/5] iommu/rockchip: fix bugs; enable iommu for ARM64 Shunqian Zheng <zhengsq@rock-chips.com> - 2016-05-23 03:40 +0200
  [PATCH 5/5] iommu/rockchip: enable rockchip iommu on ARM64 platform Shunqian Zheng <zhengsq@rock-chips.com> - 2016-05-23 03:40 +0200
  [PATCH 2/5] iommu/rockchip: add map_sg callback for rk_iommu_ops Shunqian Zheng <zhengsq@rock-chips.com> - 2016-05-23 03:40 +0200
  [PATCH 3/5] iommu/rockchip: add sanity check for virtual device Shunqian Zheng <zhengsq@rock-chips.com> - 2016-05-23 03:40 +0200
  [PATCH 4/5] iommu/rockchip: add ARM64 cache flush operation for iommu Shunqian Zheng <zhengsq@rock-chips.com> - 2016-05-23 03:40 +0200
    Re: [PATCH 4/5] iommu/rockchip: add ARM64 cache flush operation for  iommu Robin Murphy <robin.murphy@arm.com> - 2016-05-23 12:50 +0200
      Re: [PATCH 4/5] iommu/rockchip: add ARM64 cache flush operation for  iommu Catalin Marinas <catalin.marinas@arm.com> - 2016-05-23 15:40 +0200
        Re: [PATCH 4/5] iommu/rockchip: add ARM64 cache flush operation for  iommu Shunqian Zheng <zhengsq@rock-chips.com> - 2016-05-24 04:40 +0200
          Re: [PATCH 4/5] iommu/rockchip: add ARM64 cache flush operation for  iommu Catalin Marinas <catalin.marinas@arm.com> - 2016-05-24 12:00 +0200

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