of_dma_configure() was *supposed* to be following the same logic as
acpi_dma_configure() and only setting bus_dma_mask if some range was
specified by the firmware. However, it seems that subtlety got lost in
the process of fitting it into the differently-shaped control flow, and
as a result the force_dma==true case ends up always setting the bus mask
to the 32-bit default, which is not what anyone wants.

Make sure we only touch it if the DT actually said so.

Fixes: 6c2fb2ea7636 ("of/device: Set bus DMA mask as appropriate")
Reported-by: Aaro Koskinen <aaro.koski...@iki.fi>
Reported-by: Jean-Philippe Brucker <jean-philippe.bruc...@arm.com>
Signed-off-by: Robin Murphy <robin.mur...@arm.com>
---

Sorry about that... I guess I only have test setups that either have
dma-ranges or where a 32-bit bus mask goes unnoticed :(

The Octeon and SMMU issues sound like they're purely down to this, and
it's probably related to at least one of John's Hikey woes.

Robin.

 drivers/of/device.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 0f27fad9fe94..757ae867674f 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -149,7 +149,8 @@ int of_dma_configure(struct device *dev, struct device_node 
*np, bool force_dma)
         * set by the driver.
         */
        mask = DMA_BIT_MASK(ilog2(dma_addr + size - 1) + 1);
-       dev->bus_dma_mask = mask;
+       if (!ret)
+               dev->bus_dma_mask = mask;
        dev->coherent_dma_mask &= mask;
        *dev->dma_mask &= mask;
 
-- 
2.19.1.dirty

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