[PATCH 4.19 14/33] Input: elantech - fix touchpad state on resume for Lenovo N24

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jonathan Denose <jdenose@google.com>

[ Upstream commit a69ce592cbe0417664bc5a075205aa75c2ec1273 ]

The Lenovo N24 on resume becomes stuck in a state where it
sends incorrect packets, causing elantech_packet_check_v4 to fail.
The only way for the device to resume sending the correct packets is for
it to be disabled and then re-enabled.

This change adds a dmi check to trigger this behavior on resume.

Signed-off-by: Jonathan Denose <jdenose@google.com>
Link: https://lore.kernel.org/r/20240503155020.v2.1.Ifa0e25ebf968d8f307f58d678036944141ab17e6@changeid
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/input/mouse/elantech.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index 6759cab82a723..6f747c59cd652 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -1527,16 +1527,47 @@ static void elantech_disconnect(struct psmouse *psmouse)
 	psmouse->private = NULL;
 }
 
+/*
+ * Some hw_version 4 models fail to properly activate absolute mode on
+ * resume without going through disable/enable cycle.
+ */
+static const struct dmi_system_id elantech_needs_reenable[] = {
+#if defined(CONFIG_DMI) && defined(CONFIG_X86)
+	{
+		/* Lenovo N24 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "81AF"),
+		},
+	},
+#endif
+	{ }
+};
+
 /*
  * Put the touchpad back into absolute mode when reconnecting
  */
 static int elantech_reconnect(struct psmouse *psmouse)
 {
+	int err;
+
 	psmouse_reset(psmouse);
 
 	if (elantech_detect(psmouse, 0))
 		return -1;
 
+	if (dmi_check_system(elantech_needs_reenable)) {
+		err = ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_DISABLE);
+		if (err)
+			psmouse_warn(psmouse, "failed to deactivate mouse on %s: %d\n",
+				     psmouse->ps2dev.serio->phys, err);
+
+		err = ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_ENABLE);
+		if (err)
+			psmouse_warn(psmouse, "failed to reactivate mouse on %s: %d\n",
+				     psmouse->ps2dev.serio->phys, err);
+	}
+
 	if (elantech_set_absolute_mode(psmouse)) {
 		psmouse_err(psmouse,
 			    "failed to put touchpad back into absolute mode.\n");
-- 
2.43.0