linux-kernel - Re: [PATCH v1 2/2] iio: adc: ti-adc128s052: replace literal by unit expression

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Message-ID: <20250626192014.4dd4a270@jic23-huawei>
Date: Thu, 26 Jun 2025 19:20:14 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Matti Vaittinen <mazziesaccount@...il.com>
Cc: Lothar Rubusch <l.rubusch@...il.com>, dlechner@...libre.com,
 nuno.sa@...log.com, andy@...nel.org, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/2] iio: adc: ti-adc128s052: replace literal by unit
 expression

On Thu, 26 Jun 2025 08:07:19 +0300
Matti Vaittinen <mazziesaccount@...il.com> wrote:

> On 25/06/2025 20:02, Lothar Rubusch wrote:
> > Replace the literal number 1000 by MILLI from linux/units.h
> > 
> > Signed-off-by: Lothar Rubusch <l.rubusch@...il.com>
> > ---
> >   drivers/iio/adc/ti-adc128s052.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iio/adc/ti-adc128s052.c b/drivers/iio/adc/ti-adc128s052.c
> > index cf271c39e663..67bc7fbd52bc 100644
> > --- a/drivers/iio/adc/ti-adc128s052.c
> > +++ b/drivers/iio/adc/ti-adc128s052.c
> > @@ -18,6 +18,7 @@
> >   #include <linux/property.h>
> >   #include <linux/regulator/consumer.h>
> >   #include <linux/spi/spi.h>
> > +#include <linux/units.h>
> >   
> >   struct adc128_configuration {
> >   	const struct iio_chan_spec	*channels;
> > @@ -189,7 +190,7 @@ static int adc128_probe(struct spi_device *spi)
> >   				     "failed to read '%s' voltage",
> >   				     config->refname);
> >   
> > -	adc->vref_mv = ret / 1000;
> > +	adc->vref_mv = ret / MILLI;  
> 
> This makes no sense to me. What does it mean we divide the micro volts 
> by 'milli'? It is clear when we divide micro volts by 1000 that we get 
> milli volts. Also, the mv suffix in variable makes units clear already, 
> division by MILLI just obfuscates things. I'd keep it as 1000.
> 

ret / (MICRO / MILLI) would be more descriptive as indicates
we are converting form microvolts to milivolts.
 
> I would just drop this unless Jonathan disagrees.
> 
> Yours,
> 	-- Matti