[RFC] sound: add uevent notifications for jack events

[RFC] sound: add uevent notifications for jack events

[Cryolitia PukNgae]

I propose adding uevent notifications for all audio jack events in the
sound subsystem, including headphone and microphone jacks.

The kernel already sends uevents for certain jack types like HDMI,
demonstrating this pattern is well-established. However, other common
audio jacks like headphones and microphones only generate input events,
not uevents.

This inconsistency affects userspace tools that rely on uevents for
device management. Adding uevents for all jack types would provide a
uniform interface for monitoring audio connection state changes.

My proposal is straightforward: extend the existing uevent mechanism to
cover all audio jack plug/unplug events in the sound subsystem. This
change would maintain backward compatibility with existing input event
consumers while providing consistent device notification for all jack
types.

The change aligns with the semantic purpose of uvents - to notify about
hardware state changes. Physical connection events naturally fit this
category.

If there are objections or historical context I should consider, I would
appreciate hearing them.

Thanks.

Best regards,
Cryolitia PukNgae

Re: [RFC] sound: add uevent notifications for jack events

[Takashi Iwai]

On Wed, 29 Oct 2025 09:11:56 +0100,
Cryolitia PukNgae wrote:
> 
> I propose adding uevent notifications for all audio jack events in the
> sound subsystem, including headphone and microphone jacks.
> 
> The kernel already sends uevents for certain jack types like HDMI,
> demonstrating this pattern is well-established. However, other common
> audio jacks like headphones and microphones only generate input events,
> not uevents.
> 
> This inconsistency affects userspace tools that rely on uevents for
> device management. Adding uevents for all jack types would provide a
> uniform interface for monitoring audio connection state changes.
> 
> My proposal is straightforward: extend the existing uevent mechanism to
> cover all audio jack plug/unplug events in the sound subsystem. This
> change would maintain backward compatibility with existing input event
> consumers while providing consistent device notification for all jack
> types.
> 
> The change aligns with the semantic purpose of uvents - to notify about
> hardware state changes. Physical connection events naturally fit this
> category.
> 
> If there are objections or historical context I should consider, I would
> appreciate hearing them.
> 
> Thanks.
> 
> Best regards,
> Cryolitia PukNgae

Honestly speaking, I have a mixed feeling for this approach.
I understand that uevents can be used for handling commonly for all
jack events, but OTOH, it means that we may spam a lot there.

FWIW, as generic jack event handling, there is the notification via
ALSA control API for each sound card, not only the input devices,
too.  If any, we may add yet another notifications on top of that with
uevents; but this must not be enabled blindly.


thanks,

Takashi