[PATCH] media: gl861: fix probe of dvb_usb_gl861

[mika . batsman]

From: Mika Båtsman <mika.bats...@gmail.com>

Probe of dvb_usb_gl861 was working at least with v4.4. Noticed the issue
with v4.13 but according to similar issues the problem started with v4.9.

[   15.288065] transfer buffer not dma capable
[   15.288090] WARNING: CPU: 2 PID: 493 at drivers/usb/core/hcd.c:1595 
usb_hcd_map_urb_for_dma+0x4e2/0x640
...CUT...
[   15.288791] dvb_usb_gl861: probe of 3-7:1.0 failed with error -5

Tested with MSI Mega Sky 580 DVB-T Tuner [GL861]

Cc: sta...@vger.kernel.org
Signed-off-by: Mika Båtsman <mika.bats...@gmail.com>
---
 drivers/media/usb/dvb-usb-v2/gl861.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/dvb-usb-v2/gl861.c 
b/drivers/media/usb/dvb-usb-v2/gl861.c
index b1b09c5..0a988e3 100644
--- a/drivers/media/usb/dvb-usb-v2/gl861.c
+++ b/drivers/media/usb/dvb-usb-v2/gl861.c
@@ -20,15 +20,22 @@ static int gl861_i2c_msg(struct dvb_usb_device *d, u8 addr,
        u16 value = addr << (8 + 1);
        int wo = (rbuf == NULL || rlen == 0); /* write-only */
        u8 req, type;
+       int ret;
+       void *dmadata;
 
        if (wo) {
                req = GL861_REQ_I2C_WRITE;
                type = GL861_WRITE;
+               dmadata = kmemdup(wbuf, wlen, GFP_KERNEL);
        } else { /* rw */
                req = GL861_REQ_I2C_READ;
                type = GL861_READ;
+               dmadata = kmalloc(rlen, GFP_KERNEL);
        }
 
+       if (!dmadata)
+               return -ENOMEM;
+
        switch (wlen) {
        case 1:
                index = wbuf[0];
@@ -45,8 +52,14 @@ static int gl861_i2c_msg(struct dvb_usb_device *d, u8 addr,
 
        msleep(1); /* avoid I2C errors */
 
-       return usb_control_msg(d->udev, usb_rcvctrlpipe(d->udev, 0), req, type,
-                              value, index, rbuf, rlen, 2000);
+       ret = usb_control_msg(d->udev, usb_rcvctrlpipe(d->udev, 0), req, type,
+                              value, index, dmadata, rlen, 2000);
+
+       if (!wo)
+               memcpy(rbuf, dmadata, rlen);
+
+       kfree(dmadata);
+       return ret;
 }
 
 /* I2C */
-- 
2.7.4