From: "Thang Q. Nguyen" <tqngu...@apm.com>

Add 64-bit DMA operation support to the USB DWC3 driver.
First attempt to set the coherent DMA mask for 64-bit DMA.
If that failed, attempt again with 32-bit DMA.

Changes from v2:
        - None.

Changes from v1:
        - Remove WARN_ON if dma_mask is NULL

Signed-off-by: Thang Q. Nguyen <tqngu...@apm.com>
---
 drivers/usb/dwc3/core.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index de5e01f..2479c24 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -831,6 +831,21 @@ static int dwc3_probe(struct platform_device *pdev)
        dwc->mem = mem;
        dwc->dev = dev;
 
+       /* Try to set 64-bit DMA first */
+       if (!pdev->dev.dma_mask)
+               /* Platform did not initialize dma_mask */
+               ret = dma_coerce_mask_and_coherent(&pdev->dev,
+                                                  DMA_BIT_MASK(64));
+       else
+               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;
+       }
+
        res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
        if (!res) {
                dev_err(dev, "missing IRQ\n");
-- 
2.2.0

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