lkml.org 
[lkml]   [2016]   [Oct]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v2 28/31] cpia2_usb: don't use stack for DMA
Date
Hi,

> 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/cpia2/cpia2_usb.c | 32 +++++++++++++++++++++++++++++---
> 1 file changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/usb/cpia2/cpia2_usb.c b/drivers/media/usb/cpia2/cpia2_usb.c
> index 13620cdf0599..417d683b237d 100644
> --- a/drivers/media/usb/cpia2/cpia2_usb.c
> +++ b/drivers/media/usb/cpia2/cpia2_usb.c
> @@ -545,10 +545,19 @@ static void free_sbufs(struct camera_data *cam)
> static int write_packet(struct usb_device *udev,
> u8 request, u8 * registers, u16 start, size_t size)
> {
> + unsigned char *buf;
> + int ret;
> +
> if (!registers || size <= 0)
> return -EINVAL;
>
> - return usb_control_msg(udev,
> + buf = kmalloc(size, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + memcpy(buf, registers, size);
> +
> + ret = usb_control_msg(udev,
> usb_sndctrlpipe(udev, 0),
> request,
> USB_TYPE_VENDOR | USB_RECIP_DEVICE,
> @@ -557,6 +566,9 @@ static int write_packet(struct usb_device *udev,
> registers, /* buffer */
=========

I think you also want to change the argument to usb_control_msg() from
"registers" to "buf" in write_packet().


> size,
> HZ);
> +
> + kfree(buf);
> + return ret;
> }
..
---
Kosuke TATSUKAWA | 1st Platform Software Division
| NEC Solution Innovators
| tatsu@ab.jp.nec.com

\
 
 \ /
  Last update: 2016-10-12 00:57    [W:0.192 / U:2.472 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site