Received-SPF: pass (google.com: domain of linux-kernel+bounces-72527-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Date: Tue, 20 Feb 2024 08:18:42 +0000
From: Lee Jones <lee@kernel.org>
To: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
Cc: Pavel Machek <pavel@ucw.cz>,
	"linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Linux support for a 7 segment LED display
Message-ID: <20240220081842.GF10170@google.com>
References: <1f598a72-dd9f-4c6c-af7f-29751f84bd23@alliedtelesis.co.nz>
 <20240219151332.GC10170@google.com>
 <a70425d3-95be-4360-9828-d5403404e803@alliedtelesis.co.nz>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <a70425d3-95be-4360-9828-d5403404e803@alliedtelesis.co.nz>

On Mon, 19 Feb 2024, Chris Packham wrote:

> Hi Lee,
> 
> On 20/02/24 04:13, Lee Jones wrote:
> > On Sun, 11 Feb 2024, Chris Packham wrote:
> >
> >> Hi Blinkenlight enthusiasts,
> >>
> >> I'm looking for something that I figured must exists but maybe it's so
> >> niche that no-one has bothered to upstream a driver for it.
> >>
> >> I have a requirement to support a 7-segment LED display[1] (one that can
> >> display a single digit from 0-9). Hardware wise it's just a bunch of
> >> individual GPIOs connected to each segment (plus an extra one for a
> >> dot). I can't see anything obvious in drivers/leds but maybe I'm looking
> >> in the wrong place. Or maybe it's the kind of thing on PC hardware that
> >> is just driven by the BIOS without the operating system knowing about it.
> >>
> >> Is there an existing in-kernel driver for such a thing?
> > Why would LEDs connected to a bunch of GPIOs in a specific fashion
> > require a hardware driver?  Doesn't drivers/leds/leds-gpio.c already
> > provide all the support you need?
> Yes I could expose the individual segments as gpio-ledsbut it would be 
> nicer if they worked in a more co-ordinated fashion so I didn't have to 
> care about the individual segments and could just say "display 7" or 
> "display 0".

Still not sure this sort of thing should be kernel-side.

Sounds more like the role of a library or middle-layer.

-- 
Lee Jones [李琼斯]