Thread (14 messages) 14 messages, 7 authors, 2015-06-30

Re: [PATCH][RFC] usbhid: enable autosuspend for internal devices

From: Oliver Neukum <hidden>
Date: 2015-06-29 11:38:27
Also in: lkml

On Mon, 2015-06-29 at 13:16 +0200, Jiri Kosina wrote:
On Mon, 29 Jun 2015, Oliver Neukum wrote:
quoted
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).
That is the point. Unless you give the option to override, they
shouldn't autosuspend.

	Regards
		Oliver


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