On Mon, 29 Jun 2015, Oliver Neukum wrote:

quoted

Last time we were testing this, autosuspend for USB HID devices was quite 
a disaster.

Do you have any idea whether udev developers tested the "autosuspend on by 
default for USB HID devices" on reasonable set of devices?

The culrpits that I remember from top of my head (it's been long time 
ago):

- the LEDs for suspended device go off. This is very confusing at least on 
  keyboards, and brings really bad user experience

That is a bug. hidinput_count_leds() is supposed to prevent that.

This is a HW property and nothing kernel can do about. I am not saying it 
doesn't bring the LEDs up to a proper state again once auto-resumed. But I 
hate the LEDs going off a few seconds after I stop typing (i.e. once the 
keyboard gets auto-suspended).

-- 
Jiri Kosina
SUSE Labs