[PATCH v8 3/3] usb: xhci: configure 32-bit DMA if the controller does not support 64-bit DMA

[Duc Dang]

This change avoids DMA error in the cases where dma_mask and
coherent_dma_mask of a 32-bit controller get configured as
DMA_BIT_MASK(64) when running on a 64-bit system.

Signed-off-by: Duc Dang <dhdang at apm.com>
---
 drivers/usb/host/xhci.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 6b0f4a4..8cb8f39 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4908,6 +4908,16 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
 			!dma_set_mask(dev, DMA_BIT_MASK(64))) {
 		xhci_dbg(xhci, "Enabling 64-bit DMA addresses.\n");
 		dma_set_coherent_mask(dev, DMA_BIT_MASK(64));
+	} else {
+		/*
+		 * This is to avoid error in cases where a 32-bit USB
+		 * controller is used on a 64-bit capable system.
+		 */
+		retval = dma_set_mask(dev, DMA_BIT_MASK(32));
+		if (retval)
+			return retval;
+		xhci_dbg(xhci, "Enabling 32-bit DMA addresses.\n");
+		dma_set_coherent_mask(dev, DMA_BIT_MASK(32));
 	}
 
 	xhci_dbg(xhci, "Calling HCD init\n");
-- 
1.9.1