linux-kernel - Re: [PATCH v2 2/2] pinctrl: iproc: use unique name for irq chip

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Date:   Mon, 7 Oct 2019 10:10:52 -0700
From:   Scott Branden <scott.branden@...adcom.com>
To:     Marc Zyngier <maz@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Chris Packham <chris.packham@...iedtelesis.co.nz>,
        Linus Walleij <linus.walleij@...aro.org>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com,
        rayagonda.kokatanur@...adcom.com, li.jin@...adcom.com,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 2/2] pinctrl: iproc: use unique name for irq chip



On 2019-10-07 1:14 a.m., Marc Zyngier wrote:
> On Mon, 07 Oct 2019 08:30:50 +0100,
> Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>> Hi Chris,
>>
>> CC MarcZ
>>
>> On Thu, Oct 3, 2019 at 2:03 AM Chris Packham
>> <chris.packham@...iedtelesis.co.nz> wrote:
>>> Use the dev_name(dev) for the irqc->name so that we get unique names
>>> when we have multiple instances of this driver.
>>>
>>> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
>> A while ago, Marc Zyngier pointed out that the irq_chip .name field
>> should contain the device's class name, not the instance's name.
>> Hence the current code is correct?
> Thanks Geert for looping me in. The main reasons why I oppose this
> kind of "let's show as much information as we can in /proc/interrupts"
> are:
>
> - It clutters the output badly: the formatting of this file, which is
>    bad enough when you have a small number of CPUs, becomes unreadable
>    when you have a large number of them *and* stupidly long strings
>    that only make sense on a given platform.
>
> - Like it or not, /proc is ABI. We don't change things randomly there
>    without a good reason, and debugging isn't one of them.
>
> - Debug information belongs to debugfs, where we already have plenty
>    of stuff (see CONFIG_GENERIC_IRQ_DEBUGFS). I'd rather we improve
>    this infrastructure if needed, rather than add platform specific
>    hacks.
>
> </rant>
>
> Thanks,
>
> 	M.
Thanks Marc/Geert.  Sounds like we should drop patch 2 from series.
>
>> See also "[PATCH 0/4] irqchip: renesas: Use proper irq_chip name and parent"
>> (https://lore.kernel.org/lkml/20190607095858.10028-1-geert+renesas@glider.be/)
>> Note that the irqchip patches in that series have been applied; the gpio
>> patches haven't been applied yet.
>>
>>> --- a/drivers/pinctrl/bcm/pinctrl-iproc-gpio.c
>>> +++ b/drivers/pinctrl/bcm/pinctrl-iproc-gpio.c
>>> @@ -858,7 +858,7 @@ static int iproc_gpio_probe(struct platform_device *pdev)
>>>                  struct gpio_irq_chip *girq;
>>>
>>>                  irqc = &chip->irqchip;
>>> -               irqc->name = "bcm-iproc-gpio";
>>> +               irqc->name = dev_name(dev);
>>>                  irqc->irq_ack = iproc_gpio_irq_ack;
>>>                  irqc->irq_mask = iproc_gpio_irq_mask;
>>>                  irqc->irq_unmask = iproc_gpio_irq_unmask;
>> Gr{oetje,eeting}s,
>>
>>                          Geert
>>
>> -- 
>> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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
>>