Hello,

The driver for our audio hardware provides 6 snd_kcontrol_new_t structures, with their proper callbacks, members and name. One is called pmic_control_pb_vol (.name = "Master Playback Volume") in the driver, but appears somehow as "Master" in amixer and can be successfully written to using the OSS interface and ioctl as:

int mixerFd = open("/dev/mixer", O_RDWR); if (mixerFd >= 0) { unsigned int leftright; ioctl(mixerFd, SOUND_MIXER_WRITE_VOLUME, &leftright); close(mixerFd); }

It is a big enigma for me that the ioctl with the request code used above arrives automagically in the particular audio driver and calls pmic_pb_volume_put() defined in pmic_control_pb_vol.

Another control is called pmic_control_op_sw (.name = "Master Output Playback Volume") and appears in amixer as "Master Output" (in fact it is not a volume control but a switch). It is possible to set the output device using amixer. My questions are:

What is the ioctl request code for a particular snd_kcontrol_new_t defined in the driver?

Alternatively, how does the OSS layer in ALSA map the different ALSA controls to the predefined and fixed OSS controls?

The hard way (and what I am currently trying as last resort) is to write to all of them and see what happens.

Many thanks for your help, peter