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Message-ID: <461057.78283.qm@web180310.mail.gq1.yahoo.com>
Date: Sat, 28 Aug 2010 16:18:51 -0700 (PDT)
From: David Brownell <david-b@pacbell.net>
Subject: Re: [PATCH] GPIO: add support for NXP 74HC164 GPIO expander
To: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
        Samuel Ortiz <sameo@linux.intel.com>,
        Miguel Gaio <miguel.gaio@efixo.com>, Juhos Gabor <juhosg@openwrt.org>,
        David Brownell <dbrownell@users.sourceforge.net>,
        Florian Fainelli <florian@openwrt.org>
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--- On Sat, 8/28/10, Florian Fainelli <florian@openwrt.org> wrote:

> This patch adds support for
> NXP's 74HC164 GPIO expander.

The 74164 parts are standard 74xxx series
discrete logic parts sold by many vendors
as 8 bit shift registers ... and in many
logic series (HC, HCT, more).

At least describe this as generic to all
those 8-bit shift registers, not just NXP.
And not as "GPIO expanders"; data sheets
describe them as shift registers.  Kconfig
can say that the shift registers are being
used for GPIO (output) expansion.

I suppose it's reasonable not to support the
way these chips can be daisy-chained, but it'd
be worth a comment, IMO; that strikes me as a
think someone will add at some point, via some
platform data (e.g.32 GPIO outputs from 4 chips).

- Dave

p.s. I'd have to pull out my data sheet collection
to verify, but it might be the 74163 which can
be used as an 8 bit parallel to serial (input)
 shift register...


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