Some Toshibas have a broken acpi-video interface for brightness control
and need a special firmware call on resume to turn the panel back on.
So far these have been using the disable_backlight_sysfs_if workaround
to deal with this.
The recent x86/acpi backlight refactoring has broken this workaround:
1. This workaround relies on acpi_video_get_backlight_type() returning
acpi_video so that the acpi_video code actually runs; and
2. this relies on the actual native GPU driver to offer the sysfs
backlight interface to userspace.
After the refactor this breaks since the native driver will no
longer register its backlight-device if acpi_video_get_backlight_type()
does not return native and making it return native breaks 1.
Keeping the acpi_video backlight handling on resume active, while not
using it to set the brightness, is necessary because it does a _BCM
call on resume which is necessary to turn the panel back on on resume.
Looking at the DSDT shows that this _BCM call results in a Toshiba
HCI_SET HCI_LCD_BRIGHTNESS call, which turns the panel back on.
This kind of special vendor specific handling really belongs in
the vendor specific acpi driver. An earlier patch in this series
modifies toshiba_acpi to make the necessary HCI_SET call on resume
on affected models.
With toshiba_acpi taking care of the HCI_SET call on resume,
the acpi_video code no longer needs to call _BCM on resume.
So instead of using the (now broken) disable_backlight_sysfs_if
workaround, simply setting acpi_backlight=native to disable
the broken apci-video interface is sufficient fix things now.
After this there are no more users of the disable_backlight_sysfs_if
flag and as discussed above the flag also no longer works as intended,
so remove the disable_backlight_sysfs_if flag entirely.
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Arvid Norlander <lkml@vorpal.se>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
c5b94f5b78