arm: dma-mapping: Don't override dma_ops in arch_setup_dma_ops()

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 overriden.

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: Sricharan R <sricharan@codeaurora.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Tested-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 63eabb06f9f1..ff131928be50 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2390,6 +2390,15 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
         const 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->dma_ops)
+                return;
+
         if (arm_setup_iommu_dma_ops(dev, dma_base, size, iommu))
                 dma_ops = arm_get_iommu_dma_map_ops(coherent);
         else