linux-kernel - Re: [PATCH v3] thermal: rcar_thermal: Use platform_get_irq

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Message-ID: <CA+V-a8sGh0bCiDu_Eiz3EFgaDPmr-qyz95=dExwf+UvuyA21Cg@mail.gmail.com>
Date:   Wed, 5 Jan 2022 19:25:25 +0000
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Niklas Söderlund <niklas.soderlund@...natech.se>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Rob Herring <robh+dt@...nel.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] thermal: rcar_thermal: Use platform_get_irq_optional()
 to get the interrupt

Hi Niklas,

Thank you for the review.

On Wed, Jan 5, 2022 at 7:13 PM Niklas Söderlund
<niklas.soderlund@...natech.se> wrote:
>
> Hi Lad,
>
> Thanks for your work.
>
> On 2022-01-04 14:52:11 +0000, Lad Prabhakar wrote:
> > platform_get_resource(pdev, IORESOURCE_IRQ, ..) relies on static
> > allocation of IRQ resources in DT core code, this causes an issue
> > when using hierarchical interrupt domains using "interrupts" property
> > in the node as this bypasses the hierarchical setup and messes up the
> > irq chaining.
> >
> > In preparation for removal of static setup of IRQ resource from DT core
> > code use platform_get_irq_optional().
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > ---
> > v2-v3:
> > * Fixed review comment pointed by Andy
> >
> > v1->v2
> > * Simplified checking error code
> > * Break loop earlier if no interrupts are seen
> >
> > v1: https://lkml.org/lkml/2021/12/18/163
> > ---
> >  drivers/thermal/rcar_thermal.c | 17 ++++++++++++-----
> >  1 file changed, 12 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/thermal/rcar_thermal.c b/drivers/thermal/rcar_thermal.c
> > index b49f04daaf47..e480f7290ccf 100644
> > --- a/drivers/thermal/rcar_thermal.c
> > +++ b/drivers/thermal/rcar_thermal.c
> > @@ -445,7 +445,7 @@ static int rcar_thermal_probe(struct platform_device *pdev)
> >       struct rcar_thermal_common *common;
> >       struct rcar_thermal_priv *priv;
> >       struct device *dev = &pdev->dev;
> > -     struct resource *res, *irq;
> > +     struct resource *res;
> >       const struct rcar_thermal_chip *chip = of_device_get_match_data(dev);
> >       int mres = 0;
> >       int i;
> > @@ -467,9 +467,16 @@ static int rcar_thermal_probe(struct platform_device *pdev)
> >       pm_runtime_get_sync(dev);
> >
> >       for (i = 0; i < chip->nirqs; i++) {
> > -             irq = platform_get_resource(pdev, IORESOURCE_IRQ, i);
> > -             if (!irq)
> > -                     continue;
> > +             int irq;
> > +
> > +             irq = platform_get_irq_optional(pdev, i);
> > +             if (irq < 0 && irq != -ENXIO) {
> > +                     ret = irq;
> > +                     goto error_unregister;
> > +             }
> > +             if (!irq || irq == -ENXIO)
> > +                     break;
>
> This do not look correct and differs form v1.
>
> In the old code if we can't get an IRQ the loop is continued. This is
> used to detect if interrupts are supported or not on the platform.  This
> change will fail on all systems that don't describes interrupts in DT
> while the driver can function without interrupts.
>
There are no non-DT users for this driver. Do you see this driver
being used in a non-DT environment in near future?

> Is there a reason you wish to do this change in addition to the switch
> to platform_get_irq_optional()? If so I think that should be done in a
> separate patch.
>
No other reason, It was suggested by Gerrt too to use a break instead
of continue in v1.

Cheers,
Prabhakar