[media] stk-webcam: don't use stack for DMA

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>

1 files changed, 11 insertions, 5 deletions

diff --git a/drivers/media/usb/stkwebcam/stk-webcam.c b/drivers/media/usb/stkwebcam/stk-webcam.c
index db200c9d796d..22a9aae16291 100644
--- a/drivers/media/usb/stkwebcam/stk-webcam.c
+++ b/drivers/media/usb/stkwebcam/stk-webcam.c
@@ -147,20 +147,26 @@ int stk_camera_write_reg(struct stk_camera *dev, u16 index, u8 value)
 int stk_camera_read_reg(struct stk_camera *dev, u16 index, int *value)
 {
         struct usb_device *udev = dev->udev;
+        unsigned char *buf;
         int ret;
 
+        buf = kmalloc(sizeof(u8), GFP_KERNEL);
+        if (!buf)
+                return -ENOMEM;
+
         ret = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0),
                         0x00,
                         USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                         0x00,
                         index,
-                        (u8 *) value,
+                        buf,
                         sizeof(u8),
                         500);
-        if (ret < 0)
-                return ret;
-        else
-                return 0;
+        if (ret >= 0)
+                memcpy(value, buf, sizeof(u8));
+
+        kfree(buf);
+        return ret;
 }
 
 static int stk_start_stream(struct stk_camera *dev)