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 --- Hi Greg,

here is the patch for linux-5.4. Please let me know if this doesn't apply to older kernels.

regards Christian

On Wednesday, 9 December 2020, 09:33:00 CET, gregkh@linuxfoundation.org wrote:

The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1de67a3dee7a279ebe4d892b359fe3696938ec15 Mon Sep 17 00:00:00 2001

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

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index bba612cf775d..9d3f42fd6352 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -470,6 +470,16 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx) 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;