Re: [PATCH v5 07/18] iio: magnetometer: ak8975: modernize polling loops with iopoll() macros

[Andy Shevchenko]

On Tue, May 05, 2026 at 01:46:03PM +0200, Joshua Crofts via B4 Relay wrote:

> 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.

...

> +	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 val;
>  	}
> -	if (!timeout_ms)
> -		return -ETIMEDOUT;
>  
> -	return read_status;
> +	return val;

Besides the unneeded return val duplication, I think this is the wrong location
for this check and it changes behaviour (really subtle change!).

Before if the last iteration gives an error from the device, we return
-ETIMEDOUT instead of the whatever the i2c_smbus_read_byte_data() returns.


-- 
With Best Regards,
Andy Shevchenko