linux-kernel - [PATCH] wistron_btns: reduce polling frequency (to save power)

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Message-ID: <46503B69.4080807@tremplin-utc.net>
Date:	Sun, 20 May 2007 14:13:29 +0200
From:	Éric Piel <Eric.Piel@...mplin-utc.net>
To:	Dmitry Torokhov <dtor@...ightbb.com>
CC:	mitr@...ny.cz, linux-kernel@...r.kernel.org
Subject: [PATCH] wistron_btns: reduce polling frequency (to save power)

Hello,

I'm usually not a fashion victim, but I felt into the trap this time: 
I've launched powertop. As I noticed that wistron_btns was part of the 
topers (10 wake-up's per seconds), here is a patch that should reduce 
the problem. The driver now polls the hardware only twice per second.

Actually, I've tried to decrease the timer to 1 Hz, using round_jiffies 
it would have been an even bigger win, but latency was just too big from 
a user point of view. It's pity, there doesn't seem to be any API to 
synchronize a 2 Hz timer with the rounded timers :-(

It should apply against 2.6.22-rc2 (as well as input tree). It's 
completely orthogonal to my previous patch "add led support", so you can 
apply both in the order you like ;-) There is no particular urgency in 
this patch, so I guess you can keep it for 2.6.23.

See you,
Eric

View attachment "wistron_btns-reduce-timer-frequency-2.6.22.patch" of type "text/x-patch" (2162 bytes)