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

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Message-ID: <4A2934F5.4050601@tuffmail.co.uk>
Date:	Fri, 05 Jun 2009 16:08:37 +0100
From:	Alan Jenkins <alan-jenkins@...fmail.co.uk>
To:	Pekka Enberg <penberg@...helsinki.fi>
CC:	Corentin Chary <corentin.chary@...il.com>,
	acpi4asus-user@...ts.sourceforge.net, len.brown@...el.com,
	linux-kernel@...r.kernel.org, USB list <linux-usb@...r.kernel.org>
Subject: Re: [PATCH] eeepc-laptop: enable camera by default

Alan Jenkins wrote:
> Pekka Enberg wrote:
>> Hi Alan,
>>
>> On Fri, 2009-06-05 at 15:38 +0100, Alan Jenkins wrote:
>>  
>>> Ok.  I didn't bother shutting down my system, but I get a similar
>>> difference; 16 wakeups/s disabled v.s. 25 enabled.  Anecdotally,
>>> disabling the camera does help battery life, and presumably Asus had
>>> good reason to implement it!  (The shipped OS "fixes" the usability
>>> problem by patching the camera apps).
>>>
>>> BUT I found that autosuspend didn't seem to break anything, and
>>> enabling it also got me down to 16 wakeups/s.  I think this is ideal
>>> because autosuspend is automatic so I can save power without manual
>>> toggling.
>>>
>>> Here's some magic to enable autosuspend:
>>>
>>> # echo -n auto > /sys/bus/usb/drivers/uvcvideo/*:*/../power/level
>>>
>>> Ideally this wants to be enabled automatically using a udev rule.
>>>     
>>
>> Can the kernel do this by default for this specific driver on eeepc?
>>
>>             Pekka
>>
>>   
>
> Auto-suspend white-listing would be done on the basis of USB ids 
> (vendor, product).  At the moment it's expected that userspace should 
> take ownership of it.  There's no infrastructure for in-kernel 
> whitelisting.  I think.
>
> Large lists in udev rules can work, there are already lists of USB 
> devices to set permissions for libusb access, e.g. for libmtp.
>
> [CC usb list - in the hope someone will point out if I got this wrong 
> :-)]
>
> Alan

Btw I've now tested the udev rule, you can just dump this in a new 
.rules file under /etc/udev/rules.d:

SUBSYSTEM=="usb", ATTR{idVendor}=="eb1a", ATTR{idProduct}=="2761", ATTR{power/level}="auto"


Not sure who I should submit it to though :-).  debian-eeepc would take 
it, but perhaps it should go in udev's default rules.

Regards
Alan
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