Input: elantech - disable elan-i2c for P52 and P72

The current implementation of elan_i2c is known to not support those
2 laptops.

A proper fix is to tweak both elantech and elan_i2c to transmit the
correct information from PS/2, which would make a bad candidate for
stable.

So to give us some time for fixing the root of the problem, disable
elan_i2c for the devices we know are not behaving properly.

Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1803600
Link: https://bugs.archlinux.org/task/59714
Fixes: df077237cf55 Input: elantech - detect new ICs and setup Host Notify for them
Cc: stable@vger.kernel.org  # v4.18+
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index 2d95e8d93cc761aefb102217473d940faf1e4d02..9fe075c137dc41bb513060d5b69871ed922e493f 100644 (file)
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -1767,6 +1767,18 @@ static int elantech_smbus = IS_ENABLED(CONFIG_MOUSE_ELAN_I2C_SMBUS) ?
 module_param_named(elantech_smbus, elantech_smbus, int, 0644);
 MODULE_PARM_DESC(elantech_smbus, "Use a secondary bus for the Elantech device.");
 
+static const char * const i2c_blacklist_pnp_ids[] = {
+       /*
+        * These are known to not be working properly as bits are missing
+        * in elan_i2c.
+        */
+       "LEN2131", /* ThinkPad P52 w/ NFC */
+       "LEN2132", /* ThinkPad P52 */
+       "LEN2133", /* ThinkPad P72 w/ NFC */
+       "LEN2134", /* ThinkPad P72 */
+       NULL
+};
+
 static int elantech_create_smbus(struct psmouse *psmouse,
                                 struct elantech_device_info *info,
                                 bool leave_breadcrumbs)
@@ -1802,10 +1814,12 @@ static int elantech_setup_smbus(struct psmouse *psmouse,
 
        if (elantech_smbus == ELANTECH_SMBUS_NOT_SET) {
                /*
-                * New ICs are enabled by default.
+                * New ICs are enabled by default, unless mentioned in
+                * i2c_blacklist_pnp_ids.
                 * Old ICs are up to the user to decide.
                 */
-               if (!ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version))
+               if (!ETP_NEW_IC_SMBUS_HOST_NOTIFY(info->fw_version) ||
+                   psmouse_matches_pnp_id(psmouse, i2c_blacklist_pnp_ids))
                        return -ENXIO;
        }