Red Hat Bugzilla – Bug 529859
Screen is fairly dim, even at 100% brightness
Last modified: 2015-01-07 19:16:50 EST
Description of problem:
I'm not entirely sure this is a driver problem, but reporting it as that seems the best starting place. With both xorg-x11-drv-nouveau-0.0.15-2.20090805git712064e.fc12 and a live image that jlaska provided on 20.10.2009, the screen on my Sony Vaio VGN-AW230J laptop is fairly dim. Whether on battery of AC, I'm not able to get the screen brightness more than what I would consider is about 60%, even though both the hardware control and the slider in the power configuration are set to 100%.
Version-Release number of selected component (if applicable):
The obvious question first is, what makes you think the screen *can* go brighter? :)
Anyway, not really sure where to start with this exactly. But, can you show me the values of the various files in /sys/class/backlight? There should be at least an nv_backlight if nouveau's loaded, at least on this chipset.
The other useful bit of info to know would be how the VBIOS initialises the backlight, on most (as in, all i've seen) it'll initialise the backlight to its maximum when it POSTs the card. So, can you boot with "drm.debug=15 3" and save the output of the "dmesg" command. Hopefully that portion of the init process will survive in the log buffer.
Guess I should have specified that in the initial report. Prior to installing RHEL6 on the machine Monday (19.10.2009) it was running RHEL5.3 and the screen was significantly brighter there running the 'nv' driver.
As for the files, here are the values . . . there are lots of circular links in that tree, so let me know if I'm missing a value you are particularly interested in seeing:
The above data is after ensuring that the hardware brightness controls are as high as they will go (<fcnt>-brightness keys,) the laptop is plugged into AC power and the power management preferences are set to 100% brightness.
I'm gathering the drm.debug data right now and will post it.
Created attachment 365486 [details]
dmesg output from booting with 'drm.debug 15 3'
Another data-point. I also have an Lenovo W700 with an nVidia NV92 running the same code but not exhibiting the same dimness issues. Some notes:
- Even with both the power management and hardware controls set up full on my Vaio, I can't get any higher than 974 for actual_brightness. I'm able to get 1025 on the Lenovo.
- On the Lenovo, setting the power management slider to 0% or toggling the hardware control to 0 still leaves me with a viewable display, albeit dim. Toggling my Vaio to 0% results in a completely black display.
jlaska recommended that I try with "nomodeset" and sure enough, that yields a much brighter screen. Granted the values of /sys/class/backlight are identical, but the screen is noticeably brighter!
Created attachment 367131 [details]
Xorg.0.log from 'nomodeset' boot
Since this bugzilla report was filed, there have been several major updates in various components of the Xorg system, which may have resolved this issue. Users who have experienced this problem are encouraged to upgrade their system to the latest version of their packages (at least F12Beta, but even better if the very latest versions).
Please, if you experience this problem on the up-to-date system, let us now in the comment for this bug, or whether the upgraded system works for you.
If you won't be able to reply in one month, I will have to close this bug as INSUFFICIENT_DATA. Thank you.
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Booted up a live Fedora image created from last night's tree (4.11.2009) and am still seeing the same issues with the dim screen. Also, as with RHEL, booting the system with "nomodeset" nets a much brighter display.
This bug appears to have been reported against 'rawhide' during the Fedora 12 development cycle.
Changing version to '12'.
More information and reason for this action is here:
While investigating another bug, I came across something which could also be the culprit here, perhaps.
Can you boot with (try each in turn until one, if any, works):
Both options result in a message about being unsupported boot options, but then appear to have an effect so I'm guessing the warning is a bit off. 0x0200 results in a kernel panic, but I wasn't able to capture any details. 0x0300, however, makes my laptop all happy! I have a nice, bright screen again. I'll test out to make sure I can still suspect and whatnot, but appears this might be the magic bullet.
Thanks! The kernel panic is odd, at worst I'd have expected no/bad display. Good to hear 0x0300 works however, now the problem is detecting *when* we need to use it so you don't need to override nouveau's default choice.
I'll keep looking into it, fairly big issue, there's at least 2 other known cases now where this is needed.
Are you able to send me a VBIOS image too please? It'll help with tracking down exactly what's needed to do this automatically. Instructions for dumping the VBIOS are at: http://nouveau.freedesktop.org/wiki/DumpingVideoBios
Created attachment 375059 [details]
VBIOS from nVidia GeForce 9600M GT
I went back and tried 0x0200 again and I think the kernel panic might have been completely unrelated. That having been said, 0x0200 causes these colored bars to appear on the display. Some are wide, some are narrow and the effect is like looking at the results of a spectrometer.
kernel-126.96.36.199-158.fc12 (http://koji.fedoraproject.org/koji/buildinfo?buildID=143969) will hopefully fix the issue, and not require special options to be set.
As a data point, just booted up 2.6.32-2.el6 (+ patch to work about signing problem; bug 548027) and without the nouveau.uscript_lvds=0x0300 argument, the screen is back to being dim. I added the argument again and the screen is back to normal. Also appears that it is time to clone this over to a RHEL bug.
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