netdev - Re: [PATCH v2 1/2] can: tcan4x5x: add option for selecting nWKRQ voltage

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Message-ID: <CAMZ6RqJ0SMojXS5sbZBxeA9t6Q_=ns_dV5DCyyZJu2DjNzMsFg@mail.gmail.com>
Date: Thu, 14 Nov 2024 17:36:16 +0900
From: Vincent Mailhol <mailhol.vincent@...adoo.fr>
To: Sean Nyekjaer <sean@...nix.com>
Cc: Marc Kleine-Budde <mkl@...gutronix.de>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-can@...r.kernel.org, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 1/2] can: tcan4x5x: add option for selecting nWKRQ voltage

On Thu. 14 Nov. 2024 at 16:33, Sean Nyekjaer <sean@...nix.com> wrote:
> Hi Vincent,
> On Thu, Nov 14, 2024 at 01:53:34PM +0100, Vincent Mailhol wrote:
> > On Mon. 11 Nov. 2024 at 17:55, Sean Nyekjaer <sean@...nix.com> wrote:
> > > nWKRQ supports an output voltage of either the internal reference voltage
> > > (3.6V) or the reference voltage of the digital interface 0 - 6V.
> > > Add the devicetree option ti,nwkrq-voltage-sel to be able to select
> > > between them.
> > > Default is kept as the internal reference voltage.
> > >
> > > Signed-off-by: Sean Nyekjaer <sean@...nix.com>
> > > ---
> > >  drivers/net/can/m_can/tcan4x5x-core.c | 35 +++++++++++++++++++++++++++++++++++
> > >  drivers/net/can/m_can/tcan4x5x.h      |  2 ++
> > >  2 files changed, 37 insertions(+)
> > >
>
> [...]
>
> > >
> > > +static int tcan4x5x_get_dt_data(struct m_can_classdev *cdev)
> > > +{
> > > +       struct tcan4x5x_priv *tcan4x5x = cdev_to_priv(cdev);
> > > +       struct device_node *np = cdev->dev->of_node;
> > > +       u8 prop;
> > > +       int ret;
> > > +
> > > +       ret = of_property_read_u8(np, "ti,nwkrq-voltage-sel", &prop);
> > > +       if (!ret) {
> > > +               if (prop <= 1)
> > > +                       tcan4x5x->nwkrq_voltage = prop;
> > > +               else
> > > +                       dev_warn(cdev->dev,
> > > +                                "nwkrq-voltage-sel have invalid option: %u\n",
> > > +                                prop);
> > > +       } else {
> > > +               tcan4x5x->nwkrq_voltage = 0;
> > > +       }
> >
> > If the
> >
> >   if (prop <= 1)
> >
> > condition fails, you print a warning, but you are not assigning a
> > value to tcan4x5x->nwkrq_voltage. Is this intentional?
> >
> > What about:
> >
> >         tcan4x5x->nwkrq_voltage = 0;
> >         ret = of_property_read_u8(np, "ti,nwkrq-voltage-sel", &prop);
> >         if (!ret) {
> >                 if (prop <= 1)
> >                         tcan4x5x->nwkrq_voltage = prop;
> >                 else
> >                         dev_warn(cdev->dev,
> >                                  "nwkrq-voltage-sel have invalid option: %u\n",
> >                                  prop);
> >         }
> >
> > so that you make sure that tcan4x5x->nwkrq_voltage always gets a
> > default zero value? Else, if you can make sure that tcan4x5x is always
> > zero initialized, you can just drop the
> >
> >         tcan4x5x->nwkrq_voltage = 0;
> >
> > thing.
>
> Thanks for the review.
> You are right, so I reworked this for v3:
> https://lore.kernel.org/r/20241112-tcan-wkrqv-v3-0-c66423fba26d@geanix.com

I see. So this v2 was already outdated at the time of my review. Well,
glad to hear that this was proactively fixed in the v3 and sorry for
missing that.

Yours sincerely,
Vincent Mailhol