linux-kernel - Re: [PATCH v3 1/6] iio: adc: ad4080: fix chip identification

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Message-ID: <ba68afe4fbe5c895de8a2ce506a69e0c0884eb4e.camel@gmail.com>
Date: Tue, 07 Oct 2025 15:41:02 +0100
From: Nuno Sá <noname.nuno@...il.com>
To: Antoniu Miclaus <antoniu.miclaus@...log.com>, jic23@...nel.org, 
	robh@...nel.org, conor+dt@...nel.org, linux-iio@...r.kernel.org, 
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v3 1/6] iio: adc: ad4080: fix chip identification

On Tue, 2025-10-07 at 11:15 +0000, Antoniu Miclaus wrote:
> Fix AD4080 chip identification by using the correct 16-bit product ID
> (0x0050) instead of GENMASK(2, 0). Update the chip reading logic to
> use regmap_bulk_read to read both PRODUCT_ID_L and PRODUCT_ID_H
> registers and combine them into a 16-bit value.
> 
> The original implementation was incorrectly reading only 3 bits,
> which would not correctly identify the AD4080 chip.
> 
> Fixes: 6b31ba1811b6 ("iio: adc: ad4080: add driver support")
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@...log.com>
> ---

Small nitpick below that Jonathan might tweak if he thinks it's worth it.
Anyways,

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

> changes in v3:
>  - use le16_to_cpu to convert the read little-endian value to CPU endianness
>  drivers/iio/adc/ad4080.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad4080.c b/drivers/iio/adc/ad4080.c
> index 6e61787ed321..ae5a975a47a5 100644
> --- a/drivers/iio/adc/ad4080.c
> +++ b/drivers/iio/adc/ad4080.c
> @@ -125,7 +125,7 @@
>  
>  /* Miscellaneous Definitions */
>  #define
> AD4080_SPI_READ						BIT(7)
> -#define AD4080_CHIP_ID						GENMASK(2, 0)
> +#define AD4080_CHIP_ID						0x0050
>  
>  #define AD4080_LVDS_CNV_CLK_CNT_MAX				7
>  
> @@ -445,7 +445,8 @@ static int ad4080_setup(struct iio_dev *indio_dev)
>  {
>  	struct ad4080_state *st = iio_priv(indio_dev);
>  	struct device *dev = regmap_get_device(st->regmap);
> -	unsigned int id;
> +	__le16 id_le;
> +	u16 id;
>  	int ret;
>  
>  	ret = regmap_write(st->regmap, AD4080_REG_INTERFACE_CONFIG_A,
> @@ -458,10 +459,11 @@ static int ad4080_setup(struct iio_dev *indio_dev)
>  	if (ret)
>  		return ret;
>  
> -	ret = regmap_read(st->regmap, AD4080_REG_CHIP_TYPE, &id);
> +	ret = regmap_bulk_read(st->regmap, AD4080_REG_PRODUCT_ID_L, &id_le,
> 2);

sizeof(id_le)

>  	if (ret)
>  		return ret;
>  
> +	id = le16_to_cpu(id_le);
>  	if (id != AD4080_CHIP_ID)
>  		dev_info(dev, "Unrecognized CHIP_ID 0x%X\n", id);
>