public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
From: "Németh Márton" <nm127@freemail.hu>
To: mschimek@gmx.at, video4linux-list@redhat.com
Cc: LKML <linux-kernel@vger.kernel.org>, em28xx@mcentral.de
Subject: parameter of VIDIOC_G_INPUT and VIDIOC_S_INPUT?
Date: Tue, 16 Dec 2008 08:13:26 +0100	[thread overview]
Message-ID: <49475516.3090504@freemail.hu> (raw)

Hi,

I have a question about the parameter of VIDIOC_G_INPUT and VIDIOC_S_INPUT
parameters in v4l2 specification.

The "Video for Linux Two API Specification" text says that the
parameter of VIDIOC_G_INPUT and VIDIOC_S_INPUT is ...

> [...] a pointer to an integer where the driver stores the number
> of the input, as in the struct v4l2_input index field.
>
> http://v4l2spec.bytesex.org/spec/r11217.htm

In the v4l2_input structure the index has the type of __u32.

In contrast, in <linux/videodev2.h> (as of 2.6.27) the ioctls are defined
as follows:

> #define VIDIOC_G_INPUT		_IOR('V', 38, int)
> #define VIDIOC_S_INPUT		_IOWR('V', 39, int)

The problem is that '__u32' is unsigned and 'int' is signed. Furthermore
one cannot be sure that sizeof(__u32) == sizeof(int) on all platforms.

I guess that the parameter of VIDIOC_G_INPUT and VIDIOC_S_INPUT should be
a pointer to __u32. What do you think?

Regards,

	Márton Németh

             reply	other threads:[~2008-12-16  7:13 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-12-16  7:13 Németh Márton [this message]
2008-12-16  8:01 ` [Em28xx] parameter of VIDIOC_G_INPUT and VIDIOC_S_INPUT? Markus Rechberger

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=49475516.3090504@freemail.hu \
    --to=nm127@freemail.hu \
    --cc=em28xx@mcentral.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mschimek@gmx.at \
    --cc=video4linux-list@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox