linux-kernel - [055/143] Input: elantech

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Date:	Thu, 05 May 2011 17:20:40 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Dmitry Torokhov <dtor@...l.ru>
Subject: [055/143] Input: elantech - relax signature checks

2.6.32-longterm review patch.  If anyone has any objections, please let us know.

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

From: Dmitry Torokhov <dmitry.torokhov@...il.com>

commit a083632eaf6231162b33e40561cfec6a9c156945 upstream.

Apparently there are Elantech touchpads that report non-zero in the 2nd byte
of their signature. Adjust the detection routine so that if 2nd byte is
zero and 3rd byte contains value that is not a valid report rate, we still
assume that signature is valid.

Tested-by: Eric Piel <eric.piel@...mplin-utc.net>
Signed-off-by: Dmitry Torokhov <dtor@...l.ru>
[bwh: Adjust context for 2.6.32]
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 drivers/input/mouse/elantech.c |   20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -574,6 +574,24 @@ static struct attribute_group elantech_a
 	.attrs = elantech_attrs,
 };
 
+static bool elantech_is_signature_valid(const unsigned char *param)
+{
+	static const unsigned char rates[] = { 200, 100, 80, 60, 40, 20, 10 };
+	int i;
+
+	if (param[0] == 0)
+		return false;
+
+	if (param[1] == 0)
+		return true;
+
+	for (i = 0; i < ARRAY_SIZE(rates); i++)
+		if (param[2] == rates[i])
+			return false;
+
+	return true;
+}
+
 /*
  * Use magic knock to detect Elantech touchpad
  */
@@ -617,7 +635,7 @@ int elantech_detect(struct psmouse *psmo
 	pr_debug("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) {
+	if (!elantech_is_signature_valid(param)) {
 		if (!force_elantech) {
 			pr_debug("elantech.c: Probably not a real Elantech touchpad. Aborting.\n");
 			return -1;


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