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Bug 266899 - media-video/nvclock-0.8_beta4-r3 sets incorrect backlight brightness
Summary: media-video/nvclock-0.8_beta4-r3 sets incorrect backlight brightness
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: AMD64 Linux
: High minor (vote)
Assignee: Jeroen Roovers (RETIRED)
Depends on:
Reported: 2009-04-20 21:24 UTC by Kasper Meerts
Modified: 2011-04-25 03:44 UTC (History)
0 users

See Also:
Package list:
Runtime testing required: ---

Write to the register correctly (nvclock.patch,533 bytes, patch)
2009-04-20 21:24 UTC, Kasper Meerts
Details | Diff
BIOS dump of NVIDIA GeForce 8400M GT (bios0.rom,64.00 KB, application/octet-stream)
2009-09-07 22:08 UTC, Kasper Meerts

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Description Kasper Meerts 2009-04-20 21:24:10 UTC
I use the nvclock program to control my LCD screen backlight.
But if I tried to set my brightness to 100% when my screen is already fully lit, e.g. after booting, the brightness decreased slightly and a low pitched whining noise is heard from the graphics card.
The nvclock program alters a register of my NVIDIA 8400M GT card with values from 0 to 1024. According to this comment from the Ubuntu launchpad, it should go to 1025, one more. Patching this makes the nvclock program work well.

I'm going to try to add a patch that solves this bug.

Reproducible: Always
Comment 1 Kasper Meerts 2009-04-20 21:24:53 UTC
Created attachment 188997 [details, diff]
Write to the register correctly
Comment 2 Jeroen Roovers (RETIRED) gentoo-dev 2009-09-07 20:06:08 UTC
Upstream thinks that it's unclear what the patch actually does since it's unknown to begin with how (why) the code really works for any unknown BIOS. As such the patch isn't exceptable even if it works for you.
Comment 3 Jeroen Roovers (RETIRED) gentoo-dev 2009-09-07 20:14:18 UTC
22:07:04  <Thunderbird> he could try to dump his video bios, it should appear
                        in ~/.nvclock and is called bios0.rom
22:07:24  <Thunderbird> if it doesn't contain bogus (I mean not just 00000 ..
                        or fffff ..) show it to me
22:11:13  <rej> I see I have that file. What triggers nvclock to do that dump?
22:11:50  <Thunderbird> any nvclock function should dump that on the first run
22:11:53  <Thunderbird> e.g. nvclock -i or so
22:13:35  <rej> ah ok

@Kasper: Could you see if your bios dump contains useful info?
Comment 4 Kasper Meerts 2009-09-07 22:08:20 UTC
Created attachment 203420 [details]
BIOS dump of NVIDIA GeForce 8400M GT
Comment 5 Kasper Meerts 2009-09-07 22:09:34 UTC
I have made an attachment with the bios dump. It looks all gibberish to me though, I'm afraid I don't understand what it means.
Comment 6 Jeroen Roovers (RETIRED) gentoo-dev 2011-01-03 12:49:35 UTC
Did you ever end up contacting Thunderbird (in irc://
Comment 7 Kasper Meerts 2011-01-03 12:57:43 UTC
(In reply to comment #6)
> Did you ever end up contacting Thunderbird (in
> irc://

Nah. The battery of my laptop broke, so it's no use trying to decrease power usage anymore. I just set brightness to its lowest at night and when I boot up my laptop in the morning, the brightness goes back to its default value.
Comment 8 Jeroen Roovers (RETIRED) gentoo-dev 2011-04-25 03:44:07 UTC
Pity we never had someone reproduce this.