[PATCH] iommu/rockchip: Remove redundant DMA syncs

[PATCH] iommu/rockchip: Remove redundant DMA syncs

[Robin Murphy]

When we allocate new pagetable pages, we don't modify them between the
initial dma_map_single() call and the dma_sync_single_for_device() call
via rk_iommu_flush(), so the latter is entirely pointless.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/iommu/rockchip-iommu.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index 7a2932772fdf..e5116d6a6260 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -682,7 +682,6 @@ static u32 *rk_dte_get_page_table(struct rk_iommu_domain *rk_domain,
 	dte = rk_mk_dte(pt_dma);
 	*dte_addr = dte;
 
-	rk_table_flush(rk_domain, pt_dma, NUM_PT_ENTRIES);
 	rk_table_flush(rk_domain,
 		       rk_domain->dt_dma + dte_index * sizeof(u32), 1);
 done:
@@ -1004,8 +1003,6 @@ static struct iommu_domain *rk_iommu_domain_alloc(unsigned type)
 		goto err_free_dt;
 	}
 
-	rk_table_flush(rk_domain, rk_domain->dt_dma, NUM_DT_ENTRIES);
-
 	spin_lock_init(&rk_domain->iommus_lock);
 	spin_lock_init(&rk_domain->dt_lock);
 	INIT_LIST_HEAD(&rk_domain->iommus);
-- 
2.21.0.dirty


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Re: [PATCH] iommu/rockchip: Remove redundant DMA syncs

[Joerg Roedel]

On Fri, May 21, 2021 at 02:49:39PM +0100, Robin Murphy wrote:
> When we allocate new pagetable pages, we don't modify them between the
> initial dma_map_single() call and the dma_sync_single_for_device() call
> via rk_iommu_flush(), so the latter is entirely pointless.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/iommu/rockchip-iommu.c | 3 ---
>  1 file changed, 3 deletions(-)

Applied, thanks Robin.

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