Subject: Re: [PATCH] thermal: rcar_thermal: Use platform_get_irq_optional() to
 get the interrupt
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>,
        =?UTF-8?Q?Niklas_S=c3=b6derlund?= <niklas.soderlund@ragnatech.se>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Amit Kucheria <amitk@kernel.org>,
        Zhang Rui <rui.zhang@intel.com>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        Linux PM list <linux-pm@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Prabhakar <prabhakar.csengg@gmail.com>
References: <20211218144136.6663-1-prabhakar.mahadev-lad.rj@bp.renesas.com>
 <5f8e2432-1214-3435-fb62-2f407ced0472@linaro.org>
 <CAMuHMdXgRzM4+OjR0or0aTk-ogPcAYajaVALsLF6E=MxEzeRQg@mail.gmail.com>
From:   Daniel Lezcano <daniel.lezcano@linaro.org>
Message-ID: <bdec1a89-ad1b-1e16-a248-029f7f02ae80@linaro.org>
Date:   Mon, 20 Dec 2021 15:19:13 +0100
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On 20/12/2021 14:48, Geert Uytterhoeven wrote:
> On Mon, Dec 20, 2021 at 1:29 PM Daniel Lezcano
> <daniel.lezcano@linaro.org> wrote:
>> On 18/12/2021 15:41, 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@bp.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@bp.renesas.com/
>>>
>>> Cheers,
>>> Prabhakar
>>> ---
>>>  drivers/thermal/rcar_thermal.c | 15 +++++++++++----
>>>  1 file changed, 11 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/thermal/rcar_thermal.c b/drivers/thermal/rcar_thermal.c
>>> index b49f04daaf47..e4c7bc1bf7ef 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)
>>> +             int irq;
>>> +
>>> +             irq = platform_get_irq_optional(pdev, i);
>>> +             if (irq <= 0 && irq != -ENXIO) {
>>> +                     ret = irq ? irq : -ENXIO;
>>> +                     goto error_unregister;
>>> +             }
>>> +             if (irq == -ENXIO)
>>>                       continue;
>>
>> Why not invert the conditions?
>>
>>                 if (irq == -ENXIO)
>>                         continue;
> 
> And this can be break.
> 
>>
>>                 if (irq <= 0) {
>>                         ret = irq ? irq : -ENXIO;
> 
> irq == 0 cannot happen.
> 
>>                         goto out_unregister;
>>                 }

Sorry, I don't get the two comments. May be I missed something but it
seems for me the results are the same with the inverted conditions or not.

if (irq <= 0 && irq != -ENXIO)
	goto out;

if (irq == -ENXIO)
	continue;

Can be changed to:

if (irq != -ENXIO)
	if (irq <= 0)
		goto out;

if (irq == -ENXIO)
	continue;

Can be changed to:


if (irq == -ENXIO)
	continue;

if (irq != -ENXIO)
	if (irq <= 0)
		goto out;

The second condition is always true because the first condition is the
opposite of the second condition, if the second condition block is
reached, that means irq != -ENXIO, so we can remove the second condition
and that results into:

if (irq == -ENXIO)
	continue;

if (irq <= 0)
	goto out;


Did I miss your point ?


> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
> 


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