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Message-ID: <71cd59b00906130306w319c0fc2i376bb03323845b80@mail.gmail.com> Date: Sat, 13 Jun 2009 12:06:18 +0200 From: Corentin Chary <corentin.chary@...il.com> To: Alan Jenkins <alan-jenkins@...fmail.co.uk> Cc: Darren Salt <linux@...mustbejoking.demon.co.uk>, linux-kernel@...r.kernel.org, acpi4asus-user@...ts.sourceforge.net, Matthew Garrett <mjg59@...f.ucam.org> Subject: Re: [PATCH 2.6.29] eeepc-laptop: report brightness control events via the input layer On Sat, Jun 13, 2009 at 11:33 AM, Alan Jenkins<alan-jenkins@...fmail.co.uk> wrote: > Corentin Chary wrote: >> >> On Mon, Jun 8, 2009 at 5:24 PM, Alan >> Jenkins<sourcejedi.lkml@...glemail.com> wrote: >> >>> >>> On 4/4/09, Matthew Garrett <mjg59@...f.ucam.org> 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 >>>>> <base value> + <current brightness index>; 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 <linux@...mustbejoking.demon.co.uk> >>>>> >>>> >>>> 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 > Hum .. running g-p-m as root, I can get the popup, strange Version: 2.24.2-2ubuntu8 Ok I can reproduce that. I want to check if we can't fix g-p-m before reverting the patch. If there is no way to fix it, I'll revert. -- Corentin Chary http://xf.iksaif.net - http://uffs.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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