Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753265AbbF2JtW (ORCPT ); Mon, 29 Jun 2015 05:49:22 -0400 Received: from cantor2.suse.de ([195.135.220.15]:41773 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752154AbbF2JtP (ORCPT ); Mon, 29 Jun 2015 05:49:15 -0400 Message-ID: <1435571292.1805.4.camel@suse.com> Subject: Re: [PATCH][RFC] usbhid: enable autosuspend for internal devices From: Oliver Neukum To: Jiri Kosina Cc: Greg Kroah-Hartman , Alan Stern , Tom Gundersen , linux-usb@vger.kernel.org, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 29 Jun 2015 11:48:12 +0200 In-Reply-To: References: <20150626221517.GB2761@kroah.com> <20150627012959.GA15207@kroah.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1419 Lines: 40 On Sat, 2015-06-27 at 08:29 +0200, Jiri Kosina wrote: > On Fri, 26 Jun 2015, Greg Kroah-Hartman wrote: > 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. What did you test? > - many keyboards were losing first keystroke when waking up from suspend. > We've been debugging this with Alan, and never root-caused it to a > problem in our code, it seems to be the property of the HW - mice don't wake up from movement alone. And again I would state that we don't get enough information from user space. Hardware seems to be designed for sleeping while a screen saver is on. In kernel space we just get a binary input desired or not desired from open/close. That is insufficient. Regards Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/