[PATCH v2 6/6] i2c: i2c-stm32f7: Implement I2C recovery mechanism

Wolfram Sang
2018-03-24T22:56:30Z

On Wed, Mar 21, 2018 at 05:49:00PM +0100, Pierre-Yves MORDRET wrote:
> Feature prevents I2C lock-ups. Mechanism resets I2C state machine
> and releases SCL/SDA signals but preserves I2C registers.
>
> Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
> ---
> Version history:
> v1:
> * Initial
> v2:
> * Don't use i2c engine recovery mechanism since driver
> procedure only recover master and not the slave.

s/recovery/release/ throughout the patch, please. Recovery is really
something else. Also, I think the dev_info's are too noisy in the log
files. I'd think the whole driver could be lifted from quite some
logging...

> ---
> ---
> drivers/i2c/busses/i2c-stm32f7.c | 27 ++++++++++++++++++++++++---
> 1 file changed, 24 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> index 91f73e0..9a9c469 100644
> --- a/drivers/i2c/busses/i2c-stm32f7.c
> +++ b/drivers/i2c/busses/i2c-stm32f7.c
> @@ -718,6 +718,20 @@ static void stm32f7_i2c_smbus_reload(struct stm32f7_i2c_dev *i2c_dev)
> writel_relaxed(cr2, i2c_dev->base + STM32F7_I2C_CR2);
> }
>
> +static int stm32f7_i2c_recover_bus(struct i2c_adapter *i2c_adap)
> +{
> + struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
> +
> + dev_info(i2c_dev->dev, "Trying to recover bus\n");
> +
> + stm32f7_i2c_clr_bits(i2c_dev->base + STM32F7_I2C_CR1,
> + STM32F7_I2C_CR1_PE);
> +
> + stm32f7_i2c_hw_config(i2c_dev);
> +
> + return 0;
> +}
> +
> static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
> {
> u32 status;
> @@ -727,12 +741,18 @@ static int stm32f7_i2c_wait_free_bus(struct stm32f7_i2c_dev *i2c_dev)
> status,
> !(status & STM32F7_I2C_ISR_BUSY),
> 10, 1000);
> + if (!ret)
> + return 0;
> +
> + dev_info(i2c_dev->dev, "bus busy\n");
> +
> + ret = stm32f7_i2c_recover_bus(&i2c_dev->adap);
> if (ret) {
> - dev_dbg(i2c_dev->dev, "bus busy\n");
> - ret = -EBUSY;
> + dev_err(i2c_dev->dev, "Failed to recover the bus (%d)\n", ret);
> + return ret;
> }
>
> - return ret;
> + return -EBUSY;
> }
>
> static void stm32f7_i2c_xfer_msg(struct stm32f7_i2c_dev *i2c_dev,
> @@ -1474,6 +1494,7 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
> if (status & STM32F7_I2C_ISR_BERR) {
> dev_err(dev, "<%s>: Bus error\n", __func__);
> writel_relaxed(STM32F7_I2C_ICR_BERRCF, base + STM32F7_I2C_ICR);
> + stm32f7_i2c_recover_bus(&i2c_dev->adap);
> f7_msg->result = -EIO;
> }
>
> --
> 2.7.4
>
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