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    Subject[PATCH 4.4 28/39] i2c: imx: Check for I2SR_IAL after every byte
    Date
    From: Christian Eggers <ceggers@arri.de>

    commit 1de67a3dee7a279ebe4d892b359fe3696938ec15 upstream.

    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>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/i2c/busses/i2c-imx.c | 10 ++++++++++
    1 file changed, 10 insertions(+)

    --- a/drivers/i2c/busses/i2c-imx.c
    +++ b/drivers/i2c/busses/i2c-imx.c
    @@ -472,6 +472,16 @@ static int i2c_imx_trx_complete(struct i
    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;

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