Re: [PATCH] Video/UVC: Fix unaligned exceptions in uvc video driver.

[Bryan Wu]

On Sun, Nov 9, 2008 at 8:55 PM, Laurent Pinchart
<laurent.pinchart@xxxxxxxxx> wrote:
> Hi Bryan, Michael,
>
> Thanks for the patch.
>
> On Thursday 06 November 2008, Bryan Wu wrote:
>> From: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
>>
>> buffer can be odd aligned on some NOMMU machine such as Blackfin
>
> The comment is a bit misleading. Buffers can be odd-aligned independently off
> the machine type. The issue comes from machines that can't access unaligned
> memory. Something like "Fix access to unaligned memory" would be better.
>
>> Signed-off-by: Michael Hennerich <michael.hennerich@xxxxxxxxxx>
>> Signed-off-by: Bryan Wu <cooloney@xxxxxxxxxx>
>> ---
>>  drivers/media/video/uvc/uvc_driver.c |   37
>> +++++++++++++++++---------------- 1 files changed, 19 insertions(+), 18
>> deletions(-)
>>
>> diff --git a/drivers/media/video/uvc/uvc_driver.c
>> b/drivers/media/video/uvc/uvc_driver.c index d7ad060..9b4f469 100644
>> --- a/drivers/media/video/uvc/uvc_driver.c
>> +++ b/drivers/media/video/uvc/uvc_driver.c
>> @@ -31,6 +31,7 @@
>>  #include <linux/videodev2.h>
>>  #include <linux/vmalloc.h>
>>  #include <linux/wait.h>
>> +#include <asm/unaligned.h>
>>  #include <asm/atomic.h>
>>
>>  #include <media/v4l2-common.h>
>> @@ -432,20 +433,20 @@ static int uvc_parse_format(struct uvc_device *dev,
>>
>>               frame->bFrameIndex = buffer[3];
>>               frame->bmCapabilities = buffer[4];
>> -             frame->wWidth = le16_to_cpup((__le16 *)&buffer[5]);
>> -             frame->wHeight = le16_to_cpup((__le16 *)&buffer[7]);
>> -             frame->dwMinBitRate = le32_to_cpup((__le32 *)&buffer[9]);
>> -             frame->dwMaxBitRate = le32_to_cpup((__le32 *)&buffer[13]);
>> +             frame->wWidth = le16_to_cpu(get_unaligned((__le16 *) &buffer[5]));
>
> What about using get_unaligned_le16 and get_unaligned_le32 directly ? Lines
> would be shorter and could be kept behind the 80 columns limit more easily.
>
> Tell me if you want to resubmit or if I should make the modification myself
> (including the patch description).
>

I guess Michael will update this patch according to you review. Then
we will resubmit it.

Thanks a lot
-Bryan
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