Screen brightness can only be changed once on HP ZBook Fury 16 G10.
The vendor reports that the issue is related to the fact that Linux doesn't
invoke _PS0 at boot for all ACPI devices, as expected by the platform firmware:
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 ()
}
}
...
}
...
}
The \_SB.PC00.GFX0.DD1F is the panel device, and its _PS0 needs to be
executed at the initialization time to make the brightness control work
properly.
_PS0 is not evaluated for this device, because _PSC is missing,
which violates the ACPI specification (ACPI 6.5, section 7.3.6).
Commit
b3785492268f ("ACPI / PM: Do not power manage devices in unknown
initial states") tried to work around missing _PSC on platforms with
defective firmware, but got reverted due to a regression.
So the safest approach is to use acpi_device_fix_up_power_extended() to
put ACPI video and its child devices to D0 to address the issue at hand.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217683
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
if (error)
goto err_put_video;
+ /*
+ * HP ZBook Fury 16 G10 requires ACPI video's child devices have _PS0
+ * evaluated to have functional panel brightness control.
+ */
+ 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",