[PATCH 2/2] [media] dvb-usb-firmware: don't do DMA on stack

[Stefan Brüns]

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: Stefan Brüns <stefan.bru...@rwth-aachen.de>
---
 drivers/media/usb/dvb-usb/dvb-usb-firmware.c | 30 ++++++++++++++++------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/drivers/media/usb/dvb-usb/dvb-usb-firmware.c 
b/drivers/media/usb/dvb-usb/dvb-usb-firmware.c
index dd048a7c461c..189b6725edd0 100644
--- a/drivers/media/usb/dvb-usb/dvb-usb-firmware.c
+++ b/drivers/media/usb/dvb-usb/dvb-usb-firmware.c
@@ -35,41 +35,45 @@ static int usb_cypress_writemem(struct usb_device *udev,u16 
addr,u8 *data, u8 le
 
 int usb_cypress_load_firmware(struct usb_device *udev, const struct firmware 
*fw, int type)
 {
-       struct hexline hx;
-       u8 reset;
-       int ret,pos=0;
+       u8 *buf = kmalloc(sizeof(struct hexline), GFP_KERNEL);
+       struct hexline *hx = (struct hexline *)buf;
+       int ret, pos = 0;
+       u16 cpu_cs_register = cypress[type].cpu_cs_register;
 
        /* stop the CPU */
-       reset = 1;
-       if ((ret = 
usb_cypress_writemem(udev,cypress[type].cpu_cs_register,&reset,1)) != 1)
+       buf[0] = 1;
+       if (usb_cypress_writemem(udev, cpu_cs_register, buf, 1) != 1)
                err("could not stop the USB controller CPU.");
 
-       while ((ret = dvb_usb_get_hexline(fw,&hx,&pos)) > 0) {
-               deb_fw("writing to address 0x%04x (buffer: 0x%02x 
%02x)\n",hx.addr,hx.len,hx.chk);
-               ret = usb_cypress_writemem(udev,hx.addr,hx.data,hx.len);
+       while ((ret = dvb_usb_get_hexline(fw, hx, &pos)) > 0) {
+               deb_fw("writing to address 0x%04x (buffer: 0x%02x %02x)\n",
+                      hx->addr, hx->len, hx->chk);
+               ret = usb_cypress_writemem(udev, hx->addr, hx->data, hx->len);
 
-               if (ret != hx.len) {
+               if (ret != hx->len) {
                        err("error while transferring firmware "
                                "(transferred size: %d, block size: %d)",
-                               ret,hx.len);
+                               ret, hx->len);
                        ret = -EINVAL;
                        break;
                }
        }
        if (ret < 0) {
-               err("firmware download failed at %d with %d",pos,ret);
+               err("firmware download failed at %d with %d", pos, ret);
+               kfree(buf);
                return ret;
        }
 
        if (ret == 0) {
                /* restart the CPU */
-               reset = 0;
-               if (ret || 
usb_cypress_writemem(udev,cypress[type].cpu_cs_register,&reset,1) != 1) {
+               buf[0] = 0;
+               if (usb_cypress_writemem(udev, cpu_cs_register, buf, 1) != 1) {
                        err("could not restart the USB controller CPU.");
                        ret = -EINVAL;
                }
        } else
                ret = -EIO;
+       kfree(buf);
 
        return ret;
 }
-- 
2.11.0