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

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Message-ID: <20251012191017.1ad05768@jic23-huawei>
Date: Sun, 12 Oct 2025 19:10:17 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Nuno Sá <noname.nuno@...il.com>
Cc: Antoniu Miclaus <antoniu.miclaus@...log.com>, 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, 07 Oct 2025 15:41:02 +0100
Nuno Sá <noname.nuno@...il.com> wrote:

> 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>

I'll tidy that up.

I'm currently taking a possibly controversial route with this patch.

Given I think we just get a false warning message without it, I'm going
to assume this isn't critical and queue it up for next merge window.
The advantage is I don't have to deal with tracking this patch going upstream
before I can apply the others in the series...

Shout if you'd prefer the harder route that gets this upstream faster.

Jonathan

> 
> > 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);
> >