linux-kernel - Re: [PATCH V2 2/3] gpio: xilinx: Add interrupt support

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Date:   Fri, 24 Jul 2020 22:58:56 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Srinivas Neeli <sneeli@...inx.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Michal Simek <michals@...inx.com>,
        Shubhrajyoti Datta <shubhraj@...inx.com>,
        Srinivas Goud <sgoud@...inx.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        git <git@...inx.com>, Robert Hancock <hancock@...systems.ca>
Subject: Re: [PATCH V2 2/3] gpio: xilinx: Add interrupt support

On Fri, Jul 24, 2020 at 8:15 PM Srinivas Neeli <sneeli@...inx.com> wrote:

...

> > > +#include <linux/irqchip/chained_irq.h>
> >
> > Not sure I see a user of it.
> >
> > ...
> we are using chained_irq_enter() and chained_irq_exit()
> APIs , so need "chained_irq.h"

I see.  But gpio/driver.h does it for you.

...

> > > +       for (index = 0; index < num_channels; index++) {
> > > +               if ((status & BIT(index))) {
> >
> > If gpio_width is the same among banks, you can use for_each_set_bit()
> > here as well.
> >
> > ...
> gpio_wdith vary depends on design. We can configure gpio pins for each bank.

I see.

...

> > > +       chip->irq = platform_get_irq_optional(pdev, 0);
> > > +       if (chip->irq <= 0) {
> > > +               dev_info(&pdev->dev, "GPIO IRQ not set\n");
> >
> > Why do you need an optional variant if you print an error anyway?
>
> Here intention is just printing a debug message to user.

Debug message should be debug, and not info. But in any case, I would
rather drop it, or use platform_get_irq() b/c now you have a code
controversy.

...

> > > +               chip->gc.irq.parents = (unsigned int *)&chip->irq;
> > > +               chip->gc.irq.num_parents = 1;
> >
> > Current pattern is to use devm_kcalloc() for it (Linus has plans to
> > simplify this in the future and this will help him to find what
> > patterns are being used)
>
> I didn't get this , Could you please explain more.

              girq->num_parents = 1;
              girq->parents = devm_kcalloc(dev, girq->num_parents, ...);
   if (!girq->parents)
     return -ENOMEM;

girq->parents[0] = chip->irq;

Also, use temporary variable for IRQ chip structure:
 girq = &chip->gc.irq;


-- 
With Best Regards,
Andy Shevchenko