Re: nvram polling for hardware mixer

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On Fri, 2007-06-15 at 01:06 -0300, Henrique de Moraes Holschuh wrote:
> 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? 
> > I'm not sure if this is the case on all machines, so it might require a 
> > table for polling/non-polling behaviour.
> 
> Err... not only we CAN get them using interrupts, it was already sort of
> working(!).  Try an echo 0xffffffff > /proc/acpi/ibm/hotkeys, and watch the
> weird ACPI events it generates when you press the volume keys, etc.

Ohh wow. Good catch. I only ever played with low bytes of hotkeys, I
never tried FFFFFFFF!

> I have a patch that fixes and documents the whole stuff almost ready, it
> will be pushed to the git tree soon.

So, we still use a hardware mixer? That still makes most sense from my
point of view as the events are still hardware.

> BTW, I also got events for the LID switch on the same code path in a T43,
> now.  I will be adding EV_SW to thinkpad-acpi soon :p

Okay cool. Could you give me a sneak peek at the patch, so I can try it
on my x60?

Thanks,

Richard.



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