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From:   Anson Huang <Anson.Huang@nxp.com>
To:     dmitry.torokhov@gmail.com, shawnguo@kernel.org,
        s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com,
        robh@kernel.org, linux-input@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Cc:     Linux-imx@nxp.com
Subject: [PATCH] input: keyboard: imx_sc_key: Only take the valid data from SCU firmware as key state
Date:   Fri, 13 Dec 2019 10:08:29 +0800
Message-Id: <1576202909-1661-1-git-send-email-Anson.Huang@nxp.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

When reading key state from SCU, the response data from SCU firmware
is 4 bytes due to MU message protocol, but ONLY the first byte is the
key state, other 3 bytes could be some dirty data, so we should ONLY
take the first byte as key state to avoid reporting incorrect state.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
---
 drivers/input/keyboard/imx_sc_key.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/input/keyboard/imx_sc_key.c b/drivers/input/keyboard/imx_sc_key.c
index 5379952..9f809ae 100644
--- a/drivers/input/keyboard/imx_sc_key.c
+++ b/drivers/input/keyboard/imx_sc_key.c
@@ -78,7 +78,13 @@ static void imx_sc_check_for_events(struct work_struct *work)
 		return;
 	}
 
-	state = (bool)msg.state;
+	/*
+	 * The response data from SCU firmware is 4 bytes,
+	 * but ONLY the first byte is the key state, other
+	 * 3 bytes could be some dirty data, so we should
+	 * ONLY take the first byte as key state.
+	 */
+	state = (bool)(msg.state & 0xff);
 
 	if (state ^ priv->keystate) {
 		priv->keystate = state;
-- 
2.7.4