linux-kernel - Re: [PATCH 2/2] video: simplify cx18_get_input() and ivtv_get

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Message-Id: <200810132349.06834.hverkuil@xs4all.nl>
Date:	Mon, 13 Oct 2008 23:49:06 +0200
From:	Hans Verkuil <hverkuil@...all.nl>
To:	Robert William Fuller <hydrologiccycle@...il.com>
Cc:	Németh Márton <nm127@...email.hu>,
	video4linux-list@...hat.com, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] video: simplify cx18_get_input() and	ivtv_get_input()

On Monday 13 October 2008 23:40:48 Robert William Fuller wrote:
> Hans Verkuil wrote:
> > On Monday 13 October 2008 22:54:06 Németh Márton wrote:
> >> From: Márton Németh <nm127@...email.hu>
> >>
> >> The cx18_get_input() and ivtv_get_input() are called
> >> once from the VIDIOC_ENUMINPUT ioctl() and once from
> >> the *_log_status() functions. In the first case the
> >> struct v4l2_input is already filled with zeros,
> >> so doing this again is unnecessary.
> >
> > And in the second case no one cares whether the struct is zeroed.
> > And the same situation is also true for ivtv_get_output().
>
> Yeah, 'cos there's nothing better than uninitialized fields, like the
> recent report of a control that returns minimum and maximum values of
> zero, but a step-size of 9.  Why are we optimizing code paths that
> are not performance critical by uninitializing memory?

It's already initialized to 0 in v4l2-ioctl.c. No need to do it twice. 

Regards,

	Hans
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