Re: Should battery generate events?

[Tim Dijkstra <newsuser-TpnWJeB+oO0hKRfeEwdQzg@public.gmane.org>]

On Tue, 5 Oct 2004 20:28:44 +0200
Tim Dijkstra <newsuser-TpnWJeB+oO0hKRfeEwdQzg@public.gmane.org> wrote:

> On Mon, 04 Oct 2004 15:14:45 -0700
> David Bronaugh <dbronaugh-Jp3n8lUXroSX6QiC4yPwbg@public.gmane.org> wrote:
> 
> > Tim Dijkstra wrote:
> >   
> > >From some googl'ing I get the impression that ACPI should generate
> > >battery events on a change of capacity or at least when it's low.
> > >My idea was to have acpid call some script on battery events. 
> > >The problem is that there doesn't seem to be such events on my
> > >machine. 
> > >  
> > >
> > Whenever polling is required, this is expected to be done in
> > userspace, not in kernelspace. There's a long history of people
> > asking"why doesn't battery status changes generate events" and a
> > long history of people saying "because it would require polling in
> > either acpid or the kernel, which is a Bad Thing(tm)".
> 
> Hmm, sounds reasonable ... But what do these entries in
> /proc/acpi/battery/BAT0/info mean:
> 
> design capacity warning: 30 mAh
> design capacity low:     20 mAh
> 
> it seems to imply to me that there should be a warning of some kind
> when the capacity hits 30 mAh. But if I read your post correctly there
> is no such thing?

Replying to my self here ... 

Readying the ACPI spec I learned there _is_ such a thing, but it's not
required. And browsing through my dsdt I see there's no _BTP method,
which probably means my battery doesn't support that:( 
After reading battery.c I can further reply to myself in my first
post:

> > > Does it have anything to do with
> > > tdykstra@bonenpikster:/$ cat /proc/acpi/battery/BAT0/alarm
> > > alarm:                   unsupported

Yes, this means there's no _BTP and hence no warning events.

So polling is the only option for me ...


grts Tim


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