Brightness control not working (Lenovo Thinkpad T14 with integrated Intel graphics)

General support questions
Post Reply
mary_s
Posts: 1
Joined: 2021/02/08 03:59:40

Brightness control not working (Lenovo Thinkpad T14 with integrated Intel graphics)

Post by mary_s » 2021/02/08 05:11:42

Hello all,

I recently installed CentOS 7 with GNOME in a dual-boot setup with Windows 10 on my new Lenovo Thinkpad T14 with integrated Intel graphics. The control of the screen brightness does not work under CentOS and the screen is always at maximum brightness (brightness control does work under Windows though).

Some things I've already tried:

Originally the directory under /sys/class/backlight was empty, but I followed the steps outlined in https://unix.stackexchange.com/question ... s-centos-7 in order to change the boot parameters, in particular I added the

Code: Select all

thinkpad-acpi.brightness_enable=1 acpi_backlight=vendor 
parameters, and now the directory /sys/class/backlight/thinkpad_screen exists, but echo-ing a value into the brightness file in that directory does not have any effect, and the brightness slider in the settings does not have any effect either.

I installed xbacklight, but using the

Code: Select all

xbacklight -set 50
command (I tried different values) does not have any effect.

When using the command

Code: Select all

xrandr --output default --brightness 0.4
I get the output

Code: Select all

xrandr: Gamma size is 0.
but the brightness does not change.

Further info that might be relevant:

Here's the basic output of the getinfo script from the README post in this forum:

Code: Select all

== BEGIN uname -rmi ==
3.10.0-1160.el7.x86_64 x86_64 x86_64
== END   uname -rmi ==

== BEGIN rpm -qa \*-release\* ==
epel-release-7-11.noarch
centos-release-7-9.2009.0.el7.centos.x86_64
rpmfusion-free-release-7-4.noarch
== END   rpm -qa \*-release\* ==

== BEGIN cat /etc/redhat-release ==
CentOS Linux release 7.9.2009 (Core)
== END   cat /etc/redhat-release ==

== BEGIN getenforce ==
Enforcing
== END   getenforce ==

== BEGIN free -m ==
              total        used        free      shared  buff/cache   available
Mem:           7480        1915        4076         386        1487        4927
Swap:          7679           0        7679
== END   free -m ==

Here's the output of lspci -nn:

Code: Select all

00:00.0 Host bridge [0600]: Intel Corporation Device [8086:9b61] (rev 0c)
00:02.0 VGA compatible controller [0300]: Intel Corporation UHD Graphics [8086:9b41] (rev 02)
00:04.0 Signal processing controller [1180]: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem [8086:1903] (rev 0c)
00:08.0 System peripheral [0880]: Intel Corporation Xeon E3-1200 v5/v6 / E3-1500 v5 / 6th/7th/8th Gen Core Processor Gaussian Mixture Model [8086:1911]
00:12.0 Signal processing controller [1180]: Intel Corporation Comet Lake Thermal Subsytem [8086:02f9]
00:14.0 USB controller [0c03]: Intel Corporation Device [8086:02ed]
00:14.2 RAM memory [0500]: Intel Corporation Device [8086:02ef]
00:14.3 Network controller [0280]: Intel Corporation Wireless-AC 9462 [8086:02f0]
00:16.0 Communication controller [0780]: Intel Corporation Comet Lake Management Engine Interface [8086:02e0]
00:1c.0 PCI bridge [0604]: Intel Corporation Device [8086:02b8] (rev f0)
00:1c.4 PCI bridge [0604]: Intel Corporation Device [8086:02bc] (rev f0)
00:1d.0 PCI bridge [0604]: Intel Corporation Device [8086:02b0] (rev f0)
00:1d.4 PCI bridge [0604]: Intel Corporation Device [8086:02b4] (rev f0)
00:1f.0 ISA bridge [0601]: Intel Corporation Device [8086:0284]
00:1f.3 Audio device [0403]: Intel Corporation Device [8086:02c8]
00:1f.4 SMBus [0c05]: Intel Corporation Device [8086:02a3]
00:1f.5 Serial bus controller [0c80]: Intel Corporation Comet Lake SPI (flash) Controller [8086:02a4]
00:1f.6 Ethernet controller [0200]: Intel Corporation Ethernet Connection (10) I219-V [8086:0d4f]
02:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS522A PCI Express Card Reader [10ec:522a] (rev 01)
03:00.0 PCI bridge [0604]: Intel Corporation JHL6240 Thunderbolt 3 Bridge (Low Power) [Alpine Ridge LP 2016] [8086:15c0] (rev 01)
04:00.0 PCI bridge [0604]: Intel Corporation JHL6240 Thunderbolt 3 Bridge (Low Power) [Alpine Ridge LP 2016] [8086:15c0] (rev 01)
04:01.0 PCI bridge [0604]: Intel Corporation JHL6240 Thunderbolt 3 Bridge (Low Power) [Alpine Ridge LP 2016] [8086:15c0] (rev 01)
04:02.0 PCI bridge [0604]: Intel Corporation JHL6240 Thunderbolt 3 Bridge (Low Power) [Alpine Ridge LP 2016] [8086:15c0] (rev 01)
05:00.0 System peripheral [0880]: Intel Corporation JHL6240 Thunderbolt 3 NHI (Low Power) [Alpine Ridge LP 2016] [8086:15bf] (rev 01)
2b:00.0 USB controller [0c03]: Intel Corporation JHL6240 Thunderbolt 3 USB 3.1 Controller (Low Power) [Alpine Ridge LP 2016] [8086:15c1] (rev 01)
2e:00.0 Non-Volatile memory controller [0108]: Toshiba Corporation Device [1179:011a]
Here's the output of dmesg | grep thinkpad_acpi

Code: Select all

[    4.141138] thinkpad_acpi: ThinkPad ACPI Extras v0.25
[    4.141141] thinkpad_acpi: http://ibm-acpi.sf.net/
[    4.141142] thinkpad_acpi: ThinkPad BIOS N2XET23W (1.13 ), EC unknown
[    4.141143] thinkpad_acpi: Lenovo ThinkPad T14 Gen 1, model 20S00029AU
[    4.141581] thinkpad_acpi: detected a 8-level brightness capable ThinkPad
[    4.141627] thinkpad_acpi: radio switch found; radios are enabled
[    4.143456] thinkpad_acpi: rfkill switch tpacpi_bluetooth_sw: radio is unblocked
[    4.148152] input: ThinkPad Extra Buttons as /devices/platform/thinkpad_acpi/input/input9
[   26.786697] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[   26.786703] thinkpad_acpi: unhandled HKEY event 0x6032
[   26.786705] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  134.453079] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  134.453091] thinkpad_acpi: unhandled HKEY event 0x6032
[  134.453096] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  155.759848] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  155.759858] thinkpad_acpi: unhandled HKEY event 0x6032
[  155.759863] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  175.590011] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  175.590018] thinkpad_acpi: unhandled HKEY event 0x6032
[  175.590021] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  218.347273] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  218.347279] thinkpad_acpi: unhandled HKEY event 0x6032
[  218.347282] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  288.493332] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  288.493337] thinkpad_acpi: unhandled HKEY event 0x6032
[  288.493339] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  294.848520] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  294.848524] thinkpad_acpi: unhandled HKEY event 0x6032
[  294.848525] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  370.369449] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  370.369453] thinkpad_acpi: unhandled HKEY event 0x6032
[  370.369455] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  418.840234] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  418.840238] thinkpad_acpi: unhandled HKEY event 0x6032
[  418.840240] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  437.801774] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  437.801778] thinkpad_acpi: unhandled HKEY event 0x6032
[  437.801780] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  448.077467] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  448.077477] thinkpad_acpi: unhandled HKEY event 0x6032
[  448.077482] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  454.478777] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  454.478787] thinkpad_acpi: unhandled HKEY event 0x6032
[  454.478792] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  468.932399] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  468.932402] thinkpad_acpi: unhandled HKEY event 0x6032
[  468.932404] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  483.563079] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  483.563089] thinkpad_acpi: unhandled HKEY event 0x6032
[  483.563094] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  508.905406] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  508.905416] thinkpad_acpi: unhandled HKEY event 0x6032
[  508.905421] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  520.603819] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  520.603829] thinkpad_acpi: unhandled HKEY event 0x6032
[  520.603834] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  542.605701] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  542.605707] thinkpad_acpi: unhandled HKEY event 0x6032
[  542.605709] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  643.297491] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  643.297501] thinkpad_acpi: unhandled HKEY event 0x6032
[  643.297506] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  697.429294] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  697.429299] thinkpad_acpi: unhandled HKEY event 0x6032
[  697.429300] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  864.965207] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  864.965217] thinkpad_acpi: unhandled HKEY event 0x6032
[  864.965221] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  960.868976] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  960.868986] thinkpad_acpi: unhandled HKEY event 0x6032
[  960.868990] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[  971.334156] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[  971.334161] thinkpad_acpi: unhandled HKEY event 0x6032
[  971.334163] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[ 1022.900209] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[ 1022.900212] thinkpad_acpi: unhandled HKEY event 0x6032
[ 1022.900214] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[ 1066.637790] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[ 1066.637800] thinkpad_acpi: unhandled HKEY event 0x6032
[ 1066.637805] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[ 1163.846071] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[ 1163.846081] thinkpad_acpi: unhandled HKEY event 0x6032
[ 1163.846086] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[ 1189.053760] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[ 1189.053764] thinkpad_acpi: unhandled HKEY event 0x6032
[ 1189.053765] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[ 1336.234124] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[ 1336.234137] thinkpad_acpi: unhandled HKEY event 0x6032
[ 1336.234142] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[ 1455.684042] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[ 1455.684046] thinkpad_acpi: unhandled HKEY event 0x6032
[ 1455.684049] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[ 1462.709384] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[ 1462.709393] thinkpad_acpi: unhandled HKEY event 0x6032
[ 1462.709398] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
[ 1494.847830] thinkpad_acpi: unknown possible thermal alarm or keyboard event received
[ 1494.847833] thinkpad_acpi: unhandled HKEY event 0x6032
[ 1494.847834] thinkpad_acpi: please report the conditions when this event happened to ibm-acpi-devel@lists.sourceforge.net
Do you have suggestions on what I could try to get the brightness control to work?

Thanks in advance!

Post Reply

Return to “CentOS 7 - General Support”