lkml.org 
[lkml]   [2007]   [Sep]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] v4l: fix build error for et61x251 driver
> through ioctl()? It's not as immediate and safe as controlling the device
> registers through /sysfs (not /proc). However, the sysfs interface in those
> drivers appeared before V4L2 had its own ioctls and we agreed to keep and
> export the interface to the only users selecting CONFIG_VIDEO_ADV_DEBUG (ok,
> this is actually valid for the sn9c102, I'll submit a patch for the et61x251
> in the future).

Direct register access for debug ok, but not this is not ok for
normal usage.
>
>
>> From my POV, a driver that is creating its own userspace API is not
>> fully compliant with V4L2 API.
>
> Isn't Video4Linux2 ioctl() supersedeing sysfs in this case?

It should be. However, things like direct register access (for non-debug
mode) may allow some controls that weren't visible via ioctl. That's why
the sysfs usage may be evil: a driver may have some parts accessible only
via sysfs interface, on a non-standard way, without offering the official
API support. So, some device functionalities may be hidden from userspace
apps that are compliant with V4L2.

Summarizing:

Linus patch seems to be the better solution to solve the V4L1_COMPAT bug.

I would also convert the other container_of stuff to to_video_device (to
have code uniformity).

et61x251 direct register interfaces should be available only if
CONFIG_VIDEO_ADV_DEBUG is selected to avoid its miss-usage. If there are
other device configurations that needs specific register settings not yet
provided, this should be provided via V4L2 standard ioctls.

This way, et61x251 will be compliant with V4L2.

I still think that we should work at the remaining sysfs classes to make
them coherent on all V4L devices.

Cheers,
Mauro.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-09-14 17:59    [W:0.039 / U:0.280 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site