Commit a5df4252 authored by Hans de Goede's avatar Hans de Goede Committed by Rafael J. Wysocki
Browse files

ACPI: video: Simplify __acpi_video_get_backlight_type() 



Simplify __acpi_video_get_backlight_type() removing a nested if which
makes the flow harder to follow.

This also results in having only 1 exit point with
return acpi_backlight_native instead of 2.

Note this drops the (video_caps & ACPI_VIDEO_BACKLIGHT) check from
the if (acpi_osi_is_win8() && native_available) return native path.
Windows 8's hardware certification requirements include that there must
be ACPI video bus backlight control, so the ACPI_VIDEO_BACKLIGHT check
is redundant.

Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent f5a6ff92

drivers/acpi/video_detect.c

+17 −19
Original line number Diff line number Diff line
@@ -715,6 +715,16 @@ static bool google_cros_ec_present(void) 
	return acpi_dev_found("GOOG0004") || acpi_dev_found("GOOG000C");

}



/*

 * Windows 8 and newer no longer use the ACPI video interface, so it often

 * does not work. So on win8+ systems prefer native brightness control.

 * Chromebooks should always prefer native backlight control.

 */

static bool prefer_native_over_acpi_video(void)

{

	return acpi_osi_is_win8() || google_cros_ec_present();

}



/*

 * Determine which type of backlight interface to use on this system,

 * First check cmdline, then dmi quirks, then do autodetect.
@@ -760,26 +770,14 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native) 
	if (apple_gmux_present())

		return acpi_backlight_apple_gmux;



	/* Chromebooks should always prefer native backlight control. */

	if (google_cros_ec_present() && native_available)

		return acpi_backlight_native;

	/* Use ACPI video if available, except when native should be preferred. */

	if ((video_caps & ACPI_VIDEO_BACKLIGHT) &&

	     !(native_available && prefer_native_over_acpi_video()))

		return acpi_backlight_video;



	/* On systems with ACPI video use either native or ACPI video. */

	if (video_caps & ACPI_VIDEO_BACKLIGHT) {

		/*

		 * Windows 8 and newer no longer use the ACPI video interface,

		 * so it often does not work. If the ACPI tables are written

		 * for win8 and native brightness ctl is available, use that.

		 *

		 * The native check deliberately is inside the if acpi-video

		 * block on older devices without acpi-video support native

		 * is usually not the best choice.

		 */

		if (acpi_osi_is_win8() && native_available)

	/* Use native if available */

	if (native_available && prefer_native_over_acpi_video())

		return acpi_backlight_native;

		else

			return acpi_backlight_video;

	}



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

	return acpi_backlight_vendor;