drivers/platform/x86/thinkpad_acpi.c: Handle HKEY event 0x6040

Handle HKEY event generated on AC power change. The current message
asks users to submit data related to this event which leads to
a lot of confusion and noise on the mailing list.

The following is a list affected models and 'Message-Id'
from ibm-acpi-devel@lists.sourceforge.net of people who saw this
event when either plugging or unplugging the AC adapter or
docking or undocking their laptop.

X120e - CAAAujb5v9dHdbdxDVvhNJoG4UrZC1TgKqeB_zGpAy7q8kZHMEQ@mail.gmail.com
X121e - 20120817143459.GB3462@x1.osrc.amd.com
X220  - Confirmed by Richard Hartmann
X220i - 4F406274.7070807@gmail.com
X220t - 4F489F5B.9040705@cs.tu-berlin.de
X230  - CAKx4u7kqvVH0-gstomsiVYdGC0i6=bGxzaQ8sq9gbg76TGme3w@mail.gmail.com
T420  - 9c848ee30b006737d0534d906bab0cf6@niklaas-baudet.net
T420s - 20120608080824.GS25324@hexapodia.org
W520  - 20121008181050.GF2549@ericlaptop.home.christensenplace.us

Signed-off-by: Richard Hartmann <richih.mailinglist@gmail.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>

1 files changed, 8 insertions, 3 deletions

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 22d893654d28..be9379923a99 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -209,9 +209,8 @@ enum tpacpi_hkey_event_t {
         TP_HKEY_EV_ALARM_SENSOR_XHOT    = 0x6022, /* sensor critically hot */
         TP_HKEY_EV_THM_TABLE_CHANGED    = 0x6030, /* thermal table changed */
 
-        TP_HKEY_EV_UNK_6040             = 0x6040, /* Related to AC change?
-                                                     some sort of APM hint,
-                                                     W520 */
+        /* AC-related events */
+        TP_HKEY_EV_AC_CHANGED           = 0x6040, /* AC status changed */
 
         /* Misc */
         TP_HKEY_EV_RFKILL_CHANGED       = 0x7000, /* rfkill switch changed */
@@ -3629,6 +3628,12 @@ static bool hotkey_notify_6xxx(const u32 hkey,
                          "a sensor reports something is extremely hot!\n");
                 /* recommended action: immediate sleep/hibernate */
                 break;
+        case TP_HKEY_EV_AC_CHANGED:
+                /* X120e, X121e, X220, X220i, X220t, X230, T420, T420s, W520:
+                 * AC status changed; can be triggered by plugging or
+                 * unplugging AC adapter, docking or undocking. */
+
+                /* fallthrough */
 
         case TP_HKEY_EV_KEY_NUMLOCK:
         case TP_HKEY_EV_KEY_FN: