Some touchpads don't have the "maximum number of contacts" or

"button type" usages, so assume some reasonable defaults rather than
failing to attach.

Fixes two Dell Latitude laptops and tested in snaps for a bit.

1 files changed, 17 insertions, 19 deletions

diff --git a/sys/dev/hid/hidmt.c b/sys/dev/hid/hidmt.c
index 532da1b6627..5ca26899e50 100644
--- a/sys/dev/hid/hidmt.c
+++ b/sys/dev/hid/hidmt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: hidmt.c,v 1.11 2020/02/10 14:35:08 patrick Exp $ */
+/* $OpenBSD: hidmt.c,v 1.12 2020/07/09 21:01:08 jcs Exp $ */
 /*
  * HID multitouch driver for devices conforming to Windows Precision Touchpad
  * standard
@@ -138,31 +138,29 @@ hidmt_setup(struct device *self, struct hidmt *mt, void *desc, int dlen)
 	}
 
 	/* find maximum number of contacts being reported per input report */
-	if (!hid_locate(desc, dlen, HID_USAGE2(HUP_DIGITIZERS, HUD_CONTACT_MAX),
+	mt->sc_num_contacts = HIDMT_MAX_CONTACTS;
+	if (hid_locate(desc, dlen, HID_USAGE2(HUP_DIGITIZERS, HUD_CONTACT_MAX),
 	    mt->sc_rep_cap, hid_feature, &cap, NULL)) {
-		printf("\n%s: can't find maximum contacts\n", self->dv_xname);
-		return 1;
-	}
-
-	d = hid_get_udata(rep, capsize, &cap);
-	if (d > HIDMT_MAX_CONTACTS) {
-		printf("\n%s: contacts %d > max %d\n", self->dv_xname, d,
-		    HIDMT_MAX_CONTACTS);
-		return 1;
+		d = hid_get_udata(rep, capsize, &cap);
+		if (d > HIDMT_MAX_CONTACTS)
+			printf("\n%s: contacts %d > max %d\n", self->dv_xname,
+			    d, HIDMT_MAX_CONTACTS);
+		else
+			mt->sc_num_contacts = d;
 	}
-	else
-		mt->sc_num_contacts = d;
 
 	/* find whether this is a clickpad or not */
-	if (!hid_locate(desc, dlen, HID_USAGE2(HUP_DIGITIZERS, HUD_BUTTON_TYPE),
+	if (hid_locate(desc, dlen, HID_USAGE2(HUP_DIGITIZERS, HUD_BUTTON_TYPE),
 	    mt->sc_rep_cap, hid_feature, &cap, NULL)) {
-		printf("\n%s: can't find button type\n", self->dv_xname);
-		return 1;
+		d = hid_get_udata(rep, capsize, &cap);
+		mt->sc_clickpad = (d == 0);
+	} else {
+		/* if there's not a 2nd button, this is probably a clickpad */
+		if (!hid_locate(desc, dlen, HID_USAGE2(HUP_BUTTON, 2),
+		    mt->sc_rep_input, hid_input, &cap, NULL))
+			mt->sc_clickpad = 1;
 	}
 
-	d = hid_get_udata(rep, capsize, &cap);
-	mt->sc_clickpad = (d == 0);
-
 	/*
 	 * Walk HID descriptor and store usages we care about to know what to
 	 * pluck out of input reports.