[alsa-devel] Headset button mapping in the kernel

[Mads Lønsethagen]

On 25.11.2019 20:25, Curtis Malainey wrote:
> Hello ALSA Devs,
> 
> I am looking to get some feedback/ideas on a possible change to
> headset button mapping. Locally we are carrying patches that implement
> the mappings in the machine driver (which we understand you do not
> want upstream.) We are looking to see if we can add a new API
> (something like a sysfs path potentially) to have userspace pass in
> the mapping, if it chooses to, so the mapping can still be done in the
> kernel. That way we can carry just the config locally and remove some
> of the kernel patches we are carrying locally. Thanks.
> 
> Curtis
> 

Sorry for the top posting in my last mail.

I just wondered, do this have anything to do with headphones that has 
physical buttons on the headphone wire itself? E.g the Bose QC25 is a 
pair of headphones that has four buttons on the wire, and as far as I 
can see there's no way of getting those buttons to work in vanilla Linux 
for now, but it works in Android and Windows 10.

I asked about this on this mailing list before[1], because I don't even 
know which component should be responsible for generating button events. 
Should it have anything to do with alsa? Is the button mapping you're 
asking about here about the same thing? Do anyone know how one should go 
about supporting these kind of button events on desktop Linux?

- Mads

[1] 
https://mailman.alsa-project.org/pipermail/alsa-devel/2019-October/157702.html