linux-kernel - Re: [PATCH v1 1/1] pinctrl: core: Show pin numbers for the controllers with base = 0

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Message-ID: <YH6ojEvp6m3g2Ihx@smile.fi.intel.com>
Date:   Tue, 20 Apr 2021 13:10:20 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Drew Fustini <drew@...gleboard.org>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] pinctrl: core: Show pin numbers for the
 controllers with base = 0

On Tue, Apr 20, 2021 at 12:32:18AM -0700, Drew Fustini wrote:
> On Thu, Apr 15, 2021 at 04:03:56PM +0300, Andy Shevchenko wrote:
> > The commit f1b206cf7c57 ("pinctrl: core: print gpio in pins debugfs file")
> > enabled GPIO pin number and label in debugfs for pin controller. However,
> > it limited that feature to the chips where base is positive number. This,
> > in particular, excluded chips where base is 0 for the historical or backward
> > compatibility reasons. Refactor the code to include the latter as well.

...

> > -		chip = gpio_to_chip(gpio_num);
> > -		if (chip && chip->gpiodev && chip->gpiodev->base)
> > -			seq_printf(s, "%u:%s ", gpio_num -
> > -				chip->gpiodev->base, chip->label);
> > +		if (gpio_num >= 0)
> > +			chip = gpio_to_chip(gpio_num);
> > +		else
> > +			chip = NULL;
> > +		if (chip)
> > +			seq_printf(s, "%u:%s ", gpio_num - chip->gpiodev->base, chip->label);
> >  		else
> >  			seq_puts(s, "0:? ");

> Thank you, this makes sense to me. I had failed to consider what would
> happen when chip->gpiodev->base == 0.

If gpiodev->base == 0 it can happen only when
1) either base is 0 by the driver request
2) or it's a GPIO device which fits the (last) free slot in the number space

It can't be negative at all. So, it means whatever value is there it is always
valid.

> I have tested on the BeagleBone
> (AM3358) and the output works as expected.

Cool!

> /sys/kernel/debug/pinctrl/44e10800.pinmux-pinctrl-single# more pins
> registered pins: 142
> pin 0 (PIN0) 0:gpio-0-31 44e10800 00000027 pinctrl-single
> pin 1 (PIN1) 1:gpio-0-31 44e10804 00000027 pinctrl-single
> pin 2 (PIN2) 2:gpio-0-31 44e10808 00000027 pinctrl-single
> pin 3 (PIN3) 3:gpio-0-31 44e1080c 00000027 pinctrl-single
> pin 4 (PIN4) 4:gpio-0-31 44e10810 00000027 pinctrl-single
> pin 5 (PIN5) 5:gpio-0-31 44e10814 00000027 pinctrl-single
> pin 6 (PIN6) 6:gpio-0-31 44e10818 00000027 pinctrl-single
> pin 7 (PIN7) 7:gpio-0-31 44e1081c 00000027 pinctrl-single
> pin 8 (PIN8) 22:gpio-96-127 44e10820 00000027 pinctrl-single
> pin 9 (PIN9) 23:gpio-96-127 44e10824 00000037 pinctrl-single
> pin 10 (PIN10) 26:gpio-96-127 44e10828 00000037 pinctrl-single
> pin 11 (PIN11) 27:gpio-96-127 44e1082c 00000037 pinctrl-single
> pin 12 (PIN12) 12:gpio-0-31 44e10830 00000037 pinctrl-single
> pin 13 (PIN13) 13:gpio-0-31 44e10834 00000037 pinctrl-single
> pin 14 (PIN14) 14:gpio-0-31 44e10838 00000037 pinctrl-single
> pin 15 (PIN15) 15:gpio-0-31 44e1083c 00000037 pinctrl-single
> pin 16 (PIN16) 16:gpio-0-31 44e10840 00000027 pinctrl-single
> <snip>
> 
> Tested-by: Drew Fustini <drew@...gleboard.org>
> Reviewed-by: Drew Fustini <drew@...gleboard.org>

Thank you!

Linus, can it be applied now?

-- 
With Best Regards,
Andy Shevchenko