1. Work around a firmware bug of some Elantech-v1 touchpads.

2. Remove obsolete code from the v1-/v2-packet handlers (coordinate
values are ignored if z is 0).

1 files changed, 20 insertions, 7 deletions

diff --git a/sys/dev/pckbc/pms.c b/sys/dev/pckbc/pms.c
index 0ee104d6be2..360ec47115c 100644
--- a/sys/dev/pckbc/pms.c
+++ b/sys/dev/pckbc/pms.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: pms.c,v 1.94 2020/08/10 21:55:59 mglocker Exp $ */
+/* $OpenBSD: pms.c,v 1.95 2020/10/23 22:06:27 bru Exp $ */
 /* $NetBSD: psm.c,v 1.11 2000/06/05 22:20:57 sommerfeld Exp $ */
 
 /*-
@@ -142,6 +142,7 @@ struct elantech_softc {
 
 	int max_x, max_y;
 	int old_x, old_y;
+	int initial_pkt;
 };
 #define ELANTECH_IS_CLICKPAD(sc) (((sc)->elantech->fw_version & 0x1000) != 0)
 
@@ -2443,15 +2444,29 @@ pms_proc_elantech_v1(struct pms_softc *sc)
 	else
 		w = (sc->packet[0] & 0xc0) >> 6;
 
+	/*
+	 * Firmwares 0x20022 and 0x20600 have a bug, position data in the
+	 * first two reports for single-touch contacts may be corrupt.
+	 */
+	if (elantech->fw_version == 0x20022 ||
+	    elantech->fw_version == 0x20600) {
+		if (w == 1) {
+			if (elantech->initial_pkt < 2) {
+				elantech->initial_pkt++;
+				return;
+			}
+		} else if (elantech->initial_pkt) {
+			elantech->initial_pkt = 0;
+		}
+	}
+
 	/* Hardware version 1 doesn't report pressure. */
 	if (w) {
 		x = ((sc->packet[1] & 0x0c) << 6) | sc->packet[2];
 		y = ((sc->packet[1] & 0x03) << 8) | sc->packet[3];
 		z = SYNAPTICS_PRESSURE;
 	} else {
-		x = elantech->old_x;
-		y = elantech->old_y;
-		z = 0;
+		x = y = z = 0;
 	}
 
 	WSMOUSE_TOUCH(sc->sc_wsmousedev, buttons, x, y, z, w);
@@ -2488,9 +2503,7 @@ pms_proc_elantech_v2(struct pms_softc *sc)
 		y = (((sc->packet[0] & 0x20) << 3) | sc->packet[2]) << 2;
 		z = SYNAPTICS_PRESSURE;
 	} else {
-		x = elantech->old_x;
-		y = elantech->old_y;
-		z = 0;
+		x = y = z = 0;
 	}
 
 	WSMOUSE_TOUCH(sc->sc_wsmousedev, buttons, x, y, z, w);