diff options
Diffstat (limited to '1-2-media-cxusb-Use-a-dma-capable-buffer-also-for-reading.patch')
| -rw-r--r-- | 1-2-media-cxusb-Use-a-dma-capable-buffer-also-for-reading.patch | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/1-2-media-cxusb-Use-a-dma-capable-buffer-also-for-reading.patch b/1-2-media-cxusb-Use-a-dma-capable-buffer-also-for-reading.patch new file mode 100644 index 000000000..a3dec80d2 --- /dev/null +++ b/1-2-media-cxusb-Use-a-dma-capable-buffer-also-for-reading.patch @@ -0,0 +1,63 @@ +From patchwork Sun Feb 5 14:57:59 2017 +Content-Type: text/plain; charset="utf-8" +MIME-Version: 1.0 +Content-Transfer-Encoding: 8bit +Subject: [1/2,media] cxusb: Use a dma capable buffer also for reading +From: =?utf-8?q?Stefan_Br=C3=BCns?= <stefan.bruens@rwth-aachen.de> +X-Patchwork-Id: 39207 +Message-Id: <b638428812af41e080ccfc7cf7ad6963@rwthex-w2-b.rwth-ad.de> +To: <linux-media@vger.kernel.org> +Cc: <linux-kernel@vger.kernel.org>, Mauro Carvalho Chehab <mchehab@kernel.org>, + Michael Krufky <mkrufky@linuxtv.org>, + =?UTF-8?q?Stefan=20Br=C3=BCns?= <stefan.bruens@rwth-aachen.de> +Date: Sun, 5 Feb 2017 15:57:59 +0100 + +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@rwth-aachen.de> +--- + drivers/media/usb/dvb-usb/cxusb.c | 15 ++++++++------- + 1 file changed, 8 insertions(+), 7 deletions(-) + +diff --git a/drivers/media/usb/dvb-usb/cxusb.c b/drivers/media/usb/dvb-usb/cxusb.c +index 9b8c82d94b3f..8f28a63597bd 100644 +--- 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_device *d, + 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; |