Dne 12. 02. 21 v 13:28 Takashi Iwai napsal(a): > On Fri, 12 Feb 2021 11:32:38 +0100, > Jaroslav Kysela wrote: >> >> Dne 12. 02. 21 v 10:23 Takashi Iwai napsal(a): >>> On Thu, 11 Feb 2021 18:53:20 +0100, >>> Jaroslav Kysela wrote: >>>> >>>> Dne 11. 02. 21 v 18:15 Takashi Iwai napsal(a): >>>> >>>>>> Jaroslav Kysela (5): >>>>>> ALSA: control - introduce snd_ctl_notify_one() helper >>>>>> ALSA: control - add layer registration routines >>>>>> ALSA: control - add generic LED trigger module as the new control >>>>>> layer >>>>>> ALSA: HDA - remove the custom implementation for the audio LED trigger >>>>>> ALSA: control - add sysfs support to the LED trigger module >>>> >>>>> One thing I still miss from the picture is how to deal with the case >>>>> like AMD ACP. It has no mixer control to bundle with the LED trigger. >>>>> Your idea is to make a (dummy) user element and tie the LED trigger >>>>> with it? >>>> >>>> Yes, the user-space code which guarantee the silence stream should create an >>>> user space control with the appropriate LED group access bits. The alsa-lib's >>>> softvol PCM plugin can do this silencing for example. >>> >>> What control would it create? In the case of softvol, it's a volume >>> control that really changes the volume. For the mute LED, it's a >>> control turn on/off the mute? If so, I wonder what makes better than >>> creating it from the kernel driver. (Of course, we can list up like >>> "flexibility", etc, but it has a flip side of "complexity" and >>> "fragility"...) >> >> The current code handles both switch / volume for the marked control (assuming >> that the minimal value - usually zero - is full mute). And actually, there are >> snd_pcm_areas_silence() calls in the softvol plugin, so we know that the PCM >> stream is not passed to the application at this point. >> >> Condition: >> >> if (info.type == SNDRV_CTL_ELEM_TYPE_BOOLEAN || >> info.type == SNDRV_CTL_ELEM_TYPE_INTEGER) >> ... value.value.integer.value[i] != info.value.integer.min >> >> The softvol plugin may be extended to add the mute switch control, of course. > > Well, my question was what kind of mixer control will be added at all, > although the chip does neither volume nor mute function. Would we add > a fake volume/switch like softvol, or would we add rather a control > that is directly tied with the LED state? I don't understand your question. If the user space marks the own vol/sw control with the LED group, then it's tied with the LED state. I believe that the control should be created in the code which make sure that the PCM stream is silenced (like alsa-lib's softvol plugin). Jaroslav -- Jaroslav Kysela <perex@xxxxxxxx> Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
