[ltp] [PATCH] In-kernel automatic fan control

[Yury Polyanskiy]

Oops, you're right of course!

I'll combine this fix with latest version of ibm-acpi (0.12a?) and
repost patch if you want. 

I also have some thoughts on using fan-speed control feature with
kautofand. Do you think there could be any advantage in using more
finegrained fan speed control (than current on/off)?

Personally I doubt there will be any advantage. Since our criterion of
optimality is amount of noise produced by fan (integrated over time).
And this cost function has very high value even for "level 1". In other
words it is better to use high fan speed for shorter periods of time.

Yury.

On Tue, 2005-11-29 at 23:22 +0100, Ziga Mahkovec wrote:
> On Mon, 2005-11-28 at 20:01 -0500, Yury Polyanskiy wrote:
> > I did a small modification to a kernel ibm-acpi driver. 
> > It adds "auto" command for fan (in addition to enable/disable). 
> > [...]
> > Patch against mainstream ibm-acpi-0.11.tar.gz attached.
> 
> I'm trying out your patch on T43p and so far it works great.
> 
> Minor comment:
> 
> > +  int ret = __thermal_raw_read(tmp);
> > +  if(ret){
> > +  	printk(IBM_ERR "kautofand: can't read temperatures, ret = %d\n", ret);
> > +  	errors++;
> > +  	if(errors > 10) break;
> > +  }
> 
> Would it make sense to start the fan here, before breaking out?  If I'm
> reading this correctly, this code path allows for kautofand to be
> stopped without the fan ever being started back up.
> 
> Thanks,
> -- 
> Ziga
>