[PATCH 3.16.y-ckt 032/144] Input: synaptics - do not retrieve the board id on old firmwares

[Luis Henriques]

3.16.7-ckt10 -stable review patch.  If anyone has any objections, please let me know.

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

From: Benjamin Tissoires <benjamin.tissoires at redhat.com>

commit b57a7128be24062b5b5b26032b7cd58f1651547e upstream.

The board id capability has been added in firmware 7.5.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires at redhat.com>
Acked-by: Hans de Goede <hdegoede at redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov at gmail.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/input/mouse/synaptics.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index 367a9457547d..6d04d199b6be 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -248,6 +248,10 @@ static int synaptics_board_id(struct psmouse *psmouse)
 	struct synaptics_data *priv = psmouse->private;
 	unsigned char bid[3];
 
+	/* firmwares prior 7.5 have no board_id encoded */
+	if (SYN_ID_FULL(priv->identity) < 0x705)
+		return 0;
+
 	if (synaptics_send_cmd(psmouse, SYN_QUE_MODES, bid))
 		return -1;
 	priv->board_id = ((bid[0] & 0xfc) << 6) | bid[1];