From: neilneil2000 <31366098+neilneil2000@users.noreply.github.com>
Date: Thu, 12 Oct 2017 16:29:43 +0000 (+0100)
Subject: GPIO and gpio-poweroff clarifications
X-Git-Tag: archive/raspbian/4.9.82-1+deb9u3+rpi1_jessie~5^2~80
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=cd36c6ce8499a0409184aedbc5276cb62810ffc9;p=linux-4.9.git

GPIO and gpio-poweroff clarifications

Notes added:
1) All GPIO references use the hardware numbering scheme
2) Enabling gpio-poweroff prevents the ability to boot the pi by driving GPIO3 low
---

diff --git a/arch/arm/boot/dts/overlays/README b/arch/arm/boot/dts/overlays/README
index d4eeeae10671..011b2c696df7 100644
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -33,6 +33,9 @@ needed.
 Configuring additional, optional hardware is done using Device Tree overlays
 (see below).
 
+GPIO numbering uses the hardware pin numbering scheme (aka BCM scheme) and 
+not the physical pin numbers.
+
 raspi-config
 ============
 
@@ -496,7 +499,8 @@ Params: gpio_pin                Input pin number. Default is 18.
 
 
 Name:   gpio-poweroff
-Info:   Drives a GPIO high or low on poweroff (including halt)
+Info:   Drives a GPIO high or low on poweroff (including halt). Enabling this
+        overlay will prevent the ability to boot by driving GPIO3 low.
 Load:   dtoverlay=gpio-poweroff,<param>=<val>
 Params: gpiopin                 GPIO for signalling (default 26)