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SubjectRe: [PATCH 04/12] iio: adc: max9611: Fix misuse of GENMASK macro
On Mon, 29 Jul 2019 23:52:14 +0200
Jacopo Mondi <jacopo@jmondi.org> wrote:

> Hello,
> so I finally run some test and...
>
> On Sun, Jul 14, 2019 at 05:19:32AM -0700, Joe Perches wrote:
> > On Sun, 2019-07-14 at 12:54 +0100, Jonathan Cameron wrote:
> > > On Tue, 9 Jul 2019 22:04:17 -0700
> > > Joe Perches <joe@perches.com> wrote:
> > >
> > > > Arguments are supposed to be ordered high then low.
> > > >
> > > > Signed-off-by: Joe Perches <joe@perches.com>
> > >
> > > Applied to the fixes-togreg branch of iio.git and marked for
> > > stable etc.
>
> I don't see it in v5.3-rc2, has it been collected or are we still in
> time for an additional fix?
>
> >
> > This mask is used in an init function called from a probe.
> >
> > I don't have this hardware but it looks as if it could
> > never have worked so I doubt the driver and the hardware
> > have ever been tested.
> >
> > Does anyone have this device in actual use?
>
> Because it turns out this is 2 times embarrassing. The mask definition
> is indeed wrong, as Joe reported and fixed, but also this line
> >
> > regval = ret & MAX9611_TEMP_MASK;
>
> is very wrong as regval is read as:
> ret = max9611_read_single(max9611, CONF_TEMP, &regval);
>
> So that should actually be:
> regval &= MAX9611_TEMP_MASK;
> not
> regval = ret & MAX9611_TEMP_MASK;
> Ups...
>
> Yes, it worked by chance, as regval was always 0, which is in the
> range of acceptable temperatures :/
>
> >
> > if ((regval > MAX9611_TEMP_MAX_POS &&
> > regval < MAX9611_TEMP_MIN_NEG) ||
> > regval > MAX9611_TEMP_MAX_NEG) {
>
> Also reading this condition and how I had defined the temperature
> calculation formula makes me wonder if this it totally correct, but
> for the moment:
>
> 1) if Joe's patch has been collected, I can send an additional patch to
> fix how regval is computed.
> 2) If Joe's patch still have to be collected, the regval computation
> might be fixed there.

I think this will have hit linux-next on the same day as your email.

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/iio/adc?id=ae8cc91a7d85e018c0c267f580820b2bb558cd48

So follow up patch please.

Thanks!

Jonathan
>
> Sorry for taking so long to get back to you and thanks for noticing.
>
> Thanks
> j
>
> > dev_err(max9611->dev,
> > "Invalid value received from ADC 0x%4x: aborting\n",
> > regval);
> > return -EIO;
> > }
> >
> >
> > > Thanks,
> > >
> > > Jonathan
> > >
> > > > ---
> > > > drivers/iio/adc/max9611.c | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/iio/adc/max9611.c b/drivers/iio/adc/max9611.c
> > > > index 917223d5ff5b..0e3c6529fc4c 100644
> > > > --- a/drivers/iio/adc/max9611.c
> > > > +++ b/drivers/iio/adc/max9611.c
> > > > @@ -83,7 +83,7 @@
> > > > #define MAX9611_TEMP_MAX_POS 0x7f80
> > > > #define MAX9611_TEMP_MAX_NEG 0xff80
> > > > #define MAX9611_TEMP_MIN_NEG 0xd980
> > > > -#define MAX9611_TEMP_MASK GENMASK(7, 15)
> > > > +#define MAX9611_TEMP_MASK GENMASK(15, 7)
> > > > #define MAX9611_TEMP_SHIFT 0x07
> > > > #define MAX9611_TEMP_RAW(_r) ((_r) >> MAX9611_TEMP_SHIFT)
> > > > #define MAX9611_TEMP_SCALE_NUM 1000000
> >
>


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