linux-kernel - Re: [PATCH 2/2] gpio: sch: Add interrupt support

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Date:   Fri, 26 Apr 2019 20:44:36 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     Jan Kiszka <jan.kiszka@...mens.com>,
        "Enrico Weigelt, metux IT consult" <lkml@...ux.net>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH 2/2] gpio: sch: Add interrupt support

On Fri, Apr 26, 2019 at 8:33 PM Manivannan Sadhasivam
<manivannan.sadhasivam@...aro.org> wrote:
> On Fri, Apr 26, 2019 at 08:20:19PM +0300, Andy Shevchenko wrote:
> > On Fri, Apr 26, 2019 at 7:05 PM Jan Kiszka <jan.kiszka@...mens.com> wrote:
> > > On 26.04.19 16:42, Enrico Weigelt, metux IT consult wrote:
> > > > On 26.04.19 15:36, Jan Kiszka wrote:

> > The problem here is opaque number. This has to be chip + *relative* pin number/
> > See this:
> > https://stackoverflow.com/questions/55532410/how-do-linux-gpio-numbers-get-their-values/55579640#55579640
> >
>
> But for platform like 96Boards we don't need controller specific lookup, these
> are all handled by the platform code [1] so that the users can use the standard
> pinout number to access GPIOs.

This is a complete mistake.

There is *no* global GPIO numbers anymore in Linux. (I don't count
very old legacy platforms)
Read above, it applies to DT or whatever resource provider.

> For instance, pin 23 on the Low Speed expansion
> header is the GPIO for all 96Boards platform, so the user can access that pin
> using 23 itself in the application and it will run across all supported
> 96Boards.
>
> That's one of the reason why we prefer MRAA.

> [1] https://github.com/intel-iot-devkit/mraa/blob/master/src/arm/96boards.c#L75

-- 
With Best Regards,
Andy Shevchenko