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Subject[PATCH v2 23/31] technisat-usb2: use DMA buffers for I2C transfers
Date
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>
---
drivers/media/usb/dvb-usb/technisat-usb2.c | 16 +++++++++++-----
1 file 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,
--
2.7.4

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