From 980bbff018f64a22af0e75a12ee14cbfbc547e6a Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Wed, 28 Oct 2015 10:39:55 +0100 Subject: [PATCH] ARM64: juno: disable NOR flash node by default After discussing on the mailing list it turns out that accessing the flash memory from the kernel can disrupt CPU sleep states and CPU hotplugging, so let's disable this DT node by default. Setups that want to access the flash can modify this entry to enable the flash again. Quoting Sudeep Holla: "the firmware assumes the flash is always in read mode while Linux leaves NOR flash in "read id" mode after initialization." Reported-by: Sudeep Holla Cc: Mark Rutland Cc: Sudeep Holla Cc: Liviu Dudau Cc: Lorenzo Pieralisi Cc: Catalin Marinas Cc: Leif Lindholm Cc: Ryan Harkin Fixes: 5078f77e1443 "ARM64: juno: add NOR flash to device tree" Signed-off-by: Linus Walleij Signed-off-by: Olof Johansson --- arch/arm64/boot/dts/arm/juno-motherboard.dtsi | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/arm64/boot/dts/arm/juno-motherboard.dtsi b/arch/arm64/boot/dts/arm/juno-motherboard.dtsi index c7c99a42e2e9..8c029ee2a5b5 100644 --- a/arch/arm64/boot/dts/arm/juno-motherboard.dtsi +++ b/arch/arm64/boot/dts/arm/juno-motherboard.dtsi @@ -109,6 +109,13 @@ linux,part-probe = "afs"; reg = <0 0x00000000 0x04000000>; bank-width = <4>; + /* + * Unfortunately, accessing the flash disturbs + * the CPU idle states (suspend) and CPU + * hotplug of the platform. For this reason, + * flash hardware access is disabled by default. + */ + status = "disabled"; }; ethernet@2,00000000 {