https://bugzilla.kernel.org/show_bug.cgi?id=204251
Bug ID: 204251
Summary: intel_backlight brightness ACPI BIOS Error (bug) on
Dell Precision 5540 (CoffeeLake)
Product: ACPI
Version: 2.5
Kernel Version: 5.1.18-300.fc30.x86_64
Hardware: Intel
OS: Linux
Tree: Mainline
Status: NEW
Severity: high
Priority: P1
Component: BIOS
Assignee: acpi_b...@kernel-bugs.osdl.org
Reporter: arca...@ivanov.biz
Regression: No
It's completely impossible to change the backlight brightness on Dell Precision
5540. The intel_backlight driver seems to be working correctly, however the
ACPI BIOS seems to be broken. While the brightness values do change, the actual
backlight brightness is unaffected except to turn the screen completely off.
Example:
$ pwd
/sys/class/backlight/intel_backlight
$ ls -la
total 0
drwxr-xr-x 3 root root 0 Jul 21 00:29 .
drwxr-xr-x 6 root root 0 Jul 21 00:29 ..
-r--r--r-- 1 root root 4096 Jul 21 00:29 actual_brightness
-rw-r--r-- 1 root root 4096 Jul 21 00:29 bl_power
-rw-rw-rw- 1 root root 4096 Jul 20 16:50 brightness
lrwxrwxrwx 1 root root 0 Jul 21 00:29 device -> ../../card0-eDP-1
-r--r--r-- 1 root root 4096 Jul 21 00:29 max_brightness
drwxr-xr-x 2 root root 0 Jul 21 00:29 power
lrwxrwxrwx 1 root root 0 Jul 21 00:29 subsystem ->
../../../../../../../class/backlight
-r--r--r-- 1 root root 4096 Jul 21 00:29 type
-rw-r--r-- 1 root root 4096 Jul 21 00:29 uevent
$ echo $(cat brightness) $(cat actual_brightness) $(cat max_brightness)
65535 65535 65535
[28007.115439] ACPI BIOS Error (bug): Could not resolve symbol
[\_SB.PCI0.PEG0.PEGP.BRT6.LCD], AE_NOT_FOUND (20190215/psargs-330)
[28007.115463] ACPI Error: Aborting method \_SB.PCI0.PEG0.PEGP.BRT6 due to
previous error (AE_NOT_FOUND) (20190215/psparse-529)
[28007.115851] ACPI Error: Aborting method \EV5 due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28007.116101] ACPI Error: Aborting method \SMEE due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28007.116249] ACPI Error: Aborting method \SMIE due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28007.116391] ACPI Error: Aborting method \NEVT due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28007.116528] ACPI Error: Aborting method \_SB.PCI0.LPCB.ECDV._Q66 due to
previous error (AE_NOT_FOUND) (20190215/psparse-529)
$ echo $(cat brightness) $(cat actual_brightness) $(cat max_brightness)
62258 62258 65535
[28012.948074] ACPI BIOS Error (bug): Could not resolve symbol
[\_SB.PCI0.PEG0.PEGP.BRT6.LCD], AE_NOT_FOUND (20190215/psargs-330)
[28012.948098] ACPI Error: Aborting method \_SB.PCI0.PEG0.PEGP.BRT6 due to
previous error (AE_NOT_FOUND) (20190215/psparse-529)
[28012.948251] ACPI Error: Aborting method \EV5 due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28012.948387] ACPI Error: Aborting method \SMEE due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28012.948515] ACPI Error: Aborting method \SMIE due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28012.948642] ACPI Error: Aborting method \NEVT due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28012.948770] ACPI Error: Aborting method \_SB.PCI0.LPCB.ECDV._Q66 due to
previous error (AE_NOT_FOUND) (20190215/psparse-529)
$ echo $(cat brightness) $(cat actual_brightness) $(cat max_brightness)
58982 58982 65535
[28016.564461] ACPI BIOS Error (bug): Could not resolve symbol
[\_SB.PCI0.PEG0.PEGP.BRT6.LCD], AE_NOT_FOUND (20190215/psargs-330)
[28016.564481] ACPI Error: Aborting method \_SB.PCI0.PEG0.PEGP.BRT6 due to
previous error (AE_NOT_FOUND) (20190215/psparse-529)
[28016.564781] ACPI Error: Aborting method \EV5 due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28016.565136] ACPI Error: Aborting method \SMEE due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28016.565378] ACPI Error: Aborting method \SMIE due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28016.565804] ACPI Error: Aborting method \NEVT due to previous error
(AE_NOT_FOUND) (20190215/psparse-529)
[28016.566054] ACPI Error: Aborting method \_SB.PCI0.LPCB.ECDV._Q66 due to
previous error (AE_NOT_FOUND) (20190215/psparse-529)
$ echo $(cat brightness) $(cat actual_brightness) $(cat max_brightness)
55705 55705 65535
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