The xhci platform driver needs to work on systems that either only
support 64-bit DMA or only support 32-bit DMA. Attempt to set a
coherent dma mask for 64-bit DMA, and attempt again with 32-bit
DMA if that fails.

Signed-off-by: Mark Langsdorf <[email protected]>
---
 drivers/usb/host/xhci-plat.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 1a0cf9f..3045e77 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -147,14 +147,17 @@ static int xhci_plat_probe(struct platform_device *pdev)
                        return ret;
        }
 
-       /* Initialize dma_mask and coherent_dma_mask to 32-bits */
-       ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
-       if (ret)
-               return ret;
+       /* Try setting the coherent_dma_mask to 64 bits, then try 32 bits */
+       if (sizeof(dma_addr_t) < 8 ||
+               dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64))) {
+               ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
+               if (ret)
+                       return ret;
+       }
        if (!pdev->dev.dma_mask)
                pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
        else
-               dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
+               dma_set_mask(&pdev->dev, pdev->dev.coherent_dma_mask);
 
        hcd = usb_create_hcd(driver, &pdev->dev, dev_name(&pdev->dev));
        if (!hcd)
-- 
1.9.3

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