can: c_can: Set reserved bit in IFx_MASK2 to 1 on write

commit 2bd3bc4e upstream.

According to C_CAN documentation, the reserved bit in IFx_MASK2 register is
fixed 1.
Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/net/can/c_can/c_can.c

@@ -446,8 +446,12 @@ static void c_can_setup_receive_object(struct net_device *dev, int iface,
 
 	priv->write_reg(priv, &priv->regs->ifregs[iface].mask1,
 			IFX_WRITE_LOW_16BIT(mask));
+
+	/* According to C_CAN documentation, the reserved bit
+	 * in IFx_MASK2 register is fixed 1
+	 */
 	priv->write_reg(priv, &priv->regs->ifregs[iface].mask2,
-			IFX_WRITE_HIGH_16BIT(mask));
+			IFX_WRITE_HIGH_16BIT(mask) | BIT(13));
 
 	priv->write_reg(priv, &priv->regs->ifregs[iface].arb1,
 			IFX_WRITE_LOW_16BIT(id));