linux-kernel - Re: [PATCH 2/2] pinctrl: Add Intel Keem Bay pinctrl driver

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Date:   Fri, 28 May 2021 10:21:15 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     "D, Lakshmi Sowjanya" <lakshmi.sowjanya.d@...el.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "Raja Subramanian, Lakshmi Bai" 
        <lakshmi.bai.raja.subramanian@...el.com>,
        "Saha, Tamal" <tamal.saha@...el.com>
Subject: Re: [PATCH 2/2] pinctrl: Add Intel Keem Bay pinctrl driver

On Thu, May 27, 2021 at 4:44 PM D, Lakshmi Sowjanya
<lakshmi.sowjanya.d@...el.com> wrote:
> From: Linus Walleij <linus.walleij@...aro.org>

> > > +       val |= FIELD_PREP(KEEMBAY_GPIO_MODE_INV_MASK, KEEMBAY_GPIO_MODE_INV_VAL);
> > > +       keembay_write_reg(val, kpc->base1 + KEEMBAY_GPIO_MODE, pin); }
>
> > Why would you want to invert? OK I guess I read and see..
>
> The IP doesn't support the falling edge and low level interrupt trigger. Hence
> the invert API is used to mimic the falling edge and low level support.

That is a clever hack.

Write some comments about that here or at the call sites so it is
clear what is going on and why you are doing this, so readers
of the code understand.

Yours,
Linus Walleij