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From eadd32681787b1828ff92ef5046db6568d52ad55 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Tue, 29 May 2018 10:52:11 +0100
Subject: [PATCH 308/454] overlays: Add sdtweak features for network booting
It has been observed that a Pi with no SD card will poll the interface
continuously, using up to 10% CPU. Add some new parameters to the
sdtweak overlay to control this behaviour:
poll_once Only look for a card once, at boot time. If none is found
then the interface is effectively disabled.
enable Set to "off" or "no" to completely disable the interface.
See: https://github.com/raspberrypi/linux/issues/2567
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
---
arch/arm/boot/dts/overlays/README | 10 ++++++++++
arch/arm/boot/dts/overlays/sdtweak-overlay.dts | 2 ++
2 files changed, 12 insertions(+)
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -1618,6 +1618,16 @@ Params: overclock_50 Clock (i
debug Enable debug output (default off)
+ poll_once Looks for a card once after booting. Useful
+ for network booting scenarios to avoid the
+ overhead of continuous polling. N.B. Using
+ this option restricts the system to using a
+ single card per boot (or none at all).
+ (default off)
+
+ enable Set to off to completely disable the interface
+ (default on)
+
Name: smi
Info: Enables the Secondary Memory Interface peripheral. Uses GPIOs 2-25!
--- a/arch/arm/boot/dts/overlays/sdtweak-overlay.dts
+++ b/arch/arm/boot/dts/overlays/sdtweak-overlay.dts
@@ -19,5 +19,7 @@
force_pio = <&frag0>,"brcm,force-pio?";
pio_limit = <&frag0>,"brcm,pio-limit:0";
debug = <&frag0>,"brcm,debug?";
+ enable = <&frag0>,"status";
+ poll_once = <&frag0>,"non-removable?";
};
};
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