This is a note to let you know that I've just added the patch titled i2c: imx: Check for I2SR_IAL after every byte to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: i2c-imx-check-for-i2sr_ial-after-every-byte.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 1de67a3dee7a279ebe4d892b359fe3696938ec15 Mon Sep 17 00:00:00 2001 From: Christian Eggers <ceggers@xxxxxxx> Date: Fri, 9 Oct 2020 13:03:19 +0200 Subject: i2c: imx: Check for I2SR_IAL after every byte From: Christian Eggers <ceggers@xxxxxxx> 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@xxxxxxx> Tested (not extensively) on Vybrid VF500 (Toradex VF50): Tested-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx> Acked-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -470,6 +470,16 @@ 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; Patches currently in stable-queue which might be from ceggers@xxxxxxx are queue-5.4/i2c-imx-check-for-i2sr_ial-after-every-byte.patch queue-5.4/i2c-imx-fix-reset-of-i2sr_ial-flag.patch queue-5.4/i2c-imx-don-t-generate-stop-condition-if-arbitration-has-been-lost.patch