linux-kernel - Re: [PATCH v4 4/9] staging:iio:ad7780: add chip ID values and mask

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Message-ID: <13ef212f8aeebd0c893be253cb4834a3e4d741b8.camel@analog.com>
Date:   Mon, 4 Mar 2019 07:33:51 +0000
From:   "Ardelean, Alexandru" <Alex.Ardelean@...log.com>
To:     "renatogeh@...il.com" <renatogeh@...il.com>,
        "jic23@...nel.org" <jic23@...nel.org>
CC:     "kernel-usp@...glegroups.com" <kernel-usp@...glegroups.com>,
        "lars@...afoo.de" <lars@...afoo.de>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "knaack.h@....de" <knaack.h@....de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "Hennerich, Michael" <Michael.Hennerich@...log.com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "giuliano.belinassi@....br" <giuliano.belinassi@....br>,
        "Ardelean, Alexandru" <Alex.Ardelean@...log.com>,
        "pmeerw@...erw.net" <pmeerw@...erw.net>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "Popa, Stefan Serban" <StefanSerban.Popa@...log.com>
Subject: Re: [PATCH v4 4/9] staging:iio:ad7780: add chip ID values and mask

On Sun, 2019-03-03 at 14:53 +0000, Jonathan Cameron wrote:
> [External]
> 
> 
> On Sun, 3 Mar 2019 11:01:09 -0300
> Renato Lui Geh <renatogeh@...il.com> wrote:
> 
> > On 03/01, Ardelean, Alexandru wrote:
> > > On Thu, 2019-02-28 at 11:24 -0300, Renato Lui Geh wrote:
> > > > 
> > > > 
> > > > The ad7780 supports both the ad778x and ad717x families. Each chip
> > > > has
> > > > a corresponding ID. This patch provides a mask for extracting ID
> > > > values
> > > > from the status bits and also macros for the correct values for the
> > > > ad7170, ad7171, ad7780 and ad7781.
> > > > 
> > > > Signed-off-by: Renato Lui Geh <renatogeh@...il.com>
> > > > ---
> > > >  drivers/staging/iio/adc/ad7780.c | 8 ++++++--
> > > >  1 file changed, 6 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/drivers/staging/iio/adc/ad7780.c
> > > > b/drivers/staging/iio/adc/ad7780.c
> > > > index 56c49e28f432..ad7617a3a141 100644
> > > > --- a/drivers/staging/iio/adc/ad7780.c
> > > > +++ b/drivers/staging/iio/adc/ad7780.c
> > > > @@ -26,10 +26,14 @@
> > > >  #define AD7780_RDY             BIT(7)
> > > >  #define AD7780_FILTER          BIT(6)
> > > >  #define AD7780_ERR             BIT(5)
> > > > -#define AD7780_ID1             BIT(4)
> > > > -#define AD7780_ID0             BIT(3)
> > > >  #define AD7780_GAIN            BIT(2)
> > > > 
> > > > +#define AD7170_ID              0
> > > > +#define AD7171_ID              1
> > > > +#define AD7780_ID              1
> > > > +#define AD7781_ID              0
> > > > +
> > > > +#define AD7780_ID_MASK         (BIT(3) | BIT(4))
> > > 
> > > This also doesn't have any functionality change.
> > > The AD7170_ID, AD7171_ID, AD7780_ID & AD7781_ID IDs are also unused
> > > (maybe
> > > in a later patch they are ?).
> > 
> > They aren't. I added them following a previous review suggestion.
> > Should
> > I remove them?
> 
> Can we check them?  It's always useful to confirm that the device is
> the one you think it is.  Then we can either use what is there
> with a suitable warning, or if that is tricky just fault out as the
> dt is giving us the wrong part number.
> 
> J

I guess `dev_warn_ratelimited()` could be used to make sure syslog isn't
spammed-to-death when doing multiple conversions, and the ID isn't correct.
Since these IDs are read after you get a sample, I'm a bit fearful of log-
spam.

I wouldn't throw an error in the ad7780_postprocess_sample() for this, but
warning [with rate-limit] sounds reasonable.

> 
> > > 
> > > I would also leave the AD7780_ID1 & AD7780_ID0 definitions in place,
> > > since
> > > they're easier matched with the datasheet.
> > > 
> > > > 
> > > >  #define AD7780_PATTERN_GOOD    1
> > > >  #define AD7780_PATTERN_MASK    GENMASK(1, 0)
> > > > --
> > > > 2.21.0
> > > > 
> 
>