linux-kernel - Re: [PATCH 1/3] i2c: bcm2835: Use platform_get

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Date:   Sun, 19 Dec 2021 09:52:42 +0000
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Rob Herring <robh+dt@...nel.org>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Chris Brandt <chris.brandt@...esas.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Linux I2C <linux-i2c@...r.kernel.org>,
        linux-rpi-kernel@...ts.infradead.org,
        LAK <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH 1/3] i2c: bcm2835: Use platform_get_irq() to get the interrupt

Hi Florian,

On Sat, Dec 18, 2021 at 10:44 PM Lad, Prabhakar
<prabhakar.csengg@...il.com> wrote:
>
> Hi Florian,
>
> Thank you for the review.
>
> On Sat, Dec 18, 2021 at 9:17 PM Florian Fainelli <f.fainelli@...il.com> wrote:
> >
> >
> >
> > On 12/18/2021 8:52 AM, 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().
> > >
> > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > Just one nit below:
> > > ---
> > >   drivers/i2c/busses/i2c-bcm2835.c | 11 ++++-------
> > >   1 file changed, 4 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c
> > > index 37443edbf754..d63dec5f3cb1 100644
> > > --- a/drivers/i2c/busses/i2c-bcm2835.c
> > > +++ b/drivers/i2c/busses/i2c-bcm2835.c
> > > @@ -402,7 +402,7 @@ static const struct i2c_adapter_quirks bcm2835_i2c_quirks = {
> > >   static int bcm2835_i2c_probe(struct platform_device *pdev)
> > >   {
> > >       struct bcm2835_i2c_dev *i2c_dev;
> > > -     struct resource *mem, *irq;
> > > +     struct resource *mem;
> > >       int ret;
> > >       struct i2c_adapter *adap;
> > >       struct clk *mclk;
> > > @@ -452,12 +452,9 @@ static int bcm2835_i2c_probe(struct platform_device *pdev)
> > >               return ret;
> > >       }
> > >
> > > -     irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> > > -     if (!irq) {
> > > -             dev_err(&pdev->dev, "No IRQ resource\n");
> > > -             return -ENODEV;
> > > -     }
> > > -     i2c_dev->irq = irq->start;
> > > +     i2c_dev->irq = platform_get_irq(pdev, 0);
> > > +     if (i2c_dev->irq <= 0)
> > > +             return i2c_dev->irq ? i2c_dev->irq : -ENXIO;
> >
> > Why not just check for a negative return code and propagate it as is?
> >
> platform_get_irq() may return 0 said that we do get a splat in this
> case and further request_irq() will fail so instead check it here.
>
My bad, just the negative check should suffice.

Cheers,
Prabhakar