[PATCH 1/2] [usb] make xhci platform driver use 64 bit or 32 bit DMA

Mark Langsdorf
2014-10-30T18:16:28Z

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 <mlangsdo@redhat.com>
---
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