Re: [PATCH v2] staging: iio: adc: ad7816: add mutex to serialize SPI/GPIO operations

[Dan Carpenter]

On Mon, Sep 01, 2025 at 10:24:45AM +0330, Mohammad Amin Hosseini wrote:
> @@ -200,7 +204,9 @@ static ssize_t ad7816_store_channel(struct device *dev,
>  		return -EINVAL;
>  	}
>  
> +	mutex_lock(&chip->io_lock);
>  	chip->channel_id = data;
> +	mutex_unlock(&chip->io_lock);
>  
>  	return len;
>  }

Unrelated, but what is the point of setting chip->channel_id to
AD7816_CS_MASK?  The only time where that is used is in
ad7816_spi_read() when we do:

	ret = spi_write(spi_dev, &chip->channel_id, sizeof(chip->channel_id));

So it's something in the hardware spec, I guess, but it isn't
documented.

regards,
dan carpenter