linux-kernel - Re: 2.6.28 thinks that my PS/2 mouse is a touchpad

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Date:	Fri, 2 Jan 2009 19:37:14 +0100
From:	Arjan Opmeer <arjan@...eer.net>
To:	Denys Vlasenko <vda.linux@...glemail.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	"Alexander E. Patrakov" <patrakov@...il.com>,
	linux-kernel@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: 2.6.28 thinks that my PS/2 mouse is a touchpad

On Fri, Jan 02, 2009 at 01:07:54AM +0100, Denys Vlasenko wrote:
> On Monday 29 December 2008 19:56, Arjan Opmeer wrote:
> > On Sat, Dec 27, 2008 at 02:06:29PM +0500, Alexander E. Patrakov wrote:
> > > 
> > > Linux-2.6.28, as compiled by Arch Linux developers, thinks that my
> > > PS/2 mouse (a cheap M-BT58 optical wheel mouse by Logitech) is
> > > actually a touchpad.  This makes it unusable.  Adding the "proto=imps"
> > > parameter to the psmouse module helps.
> > 
> > > CONFIG_MOUSE_PS2_ELANTECH=y
> > 
> > Oh dear. The first victim of this driver... :(
> > 
> > As we can see below the mouse gets detected as an Elantech touchpad.
> > This means that it reacts to the Elantech magic knock with the exact
> > same response we expect from a real Elantech touchpad.
> 
> I am affected too. I am getting:
> 
> input: AT Translated Set 2 keyboard as /class/input/input2
> elantech.c: Elantech version query result 0x00, 0x01, 0x64.
> elantech.c: assuming hardware version 1, firmware version 0.100
> elantech.c: Synaptics capabilities query result 0x00, 0x02, 0x64.
> input: ETPS/2 Elantech Touchpad as /class/input/input3

So how about we try to solve it by duplicating the version query in
elantech_detect() and check for sane values. Dmitry, do you think something
like this would be acceptable?


Arjan

--- elantech.c.ORIG	2008-12-29 19:35:01.000000000 +0100
+++ elantech.c.NEW2	2009-01-02 19:26:01.000000000 +0100
@@ -556,6 +556,22 @@ int elantech_detect(struct psmouse *psmo
 		return -1;
 	}
 
+	/*
+	 * There are Logitech mice that react to the magic knock exactly
+	 * like an Elantech touchpad would, so do a version query here to
+	 * try to distinguish the two
+	 */
+	if (synaptics_send_cmd(psmouse, ETP_FW_VERSION_QUERY, param)) {
+		pr_err("elantech.c: failed to query firmware version.\n");
+		return -1;
+	}
+	pr_info("elantech.c: Elantech version query result 0x%02x, 0x%02x, 0x%02x.\n",
+		param[0], param[1], param[2]);
+	if (param[0] == 0 || param[1] != 0) {
+		pr_info("elantech.c: Probably not a real Elantech touchpad. Aborting.\n");
+		return -1;
+	}
+
 	if (set_properties) {
 		psmouse->vendor = "Elantech";
 		psmouse->name = "Touchpad";
@@ -610,14 +626,12 @@ int elantech_init(struct psmouse *psmous
 		etd->parity[i] = etd->parity[i & (i - 1)] ^ 1;
 
 	/*
-	 * Find out what version hardware this is
+	 * Do the version query again so we can store the result
 	 */
 	if (synaptics_send_cmd(psmouse, ETP_FW_VERSION_QUERY, param)) {
 		pr_err("elantech.c: failed to query firmware version.\n");
 		goto init_fail;
 	}
-	pr_info("elantech.c: Elantech version query result 0x%02x, 0x%02x, 0x%02x.\n",
-		param[0], param[1], param[2]);
 	etd->fw_version_maj = param[0];
 	etd->fw_version_min = param[2];
 
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