On 10/1/19 10:51 AM, Fabrice Gasnier wrote:
> When in slave mode, an arbitration loss (ARLO) may be detected before the
> slave had a chance to detect the stop condition (STOPF in ISR).
> This is seen when two master + slave adapters switch their roles. It
> provokes the i2c bus to be stuck, busy as SCL line is stretched.
> - the I2C_SLAVE_STOP event is never generated due to STOPF flag is set but
> don't generate an irq (race with ARLO irq, STOPIE is masked). STOPF flag
> remains set until next master xfer (e.g. when STOPIE irq get unmasked).
> In this case, completion is generated too early: immediately upon new
> transfer request (then it doesn't send all data).
> - Some data get stuck in TXDR register. As a consequence, the controller
> stretches the SCL line: the bus gets busy until a future master transfer
> triggers the bus busy / recovery mechanism (this can take time... and
> may never happen at all)
>
> So choice is to let the STOPF being detected by the slave isr handler,
> to properly handle this stop condition. E.g. don't mask IRQs in error
> handler, when the slave is running.
>
> Fixes: 60d609f30de2 ("i2c: i2c-stm32f7: Add slave support")
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
> ---
Hi Wolfram, all,
Gentle reminder on this patch.
Thanks in advance !
Best Regards,
Fabrice
> drivers/i2c/busses/i2c-stm32f7.c | 17 ++++++++++-------
> 1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> index 266d1c2..3a8ab0c 100644
> --- a/drivers/i2c/busses/i2c-stm32f7.c
> +++ b/drivers/i2c/busses/i2c-stm32f7.c
> @@ -1501,7 +1501,7 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
> void __iomem *base = i2c_dev->base;
> struct device *dev = i2c_dev->dev;
> struct stm32_i2c_dma *dma = i2c_dev->dma;
> - u32 mask, status;
> + u32 status;
>
> status = readl_relaxed(i2c_dev->base + STM32F7_I2C_ISR);
>
> @@ -1526,12 +1526,15 @@ static irqreturn_t stm32f7_i2c_isr_error(int irq, void *data)
> f7_msg->result = -EINVAL;
> }
>
> - /* Disable interrupts */
> - if (stm32f7_i2c_is_slave_registered(i2c_dev))
> - mask = STM32F7_I2C_XFER_IRQ_MASK;
> - else
> - mask = STM32F7_I2C_ALL_IRQ_MASK;
> - stm32f7_i2c_disable_irq(i2c_dev, mask);
> + if (!i2c_dev->slave_running) {
> + u32 mask;
> + /* Disable interrupts */
> + if (stm32f7_i2c_is_slave_registered(i2c_dev))
> + mask = STM32F7_I2C_XFER_IRQ_MASK;
> + else
> + mask = STM32F7_I2C_ALL_IRQ_MASK;
> + stm32f7_i2c_disable_irq(i2c_dev, mask);
> + }
>
> /* Disable dma */
> if (i2c_dev->use_dma) {
>
