Re: [PATCH v5 1/2] staging: iio: adc: ad7816: Serialize SPI read operations

[Joshua Crofts]

On Fri, 11 Sep 2026 14:04:55 +0300
Abdelnasser Hussein <abdelnasserhussein11@xxxxxxxxx> wrote:

...

> -#include <linux/interrupt.h>
> -#include <linux/gpio/consumer.h>
> +#include <linux/cleanup.h>
>  #include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/interrupt.h>
>  #include <linux/kernel.h>
> -#include <linux/slab.h>
> -#include <linux/sysfs.h>
>  #include <linux/list.h>
> -#include <linux/spi/spi.h>
>  #include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include <linux/spi/spi.h>
> +#include <linux/sysfs.h>
>  

Ideally the addition of new headers should go in a separate precursor patch.
(excluding cleanup.h and mutex.h, you'd add those in this patch).

>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
> @@ -50,6 +52,7 @@ struct ad7816_chip_info {
>  	u8  oti_data[AD7816_CS_MAX + 1];
>  	u8  channel_id;	/* 0 always be temperature */
>  	u8  mode;
> +	struct mutex lock; /* protect device state during SPI transfers */
>  };
>  
>  enum ad7816_type {
> @@ -67,6 +70,8 @@ static int ad7816_spi_read(struct ad7816_chip_info *chip, u16 *data)
>  	int ret;
>  	__be16 buf;
>  
> +	guard(mutex)(&chip->lock);
> +
>  	gpiod_set_value(chip->rdwr_pin, 1);
>  	gpiod_set_value(chip->rdwr_pin, 0);
>  	ret = spi_write(spi_dev, &chip->channel_id, sizeof(chip->channel_id));
> @@ -91,7 +96,7 @@ static int ad7816_spi_read(struct ad7816_chip_info *chip, u16 *data)
>  
>  	gpiod_set_value(chip->rdwr_pin, 0);
>  	gpiod_set_value(chip->rdwr_pin, 1);
> -	ret = spi_read(spi_dev, &buf, sizeof(*data));
> +	ret = spi_read(spi_dev, &buf, sizeof(buf));

No, you're mixing changes again.

-- 
Kind regards,
Joshua Crofts