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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Mon, 4 Jul 2022 23:51:32 +0200
Message-ID: <CAHp75VeiuJjiPFFh0pEGGH4+UEn0g5902UhAJL93Ho2WvH0_gg@mail.gmail.com>
Subject: Re: [PATCH v2 2/2] iio: adc: Add rtq6056 support
To:     ChiYuan Huang <u0084500@gmail.com>
Cc:     Jonathan Cameron <jic23@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        cy_huang <cy_huang@richtek.com>,
        linux-iio <linux-iio@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>
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On Mon, Jul 4, 2022 at 9:27 AM ChiYuan Huang <u0084500@gmail.com> wrote:
> ChiYuan Huang <u0084500@gmail.com> =E6=96=BC 2022=E5=B9=B47=E6=9C=884=E6=
=97=A5 =E9=80=B1=E4=B8=80 =E4=B8=8A=E5=8D=8811:16=E5=AF=AB=E9=81=93=EF=BC=
=9A
> > Andy Shevchenko <andy.shevchenko@gmail.com> =E6=96=BC 2022=E5=B9=B47=E6=
=9C=881=E6=97=A5 =E9=80=B1=E4=BA=94 =E4=B8=8B=E5=8D=886:05=E5=AF=AB=E9=81=
=93=EF=BC=9A
> > > On Wed, Jun 29, 2022 at 4:23 AM cy_huang <u0084500@gmail.com> wrote:

...

> > > > +       *val =3D DIV_ROUND_UP(1000000, sample_time);
> > >
> > > USEC_PER_SEC ?
> > >
> > No, sample time is (vshunt convesion time + vbus conversion time) *
> > average sample.
> > And the sample freq returns the unit by HZ (sample frequency per second=
)
> >
> The 'sample time' is unit by micro-second like as you mentioned.

Ah, then it should be MICRO, so we will get Hz.

> > > > +       return IIO_VAL_INT;
> > > > +}

...

> > > > +       struct {
> > > > +               u16 vals[RTQ6056_MAX_CHANNEL];
> > > > +               int64_t timestamp;
> > > > +       } data __aligned(8);
> > >
> > > Hmm... alignment of this struct will be at least 4 bytes, but
> > > shouldn't we rather be sure that the timestamp member is aligned
> > > properly? Otherwise this seems fragile and dependent on
> > > RTQ6056_MAX_CHANNEL % 4 =3D=3D 0.
> > >
> > Yap, from the 'max channel', it already guarantee this struct will be
> > aligned at lease 4.
> > Actually, It can be removed.

I think for the safest side it should be given to the timestamp member. No?

--=20
With Best Regards,
Andy Shevchenko