linux-kernel - [PATCH] Elantech Touchpad: Fix Elantech touchpad and trackpoint for Lenovo ThinkPad notebooks.

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Date:   Fri, 28 Dec 2018 18:53:27 +0100
From:   Philipp Kaelin <kaelinphilipp@...il.com>
To:     dmitry.torokhov@...il.com
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        Philipp Kaelin <kaelinphilipp@...il.com>
Subject: [PATCH] Elantech Touchpad: Fix Elantech touchpad and trackpoint for Lenovo ThinkPad notebooks.

Initial situation:
- The touchpad of a Lenovo ThinkPad L580 doesn't work with newer kernel versions eg. 4.20
- It used to work on earlier versions eg. 4.14

Cause:
- The elantech driver was adapted in to support SMBus wich not all firmware versions
  of the elantech firmware support. The SMBus is used as default.

Solution:
- Previously a blacklist was introduced for devices which doesn't support the access using SMBus.
  The ThinkPad P52 and P72 have already been fixed by adding it to such a blacklist in a prevois patch.
  The exact same solution fixed also the issue on the mentioned ThinkPad L580.

Change:
1) The firmware id of the ThinkPad L580 was added to this blacklist.
2) To not have a half baked solution the information which firmware versions are using the same driver
   and therefore most probably have all the same issue was extracted from the Lenovo Windows driver package.
   All these firmware versions are now also added to the blacklist.

Risk assesment:
As in prevois versions of the kernel eg. 4.14 none of the devices used to be accessed via SMBus
(and they are reported to work at this time) it's quite safe that this blaklisting doesn't cause
any harm on devices which have not been testes but included in the blacklist.

Signed-off-by: Philipp Kaelin <kaelinphilipp@...il.com>
---
 drivers/input/mouse/elantech.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index 9fe075c137dc..e5fa8cfd8393 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -1772,10 +1772,25 @@ 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 */
+	"LEN2131", /* Walter-3	w/ NFC		ThinkPad P52 w/ NFC	*/
+	"LEN2132", /* Walter-3	w/o/ NFC	ThinkPad P52		*/
+	"LEN2133", /* Chiron	w/ NFC		ThinkPad P72 w/ NFC	*/
+	"LEN2134", /* Chiron	w/o/ NFC	ThinkPad P72		*/
+	"LEN2037", /* Lando	w/ NFC		ThinkPad L580 w/ NFC	*/
+	"LEN2038", /* Lando	w/o/ NFC	ThinkPad L580		*/
+	"LEN004F", /* Storm	w/o/ NFC				*/
+	"LEN005C", /* Storm	w/ NFC					*/
+	"LEN2030", /* Carling						*/
+	"LEN2031", /* Bell						*/
+	"LEN2032", /* Bell-2						*/
+	"LEN2033", /* Storm-2						*/
+	"LEN2034", /* Storm-3						*/
+	"LEN2035", /* Solo	w/ NFC					*/
+	"LEN2036", /* Solo	w/o/ NFC				*/
+	"LEN2039", /* Leia						*/
+	"LEN2130", /* Kylo	(Clamshell)				*/
+	"LEN008F", /* Kolar	w/o/ NF					*/
+	"LEN0090", /* Kolar	w/ NFC					*/
 	NULL
 };
 
-- 
2.19.2