linux-kernel - Re: [PATCH linux v1 0/4] Seven segment display support

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Message-ID: <20161214134530.2bd54a4e@free-electrons.com>
Date:   Wed, 14 Dec 2016 13:45:30 +0100
From:   Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
To:     Jaghathiswari Rankappagounder Natarajan <jaghu@...gle.com>
Cc:     openbmc@...ts.ozlabs.org, robh+dt@...nel.org, mark.rutland@....com,
        linux@...linux.org.uk, arnd@...db.de, gregkh@...uxfoundation.org,
        joel@....id.au, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org
Subject: Re: [PATCH linux v1 0/4] Seven segment display support

Hello,

On Tue, 13 Dec 2016 23:55:00 -0800, Jaghathiswari Rankappagounder
Natarajan wrote:

> Documentation for the binding which provides an interface for adding clock,
> data and clear signal GPIO lines to control seven segment display.
> 
> The platform device driver provides an API for displaying on two 7-segment
> displays, and implements the required bit-banging. The hardware assumed is
> 74HC164 wired to two 7-segment displays.
> 
> The character device driver implements the user-space API for letting a user
> write to two 7-segment displays including any conversion methods necessary
> to map the user input to two 7-segment displays.
> 
> Adding clock, data and clear signal GPIO lines in the devicetree to control
> seven segment display on zaius platform.
> 
> The platform driver matches on the device tree node; the platform driver also
> initializes the character device.
> 
> Tested that the seven segment display works properly by writing to the
> character device file on a EVB AST2500 board which also has 74HC164 wired
> to two 7-segment displays.

FWIW, I proposed a driver for seven segment displays back in 2013:

   http://lists.infradead.org/pipermail/linux-arm-kernel/2013-January/139986.html

And the feedback from Greg KH was: we don't need a driver for that, do
it from userspace. See:

   http://lists.infradead.org/pipermail/linux-arm-kernel/2013-January/139992.html

So: good luck :-)

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com