sound(4): implement playback/recording mode sysctl

[christos]

Summary

The dev.pcm.N.mode sysctl lets us know the playback/recording mode of a sound device (none, play, rec, play+rec).

[• hselasky]

I think s/status/feature/ is a better word?

What do you think?

--HPS

[christos]

In D31320#705392, @hselasky wrote:

I think s/status/feature/ is a better word?

What do you think?

--HPS

"feature" is not clear enough in my opinion.

[• hselasky]

Are there other options for naming.

Status is usually something that can change. But this is more like a property.

[christos]

In D31320#705399, @hselasky wrote:

Are there other options for naming.

Status is usually something that can change. But this is more like a property.

True. "status" does match with "playback/recording status" but it does also imply variability. I cannot come up with a better name for it at the moment though.

[• hselasky]

Could you check an english dictionary with synonyms?

[christos]

In D31320#705403, @hselasky wrote:

Could you check an english dictionary with synonyms?

function, action or operation could also be options.

[• hselasky]

Does the word "mode" make sense to you?

[christos]

In D31320#705712, @hselasky wrote:

Does the word "mode" make sense to you?

"mode" is the best proposal so far indeed! :-)

[• hselasky]

OK! Can you update the patch to use "mode"?

[christos]

In D31320#705720, @hselasky wrote:

OK! Can you update the patch to use "mode"?

Done!

[christos]

Fixed flag handling.

[• hselasky]

What is the motivation for changing this?

[christos]

In D31320#705794, @hselasky wrote:

What is the motivation for changing this?

It's more consistent _both_ with the rest of the flag values in the file
(e.g SD_F_*) and with how flags are handled in userland; now we
can AND the value of mode with any of the flags. If PCM_MODE_NONE's
value is 0x00, we have to specifically check if mode == 0 too see if
PCM_MODE_NONE is set, which makes things a bit more messy --
at least in my opinion.

[• hselasky]

PCM_MODE_NONE usually means MIDI. Could you investigate that a bit?

[christos]

In D31320#705825, @hselasky wrote:

PCM_MODE_NONE usually means MIDI. Could you investigate that a bit?

Should we even have that flag in this case? If it's MIDI, is there a chance it would show up under PCM in the first place?

[• hselasky]

Yes, MIDI devices are also PCM devices, but there is no /dev/dspX device.

Let me have a look. Do you have a USB MIDI device at hand?

--HPS

[christos]

In D31320#705890, @hselasky wrote:

Yes, MIDI devices are also PCM devices, but there is no /dev/dspX device.

Let me have a look. Do you have a USB MIDI device at hand?

--HPS

Sadly no, I'm still on vacation.

[christos]

Fixed sysctl description.

[• hselasky]

sys/dev/sound/pcm/sound.c

1027

Change this into:

if (d->mixer_dev != NULL)
mode |= PCM_MODE_MIXER;

And remove PCM_MODE_NONE. It doesn't make sense to me.

sys/dev/sound/pcm/sound.h

414 ↗

(On Diff #92917)

Change PCM_MODE_NONE into PCM_MODE_MIXER

[christos]

Replaced PCM_MODE_NONE with PCM_MODE_MIXER.