lkml.org 
[lkml]   [2016]   [Oct]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 29/31] s2255drv: don't use stack for DMA
Date
From: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

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.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
---
drivers/media/usb/s2255/s2255drv.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/s2255/s2255drv.c b/drivers/media/usb/s2255/s2255drv.c
index c3a0e87066eb..f7bb78c1873c 100644
--- a/drivers/media/usb/s2255/s2255drv.c
+++ b/drivers/media/usb/s2255/s2255drv.c
@@ -1901,19 +1901,30 @@ static long s2255_vendor_req(struct s2255_dev *dev, unsigned char Request,
s32 TransferBufferLength, int bOut)
{
int r;
+ unsigned char *buf;
+
+ buf = kmalloc(TransferBufferLength, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
if (!bOut) {
r = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
Request,
USB_TYPE_VENDOR | USB_RECIP_DEVICE |
USB_DIR_IN,
- Value, Index, TransferBuffer,
+ Value, Index, buf,
TransferBufferLength, HZ * 5);
+
+ if (r >= 0)
+ memcpy(TransferBuffer, buf, TransferBufferLength);
} else {
+ memcpy(buf, TransferBuffer, TransferBufferLength);
r = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0),
Request, USB_TYPE_VENDOR | USB_RECIP_DEVICE,
- Value, Index, TransferBuffer,
+ Value, Index, buf,
TransferBufferLength, HZ * 5);
}
+ kfree(buf);
return r;
}

--
2.7.4

\
 
 \ /
  Last update: 2016-10-11 12:13    [W:0.178 / U:0.716 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site