Re: [PATCH 2/2] iommu/io-pgtable-arm: use __dma_sync_single_for_device()

[Will Deacon]

On Sun, May 08, 2016 at 12:59:56PM +0200, Niklas Söderlund wrote:
> The call to dma_sync_single_for_device() can be reached from
> dma_map_single(). If CONFIG_DMA_API_DEBUG is enabled this would result
> in a check that the mapping being synced is valid. Since the call to
> dma_map_single is not yet completed the mapping is not recorded in
> dma-debug and the check fails and a warning is printed. Avoid this
> warning by calling __dma_sync_single_for_device() which don't preform
> this check.

Hmm, I don't understand why this would trigger that warning. The memory
being sync'd here is the page table memory, not the buffer being mapped.
The page table memory is "mapped" using dma_map_single in
__arm_lpae_alloc_pages, so it sounds like the issue something else.

Will

[PATCH 2/2] iommu/io-pgtable-arm: use __dma_sync_single_for_device()

[Niklas Söderlund]

The call to dma_sync_single_for_device() can be reached from
dma_map_single(). If CONFIG_DMA_API_DEBUG is enabled this would result
in a check that the mapping being synced is valid. Since the call to
dma_map_single is not yet completed the mapping is not recorded in
dma-debug and the check fails and a warning is printed. Avoid this
warning by calling __dma_sync_single_for_device() which don't preform
this check.

Signed-off-by: Niklas Söderlund 
---
 drivers/iommu/io-pgtable-arm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index f433b51..3da8102 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -255,7 +255,7 @@ static void __arm_lpae_set_pte(arm_lpae_iopte *ptep, 
arm_lpae_iopte pte,
*ptep = pte;
 
if (!selftest_running)
-   dma_sync_single_for_device(cfg->iommu_dev,
+   __dma_sync_single_for_device(cfg->iommu_dev,
   __arm_lpae_dma_addr(ptep),
   sizeof(pte), DMA_TO_DEVICE);
 }
-- 
2.8.2