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From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH] gpio: add driver for SN74273 output expander
Date: Tue, 17 Sep 2019 11:22:19 +0200	[thread overview]
Message-ID: <0f039d89-2b64-ae91-a0c3-30c10c461c34@pengutronix.de> (raw)
In-Reply-To: <20190909072331.4xmc6nvjgfdxged3@pengutronix.de>

On 9/9/19 9:23 AM, Sascha Hauer wrote:
> On Fri, Sep 06, 2019 at 04:01:27PM +0200, Ahmad Fatoum wrote:
>> The SN74273 is an octal D-Type Flip-Flop. When used as an output expander,
>> N existing output signals can be turned into (N-8)*8 outputs using
>> N-8 chips. Add driver to facilitate this.
> 
> The reason I haven't mainlined this driver when writing it was that
> Linux also has a driver for the 74273, but in a completely different
> setup. In the Linux driver the 74273 is assumed to have its inputs on
> the data bus together with a separate address decoder.
> The chip in this driver here instead is connected via GPIO pins. For
> Using flipflops as GPIO expanders there a myriads of different ways to
> implement, so I have my doubts how useful it is to even try to put them
> in a generic driver.

FTR: I talked this over with Sascha. As I understood, the main issue is
with reserving a fairly generic "ti,74273-gpio" compatible with what is
a very special way of using these flip flops. We could however get it in
with a different proprietary compatible. I might revisit this in future
along with a kernel driver, but please dismiss for now.


> 
> Sascha
> 

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      reply	other threads:[~2019-09-17  9:22 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-06 14:01 Ahmad Fatoum
2019-09-09  7:23 ` Sascha Hauer
2019-09-17  9:22   ` Ahmad Fatoum [this message]

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