linux-kernel - Re: [PATCH] gpiolib: Don't implicitly disable irq when masking

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Date:   Wed, 10 May 2023 10:42:20 +0300
From:   andy.shevchenko@...il.com
To:     Chris Packham <chris.packham@...iedtelesis.co.nz>
Cc:     linus.walleij@...aro.org, brgl@...ev.pl, mkshah@...eaurora.org,
        Ben Brown <ben.brown@...iedtelesis.co.nz>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpiolib: Don't implicitly disable irq when masking

Wed, May 10, 2023 at 12:11:51PM +1200, Chris Packham kirjoitti:
> When preparing to kexec into a new kernel the kexec code will mask all
> interrupts for all interrupt domains before disabling them. In the case
> of a gpio chip which has a mix of gpio and irq pins a warning would be
> triggered as follows

>   [root@...alhost ~]# echo c >/proc/sysrq-trigger

Besides the very noisy traceback in the commit message (read
https://kernel.org/doc/html/latest/process/submitting-patches.html#backtraces-in-commit-messages)
see below.

> This is because gpiochip_irq_mask was being used to mask all possible

We refer to the functions in the form as follows gpiochip_irq_mask().


> irqs in the domain but gpiochip_disable_irq will WARN if any of those

IRQs
gpiochip_disable_irq()

> gpios haven't been requested as interrupts yet. Remove the call to

GPIOs

> gpiochip_disable_irq to stop the warning.

gpiochip_disable_irq()

> Fixes: a8173820f441 ("gpio: gpiolib: Allow GPIO IRQs to lazy disable")
> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
> ---
>  drivers/gpio/gpiolib.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 8c041a8dd9d8..903f5185ae55 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1451,7 +1451,6 @@ static void gpiochip_irq_mask(struct irq_data *d)
>  
>  	if (gc->irq.irq_mask)
>  		gc->irq.irq_mask(d);
> -	gpiochip_disable_irq(gc, d->hwirq);
>  }

At the same time the gpiochip_irq_unmask() has the symmetrical call. Why?

Also it's obvious that you have used outdated repository. You need to rebase
against subsystem tree for-next branch.

P.S. It's also makes sense to Cc to Marc Zyngier <maz@...nel.org>.

-- 
With Best Regards,
Andy Shevchenko