[pulseaudio-discuss] [PATCH] alsa: make headset-mic scanned earlier than headphone-mic

[Tanu Kaskinen]

On Tue, 2017-05-23 at 11:04 +0800, Hui Wang wrote:
> On 05/20/2017 10:51 PM, Tanu Kaskinen wrote:
> > On Fri, 2017-05-19 at 09:29 +0800, Hui Wang wrote:
> > > Hello Tanu,
> > > 
> > > Could you please help take a look at this patch? This patch really fix
> > > an issue on some Dell machines (with realtek codec and has no internal
> > > microphone on them), And I think this minor change will not introduce
> > > regression, it is pretty safe.
> > 
> > The patch only changes the order in which headset-mic and headphone-mic
> > are listed, and that order should not have any real impact on anything.
> > There's clearly a bug somewhere, but the bug can't be that the paths
> > are listed in the wrong order, since the order should not matter.
> 
> Yes, you are right. In theory, the headset-mic and headphone-mic have 
> the same priority, so exchanging their order should not have any real 
> impact on anything.
> 
> But in practice, this bug exposes that in some situation( when there are 
> only headphone-mic and headset-mic, and neither of them is plugged in.), 
> the headphone-mic is not suitable to be the default active_port.  So do 
> you think if it is acceptable that I don't exchange their order, I just 
> adjust their priorities to make the headset-mic's priority a bit higher 
> than headphone-mic's?

If I understand correctly, headphones and headsets only work with the
headset-mic port, and microphones only work with the headphone-mic
port. Since it's more likely that a user plugs in headphones or a
headset than a microphone, I think it's ok to make the headset-mic
priority a bit higher than headphone-mic.

However, that still doesn't fix the bug properly, I think. What if the
user plugs in a microphone and selects it in the UI? What will make
pulseaudio switch to the headphone-mic? What will make pulseaudio
switch to the headset-mic port if headphones or a headset is plugged in
later?

It sounds like the kernel might be buggy too. Why does it have to
disable headphone output if pulseaudio's active source port happens to
be headphone-mic? The kernel seems to select from two mic modes:
headset or microphone, but I don't understand why it doesn't have a
mode for no mic input at all, which could be used when headphones are
plugged in.

-- 
Tanu

https://www.patreon.com/tanuk