Commit fb1836c9 authored by Hans de Goede's avatar Hans de Goede Committed by Rafael J. Wysocki
Browse files

ACPI: video: Prefer native over vendor 



When available prefer native backlight control over vendor backlight
control.

Testing has shown that there are quite a few laptop models which rely
on native backlight control (they don't have ACPI video bus backlight
control) and on which acpi_osi_is_win8() returns false.

Currently __acpi_video_get_backlight_type() returns vendor on these
laptops, leading to an empty /sys/class/backlight.

As a workaround for this acpi_video_backlight_use_native() has been
temporarily changed to always return true.

This re-introduces the problem of having multiple backlight
devices under /sys/class/backlight for a single panel.

Change __acpi_video_get_backlight_type() to prefer native over vendor
when available. So that it returns native on these models.

And change acpi_video_backlight_use_native() back to only return
true when __acpi_video_get_backlight_type() returns native.

Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent a5df4252

drivers/acpi/video_detect.c

+3 −15
Original line number Diff line number Diff line
@@ -776,10 +776,10 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native) 
		return acpi_backlight_video;



	/* Use native if available */

	if (native_available && prefer_native_over_acpi_video())

	if (native_available)

		return acpi_backlight_native;



	/* No ACPI video (old hw), use vendor specific fw methods. */

	/* No ACPI video/native (old hw), use vendor specific fw methods. */

	return acpi_backlight_vendor;

}
@@ -791,18 +791,6 @@ EXPORT_SYMBOL(acpi_video_get_backlight_type); 


bool acpi_video_backlight_use_native(void)

{

	/*

	 * Call __acpi_video_get_backlight_type() to let it know that

	 * a native backlight is available.

	 */

	__acpi_video_get_backlight_type(true);



	/*

	 * For now just always return true. There is a whole bunch of laptop

	 * models where (video_caps & ACPI_VIDEO_BACKLIGHT) is false causing

	 * __acpi_video_get_backlight_type() to return vendor, while these

	 * models only have a native backlight control.

	 */

	return true;

	return __acpi_video_get_backlight_type(true) == acpi_backlight_native;

}

EXPORT_SYMBOL(acpi_video_backlight_use_native);