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