1 files changed, 56 insertions, 0 deletions
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 0ca4574e89ea..4bbc8f89257f 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -1935,6 +1935,62 @@ bool acpi_dock_match(acpi_handle handle)
 	return acpi_has_method(handle, "_DCK");
 }
 
+static acpi_status
+acpi_backlight_cap_match(acpi_handle handle, u32 level, void *context,
+			  void **return_value)
+{
+	long *cap = context;
+
+	if (acpi_has_method(handle, "_BCM") &&
+	    acpi_has_method(handle, "_BCL")) {
+		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found generic backlight "
+				  "support\n"));
+		*cap |= ACPI_VIDEO_BACKLIGHT;
+		if (!acpi_has_method(handle, "_BQC"))
+			printk(KERN_WARNING FW_BUG PREFIX "No _BQC method, "
+				"cannot determine initial brightness\n");
+		/* We have backlight support, no need to scan further */
+		return AE_CTRL_TERMINATE;
+	}
+	return 0;
+}
+
+/* Returns true if the ACPI object is a video device which can be
+ * handled by video.ko.
+ * The device will get a Linux specific CID added in scan.c to
+ * identify the device as an ACPI graphics device
+ * Be aware that the graphics device may not be physically present
+ * Use acpi_video_get_capabilities() to detect general ACPI video
+ * capabilities of present cards
+ */
+long acpi_is_video_device(acpi_handle handle)
+{
+	long video_caps = 0;
+
+	/* Is this device able to support video switching ? */
+	if (acpi_has_method(handle, "_DOD") || acpi_has_method(handle, "_DOS"))
+		video_caps |= ACPI_VIDEO_OUTPUT_SWITCHING;
+
+	/* Is this device able to retrieve a video ROM ? */
+	if (acpi_has_method(handle, "_ROM"))
+		video_caps |= ACPI_VIDEO_ROM_AVAILABLE;
+
+	/* Is this device able to configure which video head to be POSTed ? */
+	if (acpi_has_method(handle, "_VPO") &&
+	    acpi_has_method(handle, "_GPD") &&
+	    acpi_has_method(handle, "_SPD"))
+		video_caps |= ACPI_VIDEO_DEVICE_POSTING;
+
+	/* Only check for backlight functionality if one of the above hit. */
+	if (video_caps)
+		acpi_walk_namespace(ACPI_TYPE_DEVICE, handle,
+				    ACPI_UINT32_MAX, acpi_backlight_cap_match, NULL,
+				    &video_caps, NULL);
+
+	return video_caps;
+}
+EXPORT_SYMBOL(acpi_is_video_device);
+
 const char *acpi_device_hid(struct acpi_device *device)
 {
 	struct acpi_hardware_id *hid;