linux-kernel - Re: [PATCH 2/3] platform/x86/pcengines-apuv2: add legacy leds gpio definitions

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Date:   Wed, 10 Jul 2019 15:07:12 +0200
From:   "Enrico Weigelt, metux IT consult" <lkml@...ux.net>
To:     Florian Eckert <fe@....tdt.de>
Cc:     Eckert.Florian@...glemail.com, info@...ux.net,
        dvhart@...radead.org, andy@...radead.org,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] platform/x86/pcengines-apuv2: add legacy leds gpio
 definitions

On 10.07.19 14:03, Florian Eckert wrote:

> I have back ported your pcengines-apuv2 device and gpio-amd-fch GPIO
> driver to the kernel version 4.19 on OpenWrt.
> If I compile and load this without the change no LEDs are visible in
> "/sys/class/leds"!

Maybe this old kernel just ignored all entries w/o gpio ID. Note that
these IDs are deprecated for quite a while and shouldn't be used in new
code anymore.

> From my point of view the connection between the GPIO and the LEDs
> subsystem is missing.
> How should the LED subsystem know which GPIO to use?

See gpiod_lookup_table.

> If I add the change to the pcengines-apuv2 device then the LEDs will be
> visilbe under "/sys/class/leds"
> and could be used, by OpenWrt userland.
> 
> Mybe I miss something.

Your patch is only valid for your backport onto this old kernel, not for
recent mainline.


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@...ux.net -- +49-151-27565287