Re: [PATCH] iio: adc: ad4080: enable address ascension for chip identification

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 22 Sep 2026 15:15:19 +0100
Nuno Sá <nuno.sa@analog.com> wrote:

> On Tue, Sep 22, 2026 at 02:09:58PM +0300, Antoniu Miclaus wrote:
> > The two byte bulk read at AD4080_REG_PRODUCT_ID_L expects PRODUCT_ID_L
> > followed by PRODUCT_ID_H. After a software reset the AD408x defaults to
> > descending address mode, so the second byte comes from CHIP_TYPE (0x03)
> > instead. CHIP_TYPE reads 0x07 on all AD408x parts, so an AD4080 reports
> > 0x0750 rather than 0x0050 and every part logs "Unrecognized CHIP_ID".
> > 
> > Set ADDR_ASC along with SDO_ENABLE before the read. This is the only
> > multi byte transfer in the driver, so no other access is affected.
> > 
> > Fixes: b66cddc8be72 ("iio: adc: ad4080: fix chip identification")
> > Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> > ---  
> 
> You could also just use change AD4080_REG_PRODUCT_ID_L to
> AD4080_REG_PRODUCT_ID_H (maybe a slight smaller diff). Nut no strong
> feelings:
> 
> Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Applied to the testing branch of iio.git and marked for stable.
I think this one can wait for the merge window. In reality it
is likely so will all the other fixes I currently have on the iio-fixes
branch.

Thanks.

Jonathan

> 
> >  drivers/iio/adc/ad4080.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iio/adc/ad4080.c b/drivers/iio/adc/ad4080.c
> > index 4843ecdd91a8..4ed82aa42400 100644
> > --- a/drivers/iio/adc/ad4080.c
> > +++ b/drivers/iio/adc/ad4080.c
> > @@ -710,7 +710,8 @@ static int ad4080_setup_channel(struct ad4080_state *st, unsigned int ch)
> >  		return ret;
> >  
> >  	ret = regmap_write(st->regmap[ch], AD4080_REG_INTERFACE_CONFIG_A,
> > -			   AD4080_INTERFACE_CONFIG_A_SDO_ENABLE);
> > +			   AD4080_INTERFACE_CONFIG_A_SDO_ENABLE |
> > +			   AD4080_INTERFACE_CONFIG_A_ADDR_ASC);
> >  	if (ret)
> >  		return ret;
> >  
> > 
> > base-commit: dceba8e581e3e8f475da0efbd7a73f3d9524ddd2
> > -- 
> > 2.43.0
> >