usb: make xhci platform driver use 64 bit or 32 bit DMA

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.

[dhdang: regenerate the patch over v4.3-rc1 and address new comments]
Signed-off-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Duc Dang <dhdang@apm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 890ad9d9d32991c7e74b02d9580b5cfbcd4d595e..34c93e87b2d3881f5ea2ac7a8937038f75972e2e 100644 (file)
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -93,14 +93,20 @@ static int xhci_plat_probe(struct platform_device *pdev)
        if (irq < 0)
                return -ENODEV;
 
-       /* 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;
-       if (!pdev->dev.dma_mask)
-               pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
+       /* Try to set 64-bit DMA first */
+       if (WARN_ON(!pdev->dev.dma_mask))
+               /* Platform did not initialize dma_mask */
+               ret = dma_coerce_mask_and_coherent(&pdev->dev,
+                                                  DMA_BIT_MASK(64));
        else
-               dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
+               ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+
+       /* If seting 64-bit DMA mask fails, fall back to 32-bit DMA mask */
+       if (ret) {
+               ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
+               if (ret)
+                       return ret;
+       }
 
        hcd = usb_create_hcd(driver, &pdev->dev, dev_name(&pdev->dev));
        if (!hcd)