[PATCH v2 29/31] s2255drv: don't use stack for DMA

[Mauro Carvalho Chehab <mchehab@s-opensource.com>]

From: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

The USB control messages require DMA to work. We cannot pass
a stack-allocated buffer, as it is not warranted that the
stack would be into a DMA enabled area.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
---
 drivers/media/usb/s2255/s2255drv.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/s2255/s2255drv.c b/drivers/media/usb/s2255/s2255drv.c
index c3a0e87066eb..f7bb78c1873c 100644
--- a/drivers/media/usb/s2255/s2255drv.c
+++ b/drivers/media/usb/s2255/s2255drv.c
@@ -1901,19 +1901,30 @@ static long s2255_vendor_req(struct s2255_dev *dev, unsigned char Request,
 			     s32 TransferBufferLength, int bOut)
 {
 	int r;
+	unsigned char *buf;
+
+	buf = kmalloc(TransferBufferLength, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
 	if (!bOut) {
 		r = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
 				    Request,
 				    USB_TYPE_VENDOR | USB_RECIP_DEVICE |
 				    USB_DIR_IN,
-				    Value, Index, TransferBuffer,
+				    Value, Index, buf,
 				    TransferBufferLength, HZ * 5);
+
+		if (r >= 0)
+			memcpy(TransferBuffer, buf, TransferBufferLength);
 	} else {
+		memcpy(buf, TransferBuffer, TransferBufferLength);
 		r = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
 				    Request, USB_TYPE_VENDOR | USB_RECIP_DEVICE,
-				    Value, Index, TransferBuffer,
+				    Value, Index, buf,
 				    TransferBufferLength, HZ * 5);
 	}
+	kfree(buf);
 	return r;
 }
 
-- 
2.7.4