Ubuntu
linux-lts-trusty package

  1. Bug #1416940
  2. Comment #4

Comment 4 for bug 1416940

Revision history for this message
Alex Hung (alexhung) wrote :

This is related to the OS detection in _BCM control method in DSDT; however, this is a system from 2012 and it is not likely have any BIOS update from this.

There are two possible solutions -

1. add a quirk in drivers/acpi/blacklist.c such as below:

+ {
+ .callback = dmi_disable_osi_win8,
+ .ident = "HP Pavilion dv6",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "HP Pavilion dv6 Notebook PC"),
+ },
+ },

This is tested and it works well.

2. newer version of linux kernel enable "use_native_backlight" by default. This remove ACPI video brightness out of picture and therefore _BCM will not be used.

This is tested with mainline kernel @ http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.19-vivid/