linux-kernel - [PATCH 4.19 192/271] Input: alps - fix a mismatch between a condition check and its comment

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Message-Id: <20190724191711.558493338@linuxfoundation.org>
Date:   Wed, 24 Jul 2019 21:21:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hui Wang <hui.wang@...onical.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>
Subject: [PATCH 4.19 192/271] Input: alps - fix a mismatch between a condition check and its comment

From: Hui Wang <hui.wang@...onical.com>

commit 771a081e44a9baa1991ef011cc453ef425591740 upstream.

In the function alps_is_cs19_trackpoint(), we check if the param[1] is
in the 0x20~0x2f range, but the code we wrote for this checking is not
correct:
(param[1] & 0x20) does not mean param[1] is in the range of 0x20~0x2f,
it also means the param[1] is in the range of 0x30~0x3f, 0x60~0x6f...

Now fix it with a new condition checking ((param[1] & 0xf0) == 0x20).

Fixes: 7e4935ccc323 ("Input: alps - don't handle ALPS cs19 trackpoint-only device")
Cc: stable@...r.kernel.org
Signed-off-by: Hui Wang <hui.wang@...onical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/input/mouse/alps.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/input/mouse/alps.c
+++ b/drivers/input/mouse/alps.c
@@ -2879,7 +2879,7 @@ static bool alps_is_cs19_trackpoint(stru
 	 * trackpoint-only devices have their variant_ids equal
 	 * TP_VARIANT_ALPS and their firmware_ids are in 0x20~0x2f range.
 	 */
-	return param[0] == TP_VARIANT_ALPS && (param[1] & 0x20);
+	return param[0] == TP_VARIANT_ALPS && ((param[1] & 0xf0) == 0x20);
 }
 
 static int alps_identify(struct psmouse *psmouse, struct alps_data *priv)