---

yaml
---
r: 154187
b: refs/heads/master
c: d7880f1
h: refs/heads/master
i:
  154185: 488767f
  154183: 9c33d6d
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8bf3d4c535c2b9689c2979b281c24e9f59c2f4ad
+refs/heads/master: d7880f10c5d42ba182a97c1fd41d41d0b8837097

trunk/Documentation/laptops/thinkpad-acpi.txt

@@ -1169,17 +1169,19 @@ may not be distinct.  Later Lenovo models that implement the ACPI
 display backlight brightness control methods have 16 levels, ranging
 from 0 to 15.
 
-There are two interfaces to the firmware for direct brightness control,
-EC and UCMS (or CMOS).  To select which one should be used, use the
-brightness_mode module parameter: brightness_mode=1 selects EC mode,
-brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
-mode with NVRAM backing (so that brightness changes are remembered
-across shutdown/reboot).
+For IBM ThinkPads, there are two interfaces to the firmware for direct
+brightness control, EC and UCMS (or CMOS).  To select which one should be
+used, use the brightness_mode module parameter: brightness_mode=1 selects
+EC mode, brightness_mode=2 selects UCMS mode, brightness_mode=3 selects EC
+mode with NVRAM backing (so that brightness changes are remembered across
+shutdown/reboot).
 
 The driver tries to select which interface to use from a table of
 defaults for each ThinkPad model.  If it makes a wrong choice, please
 report this as a bug, so that we can fix it.
 
+Lenovo ThinkPads only support brightness_mode=2 (UCMS).
+
 When display backlight brightness controls are available through the
 standard ACPI interface, it is best to use it instead of this direct
 ThinkPad-specific interface.  The driver will disable its native

trunk/drivers/platform/x86/thinkpad_acpi.c

@@ -5696,6 +5696,10 @@ static struct ibm_struct ecdump_driver_data = {
  *   Bit 3-0: backlight brightness level
  *
  * brightness_get_raw returns status data in the HBRV layout
+ *
+ * WARNING: The X61 has been verified to use HBRV for something else, so
+ * this should be used _only_ on IBM ThinkPads, and maybe with some careful
+ * testing on the very early *60 Lenovo models...
  */
 
 enum {
@@ -5996,6 +6000,12 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 			   brightness_mode);
 	}
 
+	/* Safety */
+	if (thinkpad_id.vendor != PCI_VENDOR_ID_IBM &&
+	    (brightness_mode == TPACPI_BRGHT_MODE_ECNVRAM ||
+	     brightness_mode == TPACPI_BRGHT_MODE_EC))
+		return -EINVAL;
+
 	if (tpacpi_brightness_get_raw(&b) < 0)
 		return 1;