[media] technisat-usb2: use DMA buffers for I2C transfers

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.

On this driver, most of the transfers are OK, but the I2C
one was using stack.

Reviewed-by: Patrick Boettcher <patrick.boettcher@posteo.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 11 insertions, 5 deletions

diff --git a/drivers/media/usb/dvb-usb/technisat-usb2.c b/drivers/media/usb/dvb-usb/technisat-usb2.c
index d9f3262bf071..4706628a3ed5 100644
--- a/drivers/media/usb/dvb-usb/technisat-usb2.c
+++ b/drivers/media/usb/dvb-usb/technisat-usb2.c
@@ -89,9 +89,13 @@ struct technisat_usb2_state {
 static int technisat_usb2_i2c_access(struct usb_device *udev,
                 u8 device_addr, u8 *tx, u8 txlen, u8 *rx, u8 rxlen)
 {
-        u8 b[64];
+        u8 *b;
         int ret, actual_length;
 
+        b = kmalloc(64, GFP_KERNEL);
+        if (!b)
+                return -ENOMEM;
+
         deb_i2c("i2c-access: %02x, tx: ", device_addr);
         debug_dump(tx, txlen, deb_i2c);
         deb_i2c(" ");
@@ -123,7 +127,7 @@ static int technisat_usb2_i2c_access(struct usb_device *udev,
 
         if (ret < 0) {
                 err("i2c-error: out failed %02x = %d", device_addr, ret);
-                return -ENODEV;
+                goto err;
         }
 
         ret = usb_bulk_msg(udev,
@@ -131,7 +135,7 @@ static int technisat_usb2_i2c_access(struct usb_device *udev,
                         b, 64, &actual_length, 1000);
         if (ret < 0) {
                 err("i2c-error: in failed %02x = %d", device_addr, ret);
-                return -ENODEV;
+                goto err;
         }
 
         if (b[0] != I2C_STATUS_OK) {
@@ -140,7 +144,7 @@ static int technisat_usb2_i2c_access(struct usb_device *udev,
                 if (!(b[0] == I2C_STATUS_NAK &&
                                 device_addr == 0x60
                                 /* && device_is_technisat_usb2 */))
-                        return -ENODEV;
+                        goto err;
         }
 
         deb_i2c("status: %d, ", b[0]);
@@ -154,7 +158,9 @@ static int technisat_usb2_i2c_access(struct usb_device *udev,
 
         deb_i2c("\n");
 
-        return 0;
+err:
+        kfree(b);
+        return ret;
 }
 
 static int technisat_usb2_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msg,