30 Aug
2011
30 Aug
'11
3:01 p.m.
Hi Clemens,
If the driver can detect ELD changes, it must inform userspace that the control has changed. If there is no ELD, the _get callback should return an error, and the control should have been set to unreadable.
Bear with my ignorance of controls, but how does the driver 'inform userspace that the control has changed'?
Or is there a way to link a control to a specify PCM device?
Yes: set .iface to _PCM instead of _MIXER (this will also prevent 'normal' mixers from showing this control, but a _BYTE control wouldn't be shown anyway), and set .device (and .subdevice, if appropriate) to the PCM device's (sub)device number.
This is exactly what I wanted, it makes things simpler. Thanks for the explanation. -Pierre