On 7/23/25 10:17 AM, Cristian Ciocaltea wrote:

Hi Roderick,

On 7/23/25 7:04 AM, Roderick Colenbrander wrote:

quoted

Hi Cristian,

Thanks for the information on the audio patches in the sound tree. We
weren't familiar with that part.

I've actually mentioned that in the cover letter and changelog of this
revision.  Couldn't do this previously because I submitted the HID series
before the USB audio one.

quoted

I talked a bit with my team members as well. In general audio is
getting some bigger attention (will see where that goes). I'm getting
a bit worried that the HID and usb driver need much closer coupling,
the current coupling not being enough.

I think we should keep things simple for now, at least until we land the
basic support, also considering the USB part has been already merged.

quoted

I don't know the USB audio spec too well, but it is more on the
digital interface and a DAC. I'm not sure on the exact circuitry on
the DualSense, but there is a lot of logic in the console drivers for
volume handling where adjustment of the volume talks to the HID layer
to send a new output report. I suspect they had very good reasons for
it (e.g. for headphone also dealing with different impedances).

So I'm not sure how the volume control is really supposed to work, but
I would think to do it properly it requires some interaction between
the audio and HID drivers. Just letting the audio side do it right
now, is more about leveraging the range of the DAC I guess versus a
proper audio amplification stage.

Indeed, it's not possible to support hardware volume control from
ALSA/usb-audio without involving HID.  This could be done, or at least it's
worth investigating further, but it's not mandatory and definitely beyond
the scope of the current work.

quoted

Just thinking of things from the user perspective, they should have a
unified volume control. I don't know how other devices are doing it,
but I think we need to think a bit further and we need to reconsider
how things work....

There's a bit more complexity in here than initially anticipated, but the
(software) volume control is not really a problem.  It's worth noting I am
going to provide some UCM changes, part of the ALSA project:

  https://github.com/alsa-project/alsa-ucm-conf

This is to ensure proper support for audio profile switching between
headphones/headset and internal speaker/microphone, which also addresses
a few volume control related issues.  Those are mainly caused by the haptic
feedback functionality, which is controlled by a pair of dedicated channels
in a quadraphonic audio stream.  One of the UCM's main jobs is to split the
4.0 PCM stream into 4 mono channels or a pair of stereo (FL+FR) channels,
depending on the active output device/profile.

The only blocker now is this HID series, which prevents us moving further.

Therefore, unless there is anything else remaining which requires urgent
attention, could you please provide an ack for Jiri to be able to pick this
up?

It's been over a month now since this was kind of blocked without any clear
reason, and by the end of next week I'll be on leave, which means we're
close to missing the merge window once again.

Considering the counterpart quirk in the generic USB audio driver has been
already merged since v6.17, I kindly ask for your support in getting this
into v6.18.

Thanks,
Cristian