31 lines
1.3 KiB
Diff
31 lines
1.3 KiB
Diff
From 81fe79da00f4130ef329d22d6b9433f1ff7f2b6f Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.com>
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Date: Mon, 26 Apr 2021 09:58:14 +0100
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Subject: [PATCH] overlays: README - improve the gpio-poweroff guide
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Signed-off-by: Phil Elwell <phil@raspberrypi.com>
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---
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arch/arm/boot/dts/overlays/README | 11 +++++++++--
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1 file changed, 9 insertions(+), 2 deletions(-)
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--- a/arch/arm/boot/dts/overlays/README
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+++ b/arch/arm/boot/dts/overlays/README
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@@ -987,8 +987,15 @@ Params: <None>
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Name: gpio-poweroff
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-Info: Drives a GPIO high or low on poweroff (including halt). Enabling this
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- overlay will prevent the ability to boot by driving GPIO3 low.
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+Info: Drives a GPIO high or low on poweroff (including halt). Using this
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+ overlay interferes with the normal power-down sequence, preventing the
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+ kernel from resetting the SoC (a necessary step in a normal power-off
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+ or reboot). This also disables the ability to triger a boot by driving
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+ GPIO3 low.
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+
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+ Users of this overlay are required to provide an external mechanism to
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+ switch off the power supply when signalled - failure to do so results
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+ in a kernel BUG, increased power consumption and undefined behaviour.
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Load: dtoverlay=gpio-poweroff,<param>=<val>
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Params: gpiopin GPIO for signalling (default 26)
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