linux-kernel - Re: [PATCH v6 02/14] of: property: Add fw

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Message-ID: <CAK9=C2W+3pOWL36ZPme1LpHz5PEBVdKWv+kR7DYKmRyw1AymMA@mail.gmail.com>
Date:   Thu, 20 Jul 2023 10:51:22 +0530
From:   Anup Patel <apatel@...tanamicro.com>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Frank Rowand <frowand.list@...il.com>,
        Conor Dooley <conor+dt@...nel.org>,
        Atish Patra <atishp@...shpatra.org>,
        Andrew Jones <ajones@...tanamicro.com>,
        Sunil V L <sunilvl@...tanamicro.com>,
        Anup Patel <anup@...infault.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v6 02/14] of: property: Add fw_devlink support for msi-parent

On Thu, Jul 20, 2023 at 3:55 AM Saravana Kannan <saravanak@...gle.com> wrote:
>
> On Wed, Jul 19, 2023 at 4:36 AM Anup Patel <apatel@...tanamicro.com> wrote:
> >
> > This allows fw_devlink to create device links between consumers of
> > a MSI and the supplier of the MSI.
> >
> > Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> > ---
> >  drivers/of/property.c | 32 ++++++++++++++++++++++++++++++++
> >  1 file changed, 32 insertions(+)
> >
> > diff --git a/drivers/of/property.c b/drivers/of/property.c
> > index ddc75cd50825..e4096b79a872 100644
> > --- a/drivers/of/property.c
> > +++ b/drivers/of/property.c
> > @@ -1325,6 +1325,37 @@ static struct device_node *parse_interrupts(struct device_node *np,
> >         return of_irq_parse_one(np, index, &sup_args) ? NULL : sup_args.np;
> >  }
> >
> > +static struct device_node *parse_msi_parent(struct device_node *np,
> > +                                           const char *prop_name, int index)
> > +{
> > +       struct of_phandle_args sup_args;
> > +       struct device_node *msi_np;
> > +
> > +       if (!IS_ENABLED(CONFIG_OF_IRQ))
> > +               return NULL;
> > +
> > +       if (strcmp(prop_name, "msi-parent"))
> > +               return NULL;
> > +
> > +       msi_np = of_parse_phandle(np, prop_name, 0);
> > +       if (msi_np) {
> > +               if (!of_property_read_bool(msi_np, "#msi-cells")) {
> > +                       if (index) {
> > +                               of_node_put(msi_np);
> > +                               return NULL;
> > +                       }
> > +                       return msi_np;
> > +               }
> > +               of_node_put(msi_np);
> > +       }
> > +
> > +       if (of_parse_phandle_with_args(np, prop_name, "#msi-cells", index,
> > +                                      &sup_args))
> > +               return NULL;
> > +
> > +       return sup_args.np;
> > +}
> > +
>
> I'm amazed by the different ways you choose to waste people's time.
> Did you even scroll up to see how the other properties are handled?
>
> Why can't this be handled using DEFINE_SIMPLE_PROP macro?

DEFINE_SIMPLE_PROP() is not suitable for msi-parent because we
have a special case where for a single MSI parent the "#msi-cells"
property won't be present in the supplier DT node.

The of_msi_get_domain() function also handles this special case
separately.

Regards,
Anup


>
> -Saravana
>
> >  static const struct supplier_bindings of_supplier_bindings[] = {
> >         { .parse_prop = parse_clocks, },
> >         { .parse_prop = parse_interconnects, },
> > @@ -1359,6 +1390,7 @@ static const struct supplier_bindings of_supplier_bindings[] = {
> >         { .parse_prop = parse_regulators, },
> >         { .parse_prop = parse_gpio, },
> >         { .parse_prop = parse_gpios, },
> > +       { .parse_prop = parse_msi_parent, },
> >         {}
> >  };
> >
> > --
> > 2.34.1
> >