[PATCH stable 5.2/4.19] Revert "Input: elantech - enable SMBus on new (2018+) systems"

[Benjamin Tissoires]

This reverts commit 60956b018bfe23b879405a7d88103d0a8f06a5e3.

This patch depends on an other series:
https://patchwork.kernel.org/project/linux-input/list/?series=122327&state=%2A&archive=both

It was a mistake to backport it in the v5.2 branch, as there
is a high chance we encounter a touchpad that needs the series
above.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=204733
Link: https://bugzilla.kernel.org/show_bug.cgi?id=204771
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>

---

Hi,

this is a stable only patch aimed at kernels v5.2 and v4.19 branches.

We already have 2 bug reports of a failing touchpad, and I don't think
it is worth trying to get a smoother touchpad if we randomly
break a few of them in the way.

Cheers,
Benjamin
---
 drivers/input/mouse/elantech.c | 54 ++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 25 deletions(-)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index a47c7add4e0e..a4345052abd2 100644
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -1807,30 +1807,6 @@ 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;
-	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.
@@ -1850,7 +1826,7 @@ 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;
 	}
@@ -1870,6 +1846,34 @@ 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;
-- 
2.21.0