https://drive.google.com/file/d/1Csh3kH … share_link linux-6.1.6.arch1-3.1-x86_64.pkg.tar.zst
https://drive.google.com/file/d/1H-NFl6 … share_link linux-headers-6.1.6.arch1-3.1-x86_64.pkg.tar.zst
@cyanara are there any entries in /sys/class/backlight/ under 6.1.6 with any of the different acpi_backlight= values?
Yes, and they change depending on the values.
Using video: There's an acpi_video0 entry, the brightness buttons don't work and writing to acpi_video0/brightness does nothing.
Using vendor: There's an ideapad entry, the brightness buttons don't work and writing to ideapad/brightness does nothing.
Using native or without parameter: There's an amdgpu_bl0 entry, brightness buttons don't work, but writing to amdgpu_bl0/brightness does change the brightness.
On kernel version 6.1.3 and using acpi_backlight=video, there would be two entries (acpi_video0 and amdgpu_bl0) and everything would work.
I guess my only issue is that something made the brightness buttons stop working on 6.1.4+
I have an AMD Ryzen 5 5500U with Radeon Graphics and was using the kernel parameter acpi_backlight=video (my brightness control buttons don't work with the other options).
This worked fine up to kernel version 6.1.3, but is now broken since 6.1.4. Changing the parameter to vendor, native or removing it does not solve the issue for me.
Sadly I was only able to fix it by downgrading to 6.1.3.
]]>What happens if you boot with the option acpi_backlight=native?
Thanks, that option also fixed my old Acer 5742Z laptop with an Intel graphics chip. Now I have a /sys/classes/backlight/intel_backlight.
]]>What happens if you boot with the option acpi_backlight=native? This fixed this same issue for me on a 2012 MacBook Pro with intel graphics. I found the fix at: https://bugzilla.kernel.org/show_bug.cgi?id=216904
That matches https://bugs.archlinux.org/task/77056
Thanks guys! Replacing acpi_backlight=vendor -> native restores proper backlight operation.
Apparently, when I was testing before writing the forum post, I made a mistake.
]]>What happens if you boot with the option acpi_backlight=native? This fixed this same issue for me on a 2012 MacBook Pro with intel graphics.
That matches https://bugs.archlinux.org/task/77056
]]>What happens if you boot with the option acpi_backlight=native? This fixed this same issue for me on a 2012 MacBook Pro with intel graphics. I found the fix at: https://bugzilla.kernel.org/show_bug.cgi?id=216904
]]>What happens if you remove the acpi_backlight=vendor parameter? I remember reading some kernel devs post about potentially breaking the parameter due to rewritting the backlight handling, though I'd find it weird that an intentional change in this space would be introduced in a minor release.
On the iMac mid 2011 backlight has always worked only with acpi_backlight=vendor. If it is removed or changed to another value, backlight stops working. This happens on kernel version 6.1.3.arch1-1 or below. On kernel versions 6.1.[45].arch1-1 backlight does not work with any setting of the acpi_backlight parameter, including if it is removed...
]]>FWIW logs of 6.1.6 mention
commit 9c152189a7e85dac1f759d6ba95f877af91ccf8c
Author: Mario Limonciello <mario.limonciello@amd.com>
Date: Thu Dec 8 10:42:07 2022 -0600
ACPI: video: Don't enable fallback path for creating ACPI backlight by default
[ Upstream commit 5aa9d943e9b6bf6e6023645cbe7ce7d5ed84baf4 ]
The ACPI video detection code has a module parameter
`register_backlight_delay` which is currently configured to 8 seconds.
This means that if after 8 seconds of booting no native driver has created
a backlight device then the code will attempt to make an ACPI video
backlight device.
This was intended as a safety mechanism with the backlight overhaul that
occurred in kernel 6.1, but as it doesn't appear necesssary set it to be
disabled by default.
Suggested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@>
maybe try setting that parameter to 8 again.
]]># cat /proc/cmdline
initrd=\intel-ucode.img initrd=\initramfs-linux.img root=UUID=379486b8-e105-46b5-b271-224baff9597c rw quiet acpi_backlight=vendor
# lshw -class display
*-display
description: VGA compatible controller
product: Whistler [Radeon HD 6730M/6770M/7690M XT]
vendor: Advanced Micro Devices, Inc. [AMD/ATI]
physical id: 0
bus info: pci@0000:01:00.0
version: 00
width: 64 bits
clock: 33MHz
capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
configuration: driver=radeon latency=0
resources: irq:28 memory:90000000-9fffffff memory:a8800000-a881ffff ioport:2000(size=256) memory:a8820000-a883ffff