[Bug 1180591] New: Display backlight stuck at 100%
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http://bugzilla.opensuse.org/show_bug.cgi?id=1180591 Bug ID: 1180591 Summary: Display backlight stuck at 100% Classification: openSUSE Product: openSUSE Tumbleweed Version: Current Hardware: x86-64 OS: openSUSE Tumbleweed Status: NEW Severity: Normal Priority: P5 - None Component: Kernel Assignee: kernel-bugs@opensuse.org Reporter: maurizio.galli@gmail.com QA Contact: qa-bugs@suse.de Found By: --- Blocker: --- Created attachment 844855 --> http://bugzilla.opensuse.org/attachment.cgi?id=844855&action=edit system information I have just upgraded my device to Tumbleweed and now backlight brightness is stuck at 100% with no way to change it. I have tried several methods, including xbacklight and Xfce settings. Backlight control used to work fine with Kernel 5.3 shipped by Leap. I found a recent report using similar hardware that could suggest a regression in the kernel: https://discuss.getsol.us/d/6039-brightness-control-not-working-on-apple-dis... I attached information about my system but please let me know what else I can provide. -- You are receiving this mail because: You are the assignee for the bug.
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Takashi Iwai
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--- Comment #2 from Maurizio Galli
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--- Comment #3 from Maurizio Galli
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--- Comment #4 from Maurizio Galli
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--- Comment #5 from Maurizio Galli
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--- Comment #6 from Maurizio Galli
Could you give the output of hwinfo and the output of dmesg?
See attachemnts
Also, try to adjust the brightness by manually writing to sysfs files /sys/class/backlight/*/brightness. The value ranges are found in /sys/class/backlight/*/max_brightness. e.g. on my laptop, I can change it like echo -n 200 > /sys/class/backlight/intel_backlight/brightness
There might be multiple entries in /sys/class/backlight and you can try each of them.
I tried and it did not help.
And, if it used to work with Leap kernel, could you try to install the latest Leap 15.2 kernel on the current system (with zypper install --oldpackage option), boot with it and test whether the brightness works? If Leap 15.2 kernel works, give again the output of hwinfo and dmesg from it.
I still had the Leap 15.2 kernel installed and booting into allows me to change backlight. hwinfo and dmesg are attached. The issue only happens if I boot into the current TW kernel 5.10 -- You are receiving this mail because: You are the assignee for the bug.
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--- Comment #10 from Maurizio Galli
Ah, that's what I wrongly remembered, sorry.
But yes, testing with nouveau once would be interesting. This also allows testing with other older kernels more easily, too.
Switching to nouveau made no difference. The last kernel allowing me to change display backlight is 5.7. So I guess the issue is introduced in kernel 5.8. I'm attaching the dmesg and hwinfo next. -- You are receiving this mail because: You are the assignee for the bug.
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--- Comment #11 from Maurizio Galli
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--- Comment #12 from Maurizio Galli
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--- Comment #13 from Maurizio Galli
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--- Comment #14 from Maurizio Galli
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--- Comment #16 from Maurizio Galli
Thanks.
I checked briefly between v5.7 and v5.8, but there is no change in either driver/acpi/video_detect.c or drivers/acpi/acpi_video.c. So the ACPI code (in those areas) didn't change, and something else (also in ACPI) must be the cause of the regression. It's hard to tell for now.
And, I looked at the backlight support on Apple machines and they are... well... messy. There is apple-gmux driver that supports things on some devices but it's only for ACPI APP000B, which isn't enabled on yours.
At this moment, the best thing we can do is to git bisect. But of course it takes time (and patience).
It's fine if it will take time, for the time being I'll look at the screen with sunglasses on :P. Thank you for looking into it. -- You are receiving this mail because: You are the assignee for the bug.
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LAURENT LE POITTEVIN
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--- Comment #25 from LAURENT LE POITTEVIN
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--- Comment #27 from LAURENT LE POITTEVIN
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--- Comment #28 from LAURENT LE POITTEVIN
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--- Comment #29 from LAURENT LE POITTEVIN
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--- Comment #30 from LAURENT LE POITTEVIN
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--- Comment #31 from LAURENT LE POITTEVIN
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--- Comment #32 from LAURENT LE POITTEVIN
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--- Comment #33 from LAURENT LE POITTEVIN
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Marcel Kuehlhorn
It has been a while. There is a much newer kernel version in TW now. Does the issue still persist with that? It could be the case, since it looks like a problem with BIOS or ACPI.
In fact I have just recently also started seeing this issue on Tumbleweed It was still working about a week ago for me and now neither the xfce4-power-manager nor xbacklight are able to change screen brightness
# xbacklight -set 100 RANDR Query Version returned error -1
Using the method of writing to /sys with echo does work for me:
echo 378 > /sys/devices/pci0000\:00/0000\:00\:02.0/drm/card1/card1-eDP-1/intel_backlight/brightness
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--- Comment #36 from Takashi Iwai
(In reply to Miroslav Bene�� from comment #34)
It has been a while. There is a much newer kernel version in TW now. Does the issue still persist with that? It could be the case, since it looks like a problem with BIOS or ACPI.
In fact I have just recently also started seeing this issue on Tumbleweed
It was still working about a week ago for me and now neither the xfce4-power-manager nor xbacklight are able to change screen brightness
That's weird. xfce4-power-manager should access directly /sys/class/backlight stuff (via xfpm-power-backlight-helper), at least. If changing the sysfs entry directly works, it should work, too. There seems to have had some breakage and got fixed in TW about xfce4-power-manager (bsc#1202125). Could you recheck?
# xbacklight -set 100 RANDR Query Version returned error -1
If any, this must be an issue in user-space, not kernel.
Using the method of writing to /sys with echo does work for me:
echo 378 > /sys/devices/pci0000\:00/0000\:00\:02.0/drm/card1/card1-eDP-1/intel_backlight/brightness
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--- Comment #37 from Marcel Kuehlhorn
There seems to have had some breakage and got fixed in TW about xfce4-power-manager (bsc#1202125). Could you recheck?
Thanks for the pointer to the other ticket It seems that somehow pkexec was not present and was pulled in as weak dependency of gparted and gvfs-backends in todays update and the brightness control works again I'll make a SR to xfpm to add it as requirement -- You are receiving this mail because: You are the assignee for the bug.
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