From eadd32681787b1828ff92ef5046db6568d52ad55 Mon Sep 17 00:00:00 2001 From: Phil Elwell 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 --- 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?"; }; };