target/linux/brcm2708/patches-4.14/950-0308-overlays-Add-sdtweak-features-for-network-booting.patch

   1 From eadd32681787b1828ff92ef5046db6568d52ad55 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Tue, 29 May 2018 10:52:11 +0100
   4 Subject: [PATCH 308/454] overlays: Add sdtweak features for network booting
   5
   6 It has been observed that a Pi with no SD card will poll the interface
   7 continuously, using up to 10% CPU. Add some new parameters to the
   8 sdtweak overlay to control this behaviour:
   9
  10 poll_once   Only look for a card once, at boot time. If none is found
  11             then the interface is effectively disabled.
  12
  13 enable      Set to "off" or "no" to completely disable the interface.
  14
  15 See: https://github.com/raspberrypi/linux/issues/2567
  16
  17 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  18 ---
  19  arch/arm/boot/dts/overlays/README              | 10 ++++++++++
  20  arch/arm/boot/dts/overlays/sdtweak-overlay.dts |  2 ++
  21  2 files changed, 12 insertions(+)
  22
  23 --- a/arch/arm/boot/dts/overlays/README
  24 +++ b/arch/arm/boot/dts/overlays/README
  25 @@ -1618,6 +1618,16 @@ Params: overclock_50            Clock (i
  26
  27          debug                   Enable debug output (default off)
  28
  29 +        poll_once               Looks for a card once after booting. Useful
  30 +                                for network booting scenarios to avoid the
  31 +                                overhead of continuous polling. N.B. Using
  32 +                                this option restricts the system to using a
  33 +                                single card per boot (or none at all).
  34 +                                (default off)
  35 +
  36 +        enable                  Set to off to completely disable the interface
  37 +                                (default on)
  38 +
  39
  40  Name:   smi
  41  Info:   Enables the Secondary Memory Interface peripheral. Uses GPIOs 2-25!
  42 --- a/arch/arm/boot/dts/overlays/sdtweak-overlay.dts
  43 +++ b/arch/arm/boot/dts/overlays/sdtweak-overlay.dts
  44 @@ -19,5 +19,7 @@
  45                 force_pio        = <&frag0>,"brcm,force-pio?";
  46                 pio_limit        = <&frag0>,"brcm,pio-limit:0";
  47                 debug            = <&frag0>,"brcm,debug?";
  48 +               enable           = <&frag0>,"status";
  49 +               poll_once        = <&frag0>,"non-removable?";
  50         };
  51  };