[PATCH v3 1/2] usb:dwc3: Enable support for 64-bit system

["Thang Q. Nguyen" <tqnguyen@apm.com>]

From: "Thang Q. Nguyen" <tqnguyen@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 <tqnguyen@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