diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index f0b52266b3ac..d73afb562ad9 100644
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -2124,21 +2124,29 @@ static int __init intel_opregion_present(void)
 	return opregion;
 }
 
+/* Check if the chassis-type indicates there is no builtin LCD panel */
 static bool dmi_is_desktop(void)
 {
 	const char *chassis_type;
+	unsigned long type;
 
 	chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
 	if (!chassis_type)
 		return false;
 
-	if (!strcmp(chassis_type, "3") || /*  3: Desktop */
-	    !strcmp(chassis_type, "4") || /*  4: Low Profile Desktop */
-	    !strcmp(chassis_type, "5") || /*  5: Pizza Box */
-	    !strcmp(chassis_type, "6") || /*  6: Mini Tower */
-	    !strcmp(chassis_type, "7") || /*  7: Tower */
-	    !strcmp(chassis_type, "11"))  /* 11: Main Server Chassis */
+	if (kstrtoul(chassis_type, 10, &type) != 0)
+		return false;
+
+	switch (type) {
+	case 0x03: /* Desktop */
+	case 0x04: /* Low Profile Desktop */
+	case 0x05: /* Pizza Box */
+	case 0x06: /* Mini Tower */
+	case 0x07: /* Tower */
+	case 0x10: /* Lunch Box */
+	case 0x11: /* Main Server Chassis */
 		return true;
+	}
 
 	return false;
 }
diff --git a/drivers/acpi/x86/utils.c b/drivers/acpi/x86/utils.c
index 9a8e286dd86f..c6df14802741 100644
--- a/drivers/acpi/x86/utils.c
+++ b/drivers/acpi/x86/utils.c
@@ -56,6 +56,11 @@ static const struct always_present_id always_present_ids[] = {
 	 */
 	ENTRY("80860F09", "1", ICPU(INTEL_FAM6_ATOM_SILVERMONT), {}),
 	ENTRY("80862288", "1", ICPU(INTEL_FAM6_ATOM_AIRMONT), {}),
+
+	/* Lenovo Yoga Book uses PWM2 for keyboard backlight control */
+	ENTRY("80862289", "2", ICPU(INTEL_FAM6_ATOM_AIRMONT), {
+			DMI_MATCH(DMI_PRODUCT_NAME, "Lenovo YB1-X9"),
+		}),
 	/*
 	 * The INT0002 device is necessary to clear wakeup interrupt sources
 	 * on Cherry Trail devices, without it we get nobody cared IRQ msgs.