From: George Liu <liuxiwei1013@gmail.com>
To: Paul Menzel <pmenzel@molgen.mpg.de>
Cc: openbmc@lists.ozlabs.org, joel@jms.id.au
Subject: Re: [PATCH] drivers: iio: pressure: dps310: Fix failure to read negative numbers
Date: Thu, 1 Feb 2024 16:52:14 +0800 [thread overview]
Message-ID: <CANFuQ7A08DZgmUavUQea_-ymQMeQ7hP9y9=e4BpBfM0u5PkEUQ@mail.gmail.com> (raw)
In-Reply-To: <bdb25a54-11c8-4925-9169-cb1a2ac18d93@molgen.mpg.de>
On Thu, Feb 1, 2024 at 4:32 PM Paul Menzel <pmenzel@molgen.mpg.de> wrote:
>
> Dear George,
>
>
> Thank you for your patch.
>
>
> Am 01.02.24 um 09:25 schrieb George Liu:
> > The dps310 chip driver fails to read the temperature when the
> > temperature reaches below zero.
>
> Stating, how you fixed this would also be nice.
>
> How did you test this?
Updated.
>
> > Signed-off-by: George Liu <liuxiwei@ieisystem.com>
> > ---
> > drivers/iio/pressure/dps310.c | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/iio/pressure/dps310.c b/drivers/iio/pressure/dps310.c
> > index 1ff091b2f764..fcbfdc5e85b7 100644
> > --- a/drivers/iio/pressure/dps310.c
> > +++ b/drivers/iio/pressure/dps310.c
> > @@ -730,7 +730,7 @@ static int dps310_read_pressure(struct dps310_data *data, int *val, int *val2,
> > }
> > }
> >
> > -static int dps310_calculate_temp(struct dps310_data *data)
> > +static int dps310_calculate_temp(struct dps310_data *data, int *val)
> > {
> > s64 c0;
> > s64 t;
> > @@ -746,7 +746,9 @@ static int dps310_calculate_temp(struct dps310_data *data)
> > t = c0 + ((s64)data->temp_raw * (s64)data->c1);
> >
> > /* Convert to milliCelsius and scale the temperature */
> > - return (int)div_s64(t * 1000LL, kt);
> > + *val = (int)div_s64(t * 1000LL, kt);
> > +
> > + return 0;
> > }
>
> This works, because `dps310_get_temp_k` returns the temperature in
> Kelvin which cannot be negative?
dps310_get_temp_k is correct, the problem is
`return (int)div_s64(t * 1000LL, kt);`
If it reaches below 0 degrees, a negative number will definitely be
returned here.
Then in the dps310_read_temp method, `val` will not be assigned a
value, but rc will be returned directly;
>
> static int dps310_get_temp_k(struct dps310_data *data)
> {
> int rc = dps310_get_temp_precision(data);
>
> if (rc < 0)
> return rc;
>
> return scale_factors[ilog2(rc)];
> }
>
>
> Kind regards,
>
> Paul
>
> > static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
> > @@ -768,11 +770,10 @@ static int dps310_read_temp(struct dps310_data *data, int *val, int *val2,
> > if (rc)
> > return rc;
> >
> > - rc = dps310_calculate_temp(data);
> > + rc = dps310_calculate_temp(data, val);
> > if (rc < 0)
> > return rc;
> >
> > - *val = rc;
> > return IIO_VAL_INT;
> >
> > case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
next prev parent reply other threads:[~2024-02-01 8:53 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-01 8:25 [PATCH] drivers: iio: pressure: dps310: Fix failure to read negative numbers George Liu
2024-02-01 8:32 ` Paul Menzel
2024-02-01 8:52 ` George Liu [this message]
-- strict thread matches above, loose matches on Subject: below --
2024-02-01 8:52 George Liu
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