linux-kernel - Re: [PATCH v6 3/3] mmc: atmel-mci: Move card detect gpio polarity quirk to gpiolib

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Message-ID: <CACRpkdahEcKgR9gR7iU0cW_aDTReDYBKdP+5_F+hGcarCjG9gg@mail.gmail.com>
Date:   Fri, 25 Aug 2023 13:45:20 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Balamanikandan Gunasundar 
        <balamanikandan.gunasundar@...rochip.com>
Cc:     dmitry.torokhov@...il.com, ulf.hansson@...aro.org,
        linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        ludovic.desroches@...rochip.com, nicolas.ferre@...rochip.com,
        alexandre.belloni@...tlin.com, hari.prasathge@...rochip.com
Subject: Re: [PATCH v6 3/3] mmc: atmel-mci: Move card detect gpio polarity
 quirk to gpiolib

On Fri, Aug 25, 2023 at 11:53 AM Balamanikandan Gunasundar
<balamanikandan.gunasundar@...rochip.com> wrote:

> The polarity of the card detection gpio is handled by the "cd-inverted"
> property in the device tree. Move this inversion logic to gpiolib to avoid
> reading the gpio raw value.
>
> Signed-off-by: Balamanikandan Gunasundar <balamanikandan.gunasundar@...rochip.com>
> Suggested-by: Linus Walleij <linus.walleij@...aro.org>

Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

> +#if IS_ENABLED(CONFIG_MMC_ATMELMCI)
> +       /*
> +        * The Atmel HSMCI has compatible property in the parent node and
> +        * gpio property in a child node
> +        */
> +       if (of_device_is_compatible(np->parent, "atmel,hsmci")) {
> +               np_compat = np->parent;
> +               np_propname = np;
> +       }
> +#endif

You don't need to use the preprocessor actually, what I did in my
example works:

if (IS_ENABLED()... && of_device_is_compatible()...) {
...
}

If the first expression in the if() clause is constant false, the compiler
will optimize out the entire if()-clause. At least the compilers we care
about.

Yours,
Linus Walleij