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Date:   Fri, 24 Nov 2023 13:35:05 +0900
From:   Youngmin Nam <youngmin.nam@samsung.com>
To:     Sam Protsenko <semen.protsenko@linaro.org>
Cc:     tomasz.figa@gmail.com, krzysztof.kozlowski@linaro.org,
        s.nawrocki@samsung.com, alim.akhtar@samsung.com,
        linus.walleij@linaro.org, linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org, linux-gpio@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] pinctrl: samsung: add irq_set_affinity() for non wake
 up external gpio interrupt
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References: <CGME20231119085440epcas2p375fa3b2999e1a3ceeff9949136db7e28@epcas2p3.samsung.com>
        <20231119092909.3018578-1-youngmin.nam@samsung.com>
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On Tue, Nov 21, 2023 at 12:33:51PM -0600, Sam Protsenko wrote:
> On Sun, Nov 19, 2023 at 2:54 AM Youngmin Nam <youngmin.nam@samsung.com> wrote:
> >
> > To support affinity setting for non wake up external gpio interrupt,
> > we add a new irq_set_affinity callback using irq number which is in pinctrl
> > driver data.
> >
> > Before applying this patch, we couldn't change irq affinity of gpio interrupt.
> > * before
> > erd9945:/proc/irq/418 # cat smp_affinity
> > 3ff
> > erd9945:/proc/irq/418 # echo 00f > smp_affinity
> > erd9945:/proc/irq/418 # cat smp_affinity
> > 3ff
> > erd9945:/proc/irq/418 # cat /proc/interrupts
> >            CPU0       CPU1       CPU2       CPU3       CPU4       CPU5       CPU6       CPU7       CPU8       CPU9
> > 418:       3631          0          0          0          0          0          0          0          0          0      gpg2   0 Edge      19100000.drmdecon
> >
> > After applying this patch, we can change irq affinity of gpio interrupt as below.
> > * after
> > erd9945:/proc/irq/418 # cat smp_affinity
> > 3ff
> > erd9945:/proc/irq/418 # echo 00f > smp_affinity
> > erd9945:/proc/irq/418 # cat smp_affinity
> > 00f
> > erd9945:/proc/irq/418 # cat /proc/interrupts
> >            CPU0       CPU1       CPU2       CPU3       CPU4       CPU5       CPU6       CPU7       CPU8       CPU9
> > 418:       3893        201        181        188          0          0          0          0          0          0      gpg2   0 Edge      19100000.drmdecon
> >
> 
> Suggest formatting the commit message as follows, to make it more readable:
> 
> 8<-------------------------------------------------------------------------->8
> To support affinity setting for non wake up external gpio interrupt,
> add irq_set_affinity callback using irq number from pinctrl driver
> data.
> 
> Before this patch, changing the irq affinity of gpio interrupt is not
> possible:
> 
>     # cat /proc/irq/418/smp_affinity
>     3ff
>     # echo 00f > /proc/irq/418/smp_affinity
>     # cat /proc/irq/418/smp_affinity
>     3ff
>     # cat /proc/interrupts
>                CPU0       CPU1       CPU2       CPU3    ...
>     418:       3631          0          0          0    ...
> 
> With this patch applied, it's possible to change irq affinity of gpio
> interrupt:
> 
>     # cat /proc/irq/418/smp_affinity
>     3ff
>     # echo 00f > /proc/irq/418/smp_affinity
>     # cat /proc/irq/418/smp_affinity
>     00f
>     # cat /proc/interrupts
>                CPU0       CPU1       CPU2       CPU3      ...
>     418:       3893        201        181        188      ...
> 8<-------------------------------------------------------------------------->8
> 

Thanks for your suggestion. I'll modify it.

> > Signed-off-by: Youngmin Nam <youngmin.nam@samsung.com>
> > ---
> >  drivers/pinctrl/samsung/pinctrl-exynos.c | 14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/pinctrl/samsung/pinctrl-exynos.c b/drivers/pinctrl/samsung/pinctrl-exynos.c
> > index 6b58ec84e34b..5d7b788282e9 100644
> > --- a/drivers/pinctrl/samsung/pinctrl-exynos.c
> > +++ b/drivers/pinctrl/samsung/pinctrl-exynos.c
> > @@ -147,6 +147,19 @@ static int exynos_irq_set_type(struct irq_data *irqd, unsigned int type)
> >         return 0;
> >  }
> >
> > +static int exynos_irq_set_affinity(struct irq_data *irqd,
> > +                                  const struct cpumask *dest, bool force)
> > +{
> > +       struct samsung_pin_bank *bank = irq_data_get_irq_chip_data(irqd);
> > +       struct samsung_pinctrl_drv_data *d = bank->drvdata;
> > +       struct irq_data *parent = irq_get_irq_data(d->irq);
> 
> I'm probably missing something, but: why not just use "irqd" parameter
> and avoid declaring "bank" and "d"? Is "d->irq" somehow different from
> "irqd"?
> 

Yes, irqd->irq is different from d->irq as below.

[  188.230707] irqd->irq is 417
[  188.230837] d->irq is 133

We have to use d->irq(133) instead of irqd->irq(417) because d->irq has GICv3 as a IRQ chip.
To use set_affinity() call back of GICv3, d->irq is needed.

IRQ  HWIRQ  Type   Affinity    IRQ_DESC             CPU0    CPU1    CPU2    CPU3 ... Chip   Name
133    603  Level  0x3ff       0xffffff883b25d800  52260       0       0       0 ... GICv3  11030000.pinctrl
417      0  Edge   0xffffffff  0xffffff883b68a800  52259       0       0       0 ... gpg2   19100000.drmdecon

erd9945: # cat /proc/interrupts | grep gpg2
417:       9250         48         45         45 ...  gpg2   0 Edge      19100000.drmdecon

erd9945: # cat /proc/interrupts | grep 11030000
133:       9250         48         45         45 ...  GICv3 603 Level     11030000.pinctrl

> > +
> > +       if (parent)
> > +               return parent->chip->irq_set_affinity(parent, dest, force);
> > +
> 
> Why not use irq_chip_set_affinity_parent() API?
> 
> > +       return -EINVAL;
> 
> Maybe use something like this instead:
> 
>     if (!irqd->parent_data)
>             return -EINVAL;
> 
>     return irq_chip_set_affinity_parent(irqd, dest, force);
> 
> Can you please test if this code works?
> 

I tested as you suggested as below.

diff --git a/drivers/pinctrl/samsung/pinctrl-exynos.c b/drivers/pinctrl/samsung/pinctrl-exynos.c
index bf8dd5e3c3d2..593320b408ce 100644
--- a/drivers/pinctrl/samsung/pinctrl-exynos.c
+++ b/drivers/pinctrl/samsung/pinctrl-exynos.c
@@ -153,14 +153,12 @@ static int exynos_irq_set_type(struct irq_data *irqd, unsigned int type)
 static int exynos_irq_set_affinity(struct irq_data *irqd,
                                   const struct cpumask *dest, bool force)
 {
-       struct samsung_pin_bank *bank = irq_data_get_irq_chip_data(irqd);
-       struct samsung_pinctrl_drv_data *d = bank->drvdata;
-       struct irq_data *parent = irq_get_irq_data(d->irq);
-
-       if (parent)
-               return parent->chip->irq_set_affinity(parent, dest, force);
+       if (!irqd->parent_data) {
+               pr_err("irqd->parent_data is null!!\n");
+               return -EINVAL;
+       }

-       return -EINVAL;
+       return irq_chip_set_affinity_parent(irqd, dest, force);
 }

[  149.658395] irqd->parent_data is null!!

Currently, irqd->paranet_data is null.

> > +}
> > +
> >  static int exynos_irq_request_resources(struct irq_data *irqd)
> >  {
> >         struct samsung_pin_bank *bank = irq_data_get_irq_chip_data(irqd);
> > @@ -212,6 +225,7 @@ static const struct exynos_irq_chip exynos_gpio_irq_chip __initconst = {
> >                 .irq_mask = exynos_irq_mask,
> >                 .irq_ack = exynos_irq_ack,
> >                 .irq_set_type = exynos_irq_set_type,
> > +               .irq_set_affinity = exynos_irq_set_affinity,
> 
> What happens if we just assign irq_chip_set_affinity_parent() here?
> Would it work, or Exynos case is more complicated than this?
> 

Yes, I couldn't find how to use irq_chip_set_affinity_parent() directly yet.

> >                 .irq_request_resources = exynos_irq_request_resources,
> >                 .irq_release_resources = exynos_irq_release_resources,
> >         },
> > --
> > 2.39.2
> >
> 

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