Re: add lowpower_idle sysctl

[Ross Dickson <ross@datscreative.com.au>]

<snip>
> OK, so why not give us: 
 > 
 > #define IDLE_HALT 0 
 > #define IDLE_POLL 1 
 > #define IDLE_SUPER_LOW_POWER_HALT 2 
 > 
 > and so forth (are there any others?).

#define IDLE_C1HALT ?
 
I created another one for Athlon Nforce2 to prevent lockups in apic mode.
It is proving more useful than I thought.
It has also been used on SIS740 to prevent same problem.
I know such a workaround should not be required but it works well.

It modifies C1 state idle behaviour by being a little more intelligent about
when it is worthwhile to do into disconnect and has a crude but effective
delay in case of back to back disconnect reconnect cycles.
Recent post.
http://linux.derkeiler.com/Mailing-Lists/Kernel/2004-03/4278.html
Patch is here.
http://linux.derkeiler.com/Mailing-Lists/Kernel/2004-02/6520.html 

Currently it is kernel arg activated by  "idle=C1halt".
 
 > 
 > Set some system-wide integer via a sysctl and let the particular 
 > architecture decide how best to implement the currently-selected idle mode? 
 
A lockup detector on Athlon systems could conceivably invoke above idle state
after a manual reboot as not all systems of the same chipset have the problem.

Ross.