i2c: imx: Check for I2SR_IAL after every byte

Arbitration Lost (IAL) can happen after every single byte transfer. If
arbitration is lost, the I2C hardware will autonomously switch from
master mode to slave. If a transfer is not aborted in this state,
consecutive transfers will not be executed by the hardware and will
timeout.
Signed-off-by: Christian Eggers <ceggers@arri.de>
Tested (not extensively) on Vybrid VF500 (Toradex VF50):
Tested-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-imx.c

@@ -490,6 +490,16 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx, bool atomic)
 		dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
 		return -ETIMEDOUT;
 	}
+
+	/* check for arbitration lost */
+	if (i2c_imx->i2csr & I2SR_IAL) {
+		dev_dbg(&i2c_imx->adapter.dev, "<%s> Arbitration lost\n", __func__);
+		i2c_imx_clear_irq(i2c_imx, I2SR_IAL);
+
+		i2c_imx->i2csr = 0;
+		return -EAGAIN;
+	}
+
 	dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__);
 	i2c_imx->i2csr = 0;
 	return 0;