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>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 39e98d216016e5e4940f414f24409a269a136c0e..a2abae124342725fe2290856bf708fa0a58bceb0 100644 (file)
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/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;