Re: [PATCH 1/8] iio: magnetometer: ak8975: modernize polling loops with iopoll() macros

[Nuno Sá]

On Thu, 2026-05-07 at 16:35 +0200, Joshua Crofts via B4 Relay wrote:
> From: Joshua Crofts <joshua.crofts1@xxxxxxxxx>
> 
> The driver currently uses while loops and msleep() for polling during
> conversion waits.
> 
> Replace the custom polling loops with readx_poll_timeout() and
> read_poll_timeout() macros from <linux/iopoll.h>. This reduces
> boilerplate, standardizes timeout handling and improves overall code
> readability, keeping the original timing and error behaviour. Add
> <linux/time.h> for USEC_PER_MSEC macro instead of using magic numbers.
> 
> Assisted-by: Gemini:3.1-Pro
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Signed-off-by: Joshua Crofts <joshua.crofts1@xxxxxxxxx>
> ---

Reviewed-by: Nuno Sá <nuno.sa@xxxxxxxxxx>

>  drivers/iio/magnetometer/ak8975.c | 43 ++++++++++++++++-----------------------
>  1 file changed, 18 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
> index
> 6be72e1cc0a8321e767da5e65d54c0fe88712304..b990c123e2808c2078abcfaf6b2ef86c09393e6b
> 100644
> --- a/drivers/iio/magnetometer/ak8975.c
> +++ b/drivers/iio/magnetometer/ak8975.c
> @@ -24,6 +24,7 @@
>  #include <linux/pm_runtime.h>
>  #include <linux/property.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/time.h>
>  #include <linux/types.h>
>  #include <linux/wait.h>
>  
> @@ -649,16 +650,14 @@ static int wait_conversion_complete_gpio(struct ak8975_data
> *data,
>  {
>  	struct i2c_client *client = data->client;
>  	int ret;
> +	int val;
>  
>  	/* Wait for the conversion to complete. */
> -	while (timeout_ms) {
> -		msleep(poll_ms);
> -		if (gpiod_get_value(data->eoc_gpiod))
> -			break;
> -		timeout_ms -= poll_ms;
> -	}
> -	if (!timeout_ms)
> -		return -ETIMEDOUT;
> +	ret = readx_poll_timeout(gpiod_get_value, data->eoc_gpiod, val, val != 0,
> +				 poll_ms * USEC_PER_MSEC,
> +				 timeout_ms * USEC_PER_MSEC);
> +	if (ret)
> +		return ret;
>  
>  	ret = i2c_smbus_read_byte_data(client, data->def->ctrl_regs[ST1]);
>  	if (ret < 0)
> @@ -672,27 +671,21 @@ static int wait_conversion_complete_polled(struct ak8975_data
> *data,
>  					   unsigned int timeout_ms)
>  {
>  	struct i2c_client *client = data->client;
> -	u8 read_status;
>  	int ret;
> +	int val;
>  
>  	/* Wait for the conversion to complete. */
> -	while (timeout_ms) {
> -		msleep(poll_ms);
> -		ret = i2c_smbus_read_byte_data(client,
> -					       data->def->ctrl_regs[ST1]);
> -		if (ret < 0) {
> -			dev_err(&client->dev, "Error in reading ST1\n");
> -			return ret;
> -		}
> -		read_status = ret;
> -		if (read_status)
> -			break;
> -		timeout_ms -= poll_ms;
> -	}
> -	if (!timeout_ms)
> -		return -ETIMEDOUT;
> +	ret = read_poll_timeout(i2c_smbus_read_byte_data, val, val != 0,
> +				poll_ms * USEC_PER_MSEC,
> +				timeout_ms * USEC_PER_MSEC,
> +				true,
> +				client, data->def->ctrl_regs[ST1]);
> +	if (ret)
> +		return ret;
> +	if (val < 0)
> +		dev_err(&client->dev, "Error in reading ST1\n");
>  
> -	return read_status;
> +	return val;
>  }
>  
>  /* Returns 0 if the end of conversion interrupt occurred or -ETIMEDOUT otherwise
> */