[PATCH V3 1/8] arm: dma-mapping: Don't override dma_ops in arch_setup_dma_ops()

Sricharan R
2016-10-04T17:03:45Z

From: Laurent Pinchart <laurent.pinchart+renesas-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>

The arch_setup_dma_ops() function is in charge of setting dma_ops with a
call to set_dma_ops(). set_dma_ops() is also called from

- highbank and mvebu bus notifiers
- dmabounce (to be replaced with swiotlb)
- arm_iommu_attach_device

(arm_iommu_attach_device is itself called from IOMMU and bus master
device drivers)

To allow the arch_setup_dma_ops() call to be moved from device add time
to device probe time we must ensure that dma_ops already setup by any of
the above callers will not be overridden.

Aftering replacing dmabounce with swiotlb, converting IOMMU drivers to
of_xlate and taking care of highbank and mvebu, the workaround should be
removed.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
---
arch/arm/mm/dma-mapping.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index c6834c0..dde6514 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2322,6 +2322,15 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
struct dma_map_ops *dma_ops;

dev->archdata.dma_coherent = coherent;
+
+ /*
+ * Don't override the dma_ops if they have already been set. Ideally
+ * this should be the only location where dma_ops are set, remove this
+ * check when all other callers of set_dma_ops will have disappeared.
+ */
+ if (dev->archdata.dma_ops)
+ return;
+
if (arm_setup_iommu_dma_ops(dev, dma_base, size, iommu))
dma_ops = arm_get_iommu_dma_map_ops(coherent);
else
--
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