On Fri, 2 Aug 2019, Mayuresh Kulkarni wrote: > Hi Alan, > > Thanks a lot for clearing out the confusion. > > Our USB device can operate in 2 mutually exclusive modes: one is normal > composite USB audio mode and other is vendor specific HID device mode. > > On the same platform (Android based): > - When the device is in normal composite USB audio mode, > "cat /sys/bus/usb/devices/.../power/control" show "auto". > - When the device is in vendor specific HID device mode, > "cat /sys/bus/usb/devices/.../power/control" show "on". > > And hence as per your comment, I am unable to see USB-2.0 L2 for vendor > specific HID device mode. > > I guess I need to find out "who" is setting the /power/control = "auto" > when composite USB audio device is detected. And explore if it could be > moved to a more generic place. I'm pretty sure this is done by some program, not automatically done by the kernel. > Is there any module parameter (or some other means) by which, > power/control (or deprecated power/level) will always be "auto", by > default? No, there isn't. The power/control (or power/level) attribute has to be set by the user or a program. Alan Stern
