Re: [PATCH v1 1/3] i2c: imx: only poll for bus busy in multi master mode

[Frank Li]

On Mon, Jul 15, 2024 at 05:17:51PM +0200, Stefan Eichenberger wrote:
> From: Stefan Eichenberger <stefan.eichenberger@xxxxxxxxxxx>
> 
> According to the reference manual it is only necessary to poll for bus

I supposed it should be "According to i2c spec",

> busy and arbitration lost in multi master mode. This helps to avoid
> rescheduling while the i2c bus is busy and avoids SMBus devices to
> timeout.
> 

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

> Signed-off-by: Stefan Eichenberger <stefan.eichenberger@xxxxxxxxxxx>
> ---
>  drivers/i2c/busses/i2c-imx.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 3842e527116b7..1add946e3bc20 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -216,6 +216,8 @@ struct imx_i2c_struct {
>  	struct i2c_client	*slave;
>  	enum i2c_slave_event last_slave_event;
>  
> +	bool			multi_master;
> +
>  	/* For checking slave events. */
>  	spinlock_t     slave_lock;
>  	struct hrtimer slave_timer;
> @@ -481,6 +483,9 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool a
>  	unsigned long orig_jiffies = jiffies;
>  	unsigned int temp;
>  
> +	if (!i2c_imx->multi_master)
> +		return 0;
> +
>  	while (1) {
>  		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
>  
> @@ -540,8 +545,8 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx, bool atomic)
>  		return -ETIMEDOUT;
>  	}
>  
> -	/* check for arbitration lost */
> -	if (i2c_imx->i2csr & I2SR_IAL) {
> +	/* In multi-master mode check for arbitration lost */
> +	if (i2c_imx->multi_master && (i2c_imx->i2csr & I2SR_IAL)) {
>  		dev_dbg(&i2c_imx->adapter.dev, "<%s> Arbitration lost\n", __func__);
>  		i2c_imx_clear_irq(i2c_imx, I2SR_IAL);
>  
> @@ -1468,6 +1473,8 @@ static int i2c_imx_probe(struct platform_device *pdev)
>  		goto rpm_disable;
>  	}
>  
> +	i2c_imx->multi_master = of_property_read_bool(pdev->dev.of_node, "multi-master");
> +
>  	/* Set up clock divider */
>  	i2c_imx->bitrate = I2C_MAX_STANDARD_MODE_FREQ;
>  	ret = of_property_read_u32(pdev->dev.of_node,
> -- 
> 2.43.0
>