Revert "Input: elantech - enable SMBus on new (2018+) systems"

This reverts commit 883a2a80.

Apparently use dmi_get_bios_year() as manufacturing date isn't accurate
and this breaks older laptops with new BIOS update.

So let's revert this patch.

There are still new HP laptops still need to use SMBus to support all
features, but it'll be enabled via a whitelist.
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20191001070845.9720-1-kai.heng.feng@canonical.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/elantech.c

@@ -1827,31 +1827,6 @@ static int elantech_create_smbus(struct psmouse *psmouse,
 				  leave_breadcrumbs);
 }
 
-static bool elantech_use_host_notify(struct psmouse *psmouse,
-				     struct elantech_device_info *info)
-{
-	if (ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version))
-		return true;
-
-	switch (info->bus) {
-	case ETP_BUS_PS2_ONLY:
-		/* expected case */
-		break;
-	case ETP_BUS_SMB_HST_NTFY_ONLY:
-	case ETP_BUS_PS2_SMB_HST_NTFY:
-		/* SMbus implementation is stable since 2018 */
-		if (dmi_get_bios_year() >= 2018)
-			return true;
-		/* fall through */
-	default:
-		psmouse_dbg(psmouse,
-			    "Ignoring SMBus bus provider %d\n", info->bus);
-		break;
-	}
-
-	return false;
-}
-
 /**
  * elantech_setup_smbus - called once the PS/2 devices are enumerated
  * and decides to instantiate a SMBus InterTouch device.
@@ -1871,7 +1846,7 @@ static int elantech_setup_smbus(struct psmouse *psmouse,
 		 * i2c_blacklist_pnp_ids.
 		 * Old ICs are up to the user to decide.
 		 */
-		if (!elantech_use_host_notify(psmouse, info) ||
+		if (!ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version) ||
 		    psmouse_matches_pnp_id(psmouse, i2c_blacklist_pnp_ids))
 			return -ENXIO;
 	}
@@ -1891,6 +1866,34 @@ static int elantech_setup_smbus(struct psmouse *psmouse,
 	return 0;
 }
 
+static bool elantech_use_host_notify(struct psmouse *psmouse,
+				     struct elantech_device_info *info)
+{
+	if (ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version))
+		return true;
+
+	switch (info->bus) {
+	case ETP_BUS_PS2_ONLY:
+		/* expected case */
+		break;
+	case ETP_BUS_SMB_ALERT_ONLY:
+		/* fall-through  */
+	case ETP_BUS_PS2_SMB_ALERT:
+		psmouse_dbg(psmouse, "Ignoring SMBus provider through alert protocol.\n");
+		break;
+	case ETP_BUS_SMB_HST_NTFY_ONLY:
+		/* fall-through  */
+	case ETP_BUS_PS2_SMB_HST_NTFY:
+		return true;
+	default:
+		psmouse_dbg(psmouse,
+			    "Ignoring SMBus bus provider %d.\n",
+			    info->bus);
+	}
+
+	return false;
+}
+
 int elantech_init_smbus(struct psmouse *psmouse)
 {
 	struct elantech_device_info info;