linux-kernel - Re: [PATCH] ata: pata_of_platform: Use of_irq_to

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Date:   Fri, 17 Dec 2021 01:16:22 +0000
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        linux-ide@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ata: pata_of_platform: Use of_irq_to_resource() to
 populate IRQ resource

Hi Damien,

Thank you for the review.

On Fri, Dec 17, 2021 at 12:23 AM Damien Le Moal
<damien.lemoal@...nsource.wdc.com> wrote:
>
> On 12/17/21 09:12, 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 bypassed the hierarchical setup and messed up the
>
> s/bypassed/bypasses
> s/messed/messes
>
Ok will update this.

> > irq chaining.
> >
> > In preparation for removal of static setup of IRQ resource from DT core
> > code use of_irq_to_resource().
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > ---
> > Hi,
> >
> > Dropping usage of platform_get_resource() was agreed based on
> > the discussion [0].
> >
> > [0] https://patchwork.kernel.org/project/linux-renesas-soc/
> > patch/20211209001056.29774-1-prabhakar.mahadev-lad.rj@...renesas.com/
> >
> > Cheers,
> > Prabhakar
> > ---
> >  drivers/ata/pata_of_platform.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/ata/pata_of_platform.c b/drivers/ata/pata_of_platform.c
> > index 35aa158fc976..557f349eb533 100644
> > --- a/drivers/ata/pata_of_platform.c
> > +++ b/drivers/ata/pata_of_platform.c
> > @@ -9,6 +9,7 @@
> >  #include <linux/kernel.h>
> >  #include <linux/module.h>
> >  #include <linux/of_address.h>
> > +#include <linux/of_irq.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/ata_platform.h>
> >  #include <linux/libata.h>
> > @@ -25,11 +26,12 @@ static int pata_of_platform_probe(struct platform_device *ofdev)
> >       struct device_node *dn = ofdev->dev.of_node;
> >       struct resource io_res;
> >       struct resource ctl_res;
> > -     struct resource *irq_res;
> > +     struct resource irq_res;
> >       unsigned int reg_shift = 0;
> >       int pio_mode = 0;
> >       int pio_mask;
> >       bool use16bit;
> > +     int irq;
> >
> >       ret = of_address_to_resource(dn, 0, &io_res);
> >       if (ret) {
> > @@ -45,7 +47,9 @@ static int pata_of_platform_probe(struct platform_device *ofdev)
> >               return -EINVAL;
> >       }
> >
> > -     irq_res = platform_get_resource(ofdev, IORESOURCE_IRQ, 0);
> > +     irq = of_irq_to_resource(dn, 0, &irq_res);
> > +     if (irq <= 0 && irq != -ENXIO)
> > +             return irq ? irq : -ENXIO;
>
> Why are you making an exception for ENXIO ? I suspect this is to cover
> the case "there is no IRQ for this node", but then how does this
> differentiate from a real error case ?
>
-ENXIO to handle no interrupt case. In case of actual error case we
fallback to polling mode..

> >
> >       of_property_read_u32(dn, "reg-shift", &reg_shift);
> >
> > @@ -63,7 +67,8 @@ static int pata_of_platform_probe(struct platform_device *ofdev)
> >       pio_mask = 1 << pio_mode;
> >       pio_mask |= (1 << pio_mode) - 1;
> >
> > -     return __pata_platform_probe(&ofdev->dev, &io_res, &ctl_res, irq_res,
> > +     return __pata_platform_probe(&ofdev->dev, &io_res, &ctl_res,
> > +                                  irq > 0 ? &irq_res : NULL,
.. here is check for irq number again.

Cheers,
Prabhakar
> >                                    reg_shift, pio_mask, &pata_platform_sht,
> >                                    use16bit);
> >  }
> >
>
>
> --
> Damien Le Moal
> Western Digital Research