This is a note to let you know that I've just added the patch titled
[media] cxusb: Use a dma capable buffer also for reading
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cxusb-use-a-dma-capable-buffer-also-for-reading.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 3f190e3aec212fc8c61e202c51400afa7384d4bc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20Br=C3=BCns?= <stefan.bruens@xxxxxxxxxxxxxx>
Date: Sun, 5 Feb 2017 12:57:59 -0200
Subject: [media] cxusb: Use a dma capable buffer also for reading
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
From: Stefan Brüns <stefan.bruens@xxxxxxxxxxxxxx>
commit 3f190e3aec212fc8c61e202c51400afa7384d4bc upstream.
Commit 17ce039b4e54 ("[media] cxusb: don't do DMA on stack")
added a kmalloc'ed bounce buffer for writes, but missed to do the same
for reads. As the read only happens after the write is finished, we can
reuse the same buffer.
As dvb_usb_generic_rw handles a read length of 0 by itself, avoid calling
it using the dvb_usb_generic_read wrapper function.
Signed-off-by: Stefan Brüns <stefan.bruens@xxxxxxxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Brad Spengler <spender@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/media/usb/dvb-usb/cxusb.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
--- a/drivers/media/usb/dvb-usb/cxusb.c
+++ b/drivers/media/usb/dvb-usb/cxusb.c
@@ -59,23 +59,24 @@ static int cxusb_ctrl_msg(struct dvb_usb
u8 cmd, u8 *wbuf, int wlen, u8 *rbuf, int rlen)
{
struct cxusb_state *st = d->priv;
- int ret, wo;
+ int ret;
if (1 + wlen > MAX_XFER_SIZE) {
warn("i2c wr: len=%d is too big!\n", wlen);
return -EOPNOTSUPP;
}
- wo = (rbuf == NULL || rlen == 0); /* write-only */
+ if (rlen > MAX_XFER_SIZE) {
+ warn("i2c rd: len=%d is too big!\n", rlen);
+ return -EOPNOTSUPP;
+ }
mutex_lock(&d->data_mutex);
st->data[0] = cmd;
memcpy(&st->data[1], wbuf, wlen);
- if (wo)
- ret = dvb_usb_generic_write(d, st->data, 1 + wlen);
- else
- ret = dvb_usb_generic_rw(d, st->data, 1 + wlen,
- rbuf, rlen, 0);
+ ret = dvb_usb_generic_rw(d, st->data, 1 + wlen, st->data, rlen, 0);
+ if (!ret && rbuf && rlen)
+ memcpy(rbuf, st->data, rlen);
mutex_unlock(&d->data_mutex);
return ret;
Patches currently in stable-queue which might be from stefan.bruens@xxxxxxxxxxxxxx are
queue-4.9/dvb-usb-firmware-don-t-do-dma-on-stack.patch
queue-4.9/cxusb-use-a-dma-capable-buffer-also-for-reading.patch