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

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Message-Id: <1244214853.23533.43.camel@penberg-laptop>
Date:	Fri, 05 Jun 2009 18:14:13 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Alan Jenkins <alan-jenkins@...fmail.co.uk>
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>,
	kay.sievers@...y.org
Subject: Re: [PATCH] eeepc-laptop: enable camera by default

Hi Alan,

On Fri, 2009-06-05 at 16:08 +0100, Alan Jenkins wrote:
> 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.

AFAIK, Kay Sievers maintains the udev rules so lets cc him. And yeah, I
totally agree that it should go to the generic ones, not to
debian-eeepc.

			Pekka

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