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Date: Thu, 24 Sep 2015 11:43:24 +0300
From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Olliver Schinagl <oliver+list@schinagl.nl>
Cc: Linus Walleij <linus.walleij@linaro.org>,
        Grant Likely <grant.likely@linaro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        Alexandre Courbot <gnurou@gmail.com>, linux-gpio@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: gpios search behaviour for gpio from _DSD
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References: <5603A552.9020005@schinagl.nl>
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On Thu, Sep 24, 2015 at 09:25:06AM +0200, Olliver Schinagl wrote:
> Hey list, Mika,
> 
> With commit 0d9a693cc86 the following snippet of code was added:
> 
> +       /* Try first from _DSD */
> +       for (i = 0; i < ARRAY_SIZE(suffixes); i++) {
> +               if (con_id && strcmp(con_id, "gpios")) {
> +                       snprintf(propname, sizeof(propname), "%s-%s",
> +                                con_id, suffixes[i]);
> 
> and I was wondering why the gpios suffix is singled out. Are we not allowed
> to check for all the strings in the suffixes array? Is gpios special or is
> gpio simply not allowed. If that strcmp check would be removed, would bad
> things happen?

We default to "gpios". So if you pass "reset" we actually look for
proprerty "reset-gpios". This is the recommend syntax AFAIK.

> Also, just to educate myself, isn't relying on left to right parsing
> complier specifc? E.g. if con_id is null, we end up passing NULL to strcmp
> and atleast for libc can cause segfaults iirc.

'&&' is so called short circuit operator so if we already know that
con_id is NULL we never evaluate the remaining conditions.