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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: 3+ 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
2008-12-16  8:01   ` Markus Rechberger

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