linux-kernel - Re: [PATCH] eeepc-laptop: enable camera by default

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Date:	Fri, 5 Jun 2009 14:39:09 +0100
From:	Alan Jenkins <sourcejedi.lkml@...glemail.com>
To:	Corentin Chary <corentin.chary@...il.com>
Cc:	Pekka Enberg <penberg@...helsinki.fi>,
	acpi4asus-user@...ts.sourceforge.net, len.brown@...el.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] eeepc-laptop: enable camera by default

On 6/5/09, Corentin Chary <corentin.chary@...il.com> wrote:
> On Fri, Jun 5, 2009 at 2:44 PM, Pekka Enberg<penberg@...helsinki.fi> wrote:
>> Hi Corentin,
>>
>> On Fri, 2009-06-05 at 13:46 +0200, Corentin Chary wrote:
>>> First, I think a one line
>>> set_acpi(CM_ASL_CAMERA, 1);
>>> with a small comment is better. (If it fails, it's because there no
>>> camera, so we don't mind).
>>
>> OK, I've included an updated version of the patch.
>>
>> On Fri, 2009-06-05 at 13:46 +0200, Corentin Chary wrote:
>>> Anyway, I'm not sure it's a good idea to enable the camera by default.
>>> It depends how many power the camera is using (when idle). Coud you
>>> check that (with power top maybe ?).
>>
>> People who prefer power savings over functional camera can always
>> disable it. If you look at the amount of "my camera doesn't" work bug
>> reports, I think it's pretty evident that we should enable it by default
>> or provide a config option that does it.
>
> Ok, your right, I'll apply that one
>
>> That said, I am more than happy to measure this but I need a little bit
>> more information to get started as I have never used powertop. So what
>> is it exactly you want me to do?
>
> PowerTop (with a corretly configured kernel) will give you a power
> usage estimate.
>
> CONFIG_NO_HZ=y
> CONFIG_TIMER_STATS=y
> CONFIG_DEBUG_KERNEL=y
>
> For propers results, shutdown all services and just keep a shell
> (without X or network).
> You can also test that with and without the camera driver.

Hmm, this relies on good acpi battery information, I hope your EeePC
is better than mine in that regard.

The ideal solution is if USB auto-suspend could be used to save the
same amount.  Google says there was a patch for uvcvideo last year
[1].  I'll see what the current status is on my model and report back
:-).

[1] <http://lists.berlios.de/pipermail/linux-uvc-devel/2008-January/002707.html>

Alan
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