linux-kernel - Re: [PATCH v5 3/3] gpiolib: Show correct direction from the beginning

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Message-ID: <CAOZdJXUgFS+f6P5TFfh2s==fT3jEi8tAnJLX+uQJvFpzfOpDjA@mail.gmail.com>
Date:   Fri, 5 Oct 2018 15:44:06 -0500
From:   Timur Tabi <timur@...nel.org>
To:     Timur Tabi <timur@...nel.org>
Cc:     Jeffrey Hugo <jhugo@...eaurora.org>,
        Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>,
        Linus <linus.walleij@...aro.org>,
        Stephen Boyd <swboyd@...omium.org>,
        linux-gpio <linux-gpio@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 3/3] gpiolib: Show correct direction from the beginning

On Fri, Oct 5, 2018 at 11:54 AM Timur Tabi <timur@...nel.org> wrote:
> If you want, just put a printk(... offset) in msm_gpio_get() and read
> from a GPIO that you know you have access to, and make sure the
> 'offset' is correct.
>
> Then try reading from a GPIO that you don't have access to, and make
> sure you get a failure before msm_gpio_get() is called.

Just FYI, if you use sysfs to write to the GPIO, based on the kernel
log you pasted, GPIO 362 in sysfs is actually pin 0 in the TLMM.

If you use gpio-test, it uses gpiolib which figures this all out for
you.  There should still be the gpio-test wiki page I wrote that tells
you how to use it.