linux-kernel - [PATCH 0/1] auxdisplay: Add I2C gpio expander example

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Message-ID: <20210106113730.k5qveshjgcd57kgx@runtux.com>
Date:   Wed, 6 Jan 2021 12:37:30 +0100
From:   Ralf Schlatterbeck <rsc@...tux.com>
To:     linux-kernel <linux-kernel@...r.kernel.org>,
        Willy Tarreau <w@....eu>, Lars Poeschel <poeschel@...onage.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Subject: [PATCH 0/1] auxdisplay: Add I2C gpio expander example

The Hitachi HD44780 is often used together with a PCF8574 based I2C
I/O expander. It was non-obvious to me that the existing parallel
connected version of the auxdisplay driver can already handle this
configuration with appropriate device tree magic. This patch documents
the necessary incantations in an example.

That this is not only non-obvious to me is documented by at least two
I2C kernel implementations for the display out there.

Thanks to Geert Uytterhoeven for pointing out how this is done.
Thanks to Miguel Ojeda for extensively commenting on my previous patch.

 .../bindings/auxdisplay/hit,hd44780.yaml      | 31 ++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

Ralf
-- 
Ralf Schlatterbeck                      Tel:   +43/2243/26465-16
Open Source Consulting                  www:   www.runtux.com
Reichergasse 131, A-3411 Weidling       email: office@...tux.com