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Message-ID: <1432825060.8508.57.camel@x220>
Subject: Re: [PATCH 4/5] kconfig: Introduce "showif" to factor out
 conditions on visibility
From: Paul Bolle <pebolle@tiscali.nl>
To: josh@joshtriplett.org
Cc: Ingo Molnar <mingo@kernel.org>, Andrew Morton <akpm@linux-foundation.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
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        Pranith Kumar <bobby.prani@gmail.com>,
        Clark Williams <clark.williams@gmail.com>,
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Date: Thu, 28 May 2015 16:57:40 +0200
In-Reply-To: <20150520183042.GA5720@cloud>
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On Wed, 2015-05-20 at 11:30 -0700, josh@joshtriplett.org wrote:
> In net/rfkill/Kconfig, RFKILL_REGULATOR oddly has
> "depends on RFKILL || !RFKILL".  WIMAX does the same thing.

That's only tristate logic. It's a common idiom, but it looks very odd
compared to boolean logic. It ensures RFKILL_REGULATOR will not be 'y'
if RFKILL is 'm'. Because:
    RFKILL = 'n' => RFKILL_REGULATOR = 'n' || 'm' || 'y'
    RFKILL = 'm' => RFKILL_REGULATOR = 'n' || 'm'
    RFKILL = 'y' => RFKILL_REGULATOR = 'n' || 'm' || 'y'

Hope this helps,


Paul Bolle