linux-kernel - Re: [PATCH v5 02/10] pinctrl: generic: Add macros to unpack properties

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Date:   Fri, 28 Apr 2017 10:16:22 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Jacopo Mondi <jacopo+renesas@...ndi.org>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Chris Brandt <chris.brandt@...esas.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 02/10] pinctrl: generic: Add macros to unpack properties

On Thu, Apr 27, 2017 at 10:19 AM, Jacopo Mondi
<jacopo+renesas@...ndi.org> wrote:

> Add PIN_CONF_UNPACK_PARAM and PIN_CONF_UNPACK_ARGS macros useful to
> unpack generic properties and their arguments
>
> Signed-off-by: Jacopo Mondi <jacopo+renesas@...ndi.org>

(...)

/*
  * Helpful configuration macro to be used in tables etc.

Then this should say "macros" rather than "macro".

> -#define PIN_CONF_PACKED(p, a) ((a << 8) | ((unsigned long) p & 0xffUL))
> +#define PIN_CONF_PACKED(p, a) (((a) << 8) | ((unsigned long) (p) & 0xffUL))

Also adding some extra parantheses I see.

> +#define PIN_CONF_UNPACK_PARAM(c) ((c) & 0xffUL)
> +#define PIN_CONF_UNPACK_ARGS(c) ((c) >> 8)

But why.

I have these two static inlines just below your new macros:

static inline enum pin_config_param pinconf_to_config_param(unsigned
long config)
{
        return (enum pin_config_param) (config & 0xffUL);
}

static inline u32 pinconf_to_config_argument(unsigned long config)
{
        return (u32) ((config >> 8) & 0xffffffUL);
}

Why can't you use this in your code instead of macros?

We generally prefer static inlines over macros because they are easier
to read.

Yours,
Linus Walleij