On Fri, Mar 23, 2018 at 12:47 AM, Takashi Iwai tiwai@suse.de wrote:
Let's follow the other usages, and here iface is set to SNDRV_CTL_ELEM_IFACE_CARD. This was for avoiding such volatile controls appearing the mixer application.
Will do - it looks like the "Clock Source Validity" control also needs this. I'll send a patch for that as well.
.access = SNDRV_CTL_ELEM_ACCESS_READ,Actually we should have set SNDRV_CTL_ELEM_ACCESS_VOLATILE, too. We forgot it in ctljack.c, too.
Sounds good.
The rest looks good. But one thing to confirm: the value change notification is done in snd_usb_mixer_interrupt()?
Also, is the jack re-detected after suspend/resume? That is, plug off the jack while sleeping, and after the resume, is the jack status change recognized and notified?
Yes - the USB audio device causes a remote wakeup, then after a few ms responds with the interrupt data message indicating the connector control that changed. This ends up calling snd_usb_mixer_interrupt().
On codeaurora kernels for Qualcomm SoCs, there's a patch which enables autosuspend for any USB device with an audio interface. https://source.codeaurora.org/quic/la/kernel/msm-4.4/tree/sound/usb/card.c?h... so suspend/resume paths are well tested when devices are used on Android.
Two new questions: #1 - I'd like to report the impedance of the load connected to the jack (generally as an integer). Is a read-only control element the right way to do this?
#2 - In our particular case there's a single jack which can detect presence of a microphone and playback separately. USB descriptors provide a mechanism to show that the input and output terminals are linked in this way (terminal type 4xx along with bAssocTerminal).
Is there a better way of having this reported than two separate mono jack controls?