Re: [PATCH V2 2/7] i2c: sprd: Add I2C driver to use 'reset framework' function

[Baolin Wang]

On 10/23/2023 4:11 PM, Huangzheng Lai wrote:
> Add the 'reset framework' function for I2C drivers, which
> resets the I2C controller when a timeout exception occurs.

Can you explain the situations that can lead to a timeout explicitly?

> Signed-off-by: Huangzheng Lai <Huangzheng.Lai@xxxxxxxxxx>
> ---
>   drivers/i2c/busses/i2c-sprd.c | 19 +++++++++++++++++--
>   1 file changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c
> index b44916c6741d..aa602958d4fd 100644
> --- a/drivers/i2c/busses/i2c-sprd.c
> +++ b/drivers/i2c/busses/i2c-sprd.c
> @@ -17,6 +17,7 @@
>   #include <linux/of_device.h>
>   #include <linux/platform_device.h>
>   #include <linux/pm_runtime.h>
> +#include <linux/reset.h>
>   
>   #define I2C_CTL			0x00
>   #define I2C_ADDR_CFG		0x04
> @@ -85,6 +86,7 @@ struct sprd_i2c {
>   	u32 src_clk;
>   	u32 bus_freq;
>   	struct completion complete;
> +	struct reset_control *rst;
>   	u8 *buf;
>   	u32 count;
>   	int irq;
> @@ -278,9 +280,17 @@ static int sprd_i2c_handle_msg(struct i2c_adapter *i2c_adap,
>   
>   	time_left = wait_for_completion_timeout(&i2c_dev->complete,
>   				msecs_to_jiffies(I2C_XFER_TIMEOUT));
> -	if (!time_left)
> +	if (!time_left) {
> +		dev_err(i2c_dev->dev, "transfer timeout, I2C_STATUS = 0x%x\n",
> +			readl(i2c_dev->base + I2C_STATUS));
> +		if (i2c_dev->rst) {
> +			int ret = reset_control_reset(i2c_dev->rst);
> +
> +			if (ret < 0)
> +				dev_warn(i2c_dev->dev, "i2c soft reset failed, ret = %d\n", ret);
> +		}
>   		return -ETIMEDOUT;
> -
> +	}
>   	return i2c_dev->err;
>   }
>   
> @@ -544,6 +554,11 @@ static int sprd_i2c_probe(struct platform_device *pdev)
>   		return ret;
>   
>   	platform_set_drvdata(pdev, i2c_dev);
> +	i2c_dev->rst = devm_reset_control_get(i2c_dev->dev, "i2c_rst");

IMO, you need update the device binding file firstly.

> +	if (IS_ERR(i2c_dev->rst)) {
> +		dev_dbg(i2c_dev->dev, "reset control not configured!\n");
> +		i2c_dev->rst = NULL;
> +	}
>   
>   	ret = clk_prepare_enable(i2c_dev->clk);
>   	if (ret)