Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758097AbZFMJb0 (ORCPT ); Sat, 13 Jun 2009 05:31:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754242AbZFMJbS (ORCPT ); Sat, 13 Jun 2009 05:31:18 -0400 Received: from mail-ew0-f210.google.com ([209.85.219.210]:61511 "EHLO mail-ew0-f210.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752954AbZFMJbR (ORCPT ); Sat, 13 Jun 2009 05:31:17 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=sender:message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=fXMHvc8jfCABPOx7vRH1vkFRl3Xru8DzeO01dq/Hmq8HG6AnELmOSDdDqLK6KFntVg lyDafptiKCbOqaHE1sSYbXXiU6qrqpHut2StzWNkatJzdgln/BFmjQMkuBHa2YQFsz4j hFoB3cfq2yX4xVGYKSzvyewlQOIc/V2wN7YXE= Message-ID: <4A337251.7010705@tuffmail.co.uk> Date: Sat, 13 Jun 2009 10:33:05 +0100 From: Alan Jenkins User-Agent: Mozilla-Thunderbird 2.0.0.19 (X11/20090103) MIME-Version: 1.0 To: Corentin Chary CC: Darren Salt , linux-kernel@vger.kernel.org, acpi4asus-user@lists.sourceforge.net, Matthew Garrett Subject: Re: [PATCH 2.6.29] eeepc-laptop: report brightness control events via the input layer References: <504BBE2828%linux@youmustbejoking.demon.co.uk> <20090404041813.GA30746@srcf.ucam.org> <9b2b86520906080824i134ee546v33990176b0d3e618@mail.gmail.com> <71cd59b00906130155u2757ade3t3378685846b80410@mail.gmail.com> In-Reply-To: <71cd59b00906130155u2757ade3t3378685846b80410@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4505 Lines: 109 Corentin Chary wrote: > On Mon, Jun 8, 2009 at 5:24 PM, Alan > Jenkins wrote: > >> On 4/4/09, Matthew Garrett wrote: >> >>> On Fri, Apr 03, 2009 at 06:57:50PM +0100, Darren Salt wrote: >>> >>>> This maps the brightness control events to one of two keys, either >>>> KEY_BRIGHTNESSDOWN or KEY_BRIGHTNESSUP, as needed. >>>> >>>> Some mapping has to be done due to the fact that the BIOS reports them as >>>> + ; the selection is done according >>>> to >>>> the sign of the change in brightness (if this is 0, no keypress is >>>> reported). >>>> >>>> (Ref. >>>> http://lists.alioth.debian.org/pipermail/debian-eeepc-devel/2009-April/002001.html) >>>> >>>> Signed-off-by: Darren Salt >>>> >>> The reason I didn't do this is that the Eee changes the input brightness >>> in hardware, which means reporting it via the input layer as well can >>> cause a single keypress to raise the brightness by two steps - one in >>> hardware and one triggered by userland's response to the key press. I'd >>> be a little bit wary of this causing problems. >>> >>> On the other hand, the default behaviour of the acpi video driver is to >>> change the brightness itself and then also to send the even to >>> userspace, so I guess if it was going to break things it probably would >>> have done already... >>> >> Actually, I think userspace has learnt to hack around it but it >> doesn't work perfectly. I would like to request that this change be >> reverted, or otherwise improved. >> >> Before this patch (2.6.29.4), gnome-power-manager doesn't interfere >> with the brightness keys, and they work smoothly. >> >> After this patch (2.6.30-rc7), g-p-m produces a "nice" popup in the >> middle of my tiny netbook screen. Unfortunately it can't be disabled, >> but that's not your fault :-). The brightness controls generally work >> ok. It doesn't jump two steps in response to one brightness keypress. >> But: >> >> 1) If I'm thrashing the SSD. I get jerky after-effects, where g-p-m >> seems to take too long to "catch up" with the brightness change. >> > > There is the same "lag" problem with sound :/ > Yeah :/. At it's worst, it isn't a pure "lag". It's a bit harder to explain. The firmware still changes the brightness immediately. It seems that when g-p-m gets delayed, it responds _wrongly_. It doesn't realize that the firmware already changed the brightness, so it changes the brightness again. That's why I think this is a bad "feature". User-space is working around it, but the workaround isn't reliable. I think the proper solution is that if userspace wants to respond to firmware-initiated brightness changes, it should listen for uevents on the brightness class device. You can see the problem most clearly by pressing the brightness keys in quick succession e.g. 3 times in a row, and see 3+3 brightness changes. I reproduced this with 1) 2 writers: F=1; while true do dd if=/dev/zero of=$F bs=1M count=1 conv=sync; done & F=2; while true do dd if=/dev/zero of=$F bs=1M count=1 conv=sync; done & 2) 1 reader: dd if=/dev/sda of=/dev/null 3) Drop caches before pressing the brightness keys echo 1 > /sys/proc/vm/drop_caches >> 2) If I go all the way down from full (holding down the "brightness >> down" key), and then back up a few steps. I get a noticable flash >> where the brightness looks to go up two steps, then down one. It's >> probably most noticable here because the step change between the >> lowest and the second lowest brightness is much more visible than any >> of the other steps. >> >> > I tried to install gnome-power-manager to test that, but there is no "popup". > What do I have to install to test that ? entire gnome desktop :/ ? > > Thanks > That's weird. I'm running it from KDE here (g-p-m package version 2.22.1-4 on debian stable). I'm pretty sure the only other GNOME app I have installed is Pidgin. I would know if I had much more installed, because I'm often running short of disk space :-). Maybe you have a newer version, that doesn't try to do such unreliable things? Thanks for your time Alan -- 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/