Re: nvram polling for hardware mixer

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On Tue, 29 May 2007, Matthew Garrett wrote:
> On Mon, May 28, 2007 at 11:58:24PM +0100, Richard Hughes wrote:
> > I've been hacking to make the nvram hardware buttons on thinkpad exposed
> > as a hardware mixer device. This requires the nvram to be polled in
> > kernel space, and then examined to see if the volume and mute status has
> > changed. I have attached code to export a simple mono tuner, but this
> > needs further testing and integration. I've also prepared a preliminary
> > patch to add the polling to the thinkpad_acpi driver.
> 
> The recent Thinkpads I've played with have all triggered interrupts on 
> IRQ 9 when hitting the nvram hotkeys. ACPI registers this as a shared 
> interrupt, so possibly there's some hope of being able to hook in there? 

Yes, there is.  I have no idea if it is standard across many models or not,
but there is hope.

I'll have to check if I can enable something like an ACPI interrupt tracer
in ACPICA or somesuch.

> I'm not sure if this is the case on all machines, so it might require a 
> table for polling/non-polling behaviour.

Probably.

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh

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