Bug 202401 - backlight control doesn't work without acpi_backlight=vendor
Summary: backlight control doesn't work without acpi_backlight=vendor
Alias: None
Product: ACPI
Classification: Unclassified
Component: Power-Video (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: Zhang Rui
Depends on:
Reported: 2019-01-24 17:28 UTC by Abderrahim Kitouni
Modified: 2019-04-01 01:33 UTC (History)
1 user (show)

See Also:
Kernel Version: 4.19.12
Regression: No
Bisected commit-id:

quirk patch (1.11 KB, patch)
2019-03-26 09:12 UTC, Zhang Rui
Details | Diff

Description Abderrahim Kitouni 2019-01-24 17:28:53 UTC
The backlight brightness control doesn't work on my Sony Vaio model VPCEH3U1E. As recommended on #nouveau I booted with acpi_backlight=vendor, and brightness control works.

Here are my system informations:
# grep '.*' /sys/class/dmi/id/*_*
/sys/class/dmi/id/board_vendor:Sony Corporation
/sys/class/dmi/id/chassis_vendor:Sony Corporation
/sys/class/dmi/id/sys_vendor:Sony Corporation

# ls /sys/class/backlight/

Setting the brightness using acpi_video0 doesn't work, but using nv_backlight works.
Comment 1 Zhang Rui 2019-03-26 09:08:07 UTC
please attach the dmidecode so that I can propose a quirk for this platform.
Comment 2 Zhang Rui 2019-03-26 09:12:40 UTC
Created attachment 282029 [details]
quirk patch

Please confirm this patch works for you.
Comment 3 Abderrahim Kitouni 2019-03-29 08:49:02 UTC
It does work indeed. Thanks.
Comment 4 Zhang Rui 2019-04-01 01:33:14 UTC
Good to know. Patch submitted at https://patchwork.kernel.org/patch/10878917/

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