Screen brightness can only be changed once on some HP laptops. Vendor identified the root cause as Linux doesn't invoke _PS0 at boot for all ACPI devices: Scope (\_SB.PC00.GFX0) { Scope (DD1F) { Method (_PS0, 0, Serialized) // _PS0: Power State 0 { If (CondRefOf (\_SB.PC00.LPCB.EC0.SSBC)) { \_SB.PC00.LPCB.EC0.SSBC () } } ... } ... } _PS0 doesn't get invoked for all ACPI devices because of commit 7cd8407d53ef ("ACPI / PM: Do not execute _PS0 for devices without _PSC during initialization"). For now explicitly call _PS0 for ACPI video to workaround the issue. Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx> --- drivers/acpi/acpi_video.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c index 62f4364e4460..793259bd18c8 100644 --- a/drivers/acpi/acpi_video.c +++ b/drivers/acpi/acpi_video.c @@ -2027,6 +2027,8 @@ static int acpi_video_bus_add(struct acpi_device *device) if (error) goto err_put_video; + acpi_device_fix_up_power_extended(device); + pr_info("%s [%s] (multi-head: %s rom: %s post: %s)\n", ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device), video->flags.multihead ? "yes" : "no", -- 2.34.1