linux-kernel - Re: converting appletouch to usb autosuspend...

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Date:	Sat, 12 May 2007 22:47:44 +0100
From:	Alistair John Strachan <s0348365@....ed.ac.uk>
To:	Soeren Sonnenburg <kernel@....de>
Cc:	linux-usb-devel@...ts.sourceforge.net,
	Linux Kernel <linux-kernel@...r.kernel.org>, maxk@...lcomm.com
Subject: Re: converting appletouch to usb autosuspend...

On Saturday 12 May 2007 19:51:26 Soeren Sonnenburg wrote:
> Dear all,
>
> I've realized using the great powertop ( http://www.linuxpowertop.org/ )
> that loading the appletouch driver (and touching it once) makes consumes
> about 0.3 W even when not touching the pad. As rmmod'ing appletouch
> fixes this I wonder why the driver does not do this alone. So my
> question is what does one have to do to convert a driver (such as
> appletouch) to make use of usb autosuspend except for
>
>  .supports_autosuspend = 1
>
> ...
>
> While we are at it usb related powerhogs on this macbook pro are
> uhci_hcd (usb keyboard) and usb_hcd_poll_rh_status (rh_timer_func)
> too...

I've found that hci_usb also hogs power on the Macbook; blacklisting this 
module cuts down HZ considerably. I also found appletouch consumed ticks, 
just as you did.

uhci_hcd then drops to noise; my Macbook's sitting on 10W with the backlight 
on minimum, which is about what it can manage in OS X on maximum life 
settings.

-- 
Cheers,
Alistair.

Final year Computer Science undergraduate.
1F2 55 South Clerk Street, Edinburgh, UK.
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