From 6f3710f1f65fdc0da2b042ea6a9a738ddd146d4e Mon Sep 17 00:00:00 2001 From: Sudeep Holla Date: Wed, 29 May 2019 14:29:45 +0100 Subject: [PATCH] arm: dts: vexpress-v2p-ca15_a7: disable NOR flash node by default Accessing the NOR flash memory from the kernel will disrupt CPU sleep/ idles states and CPU hotplugging. We need to disable this DT node by default. Setups that want to access the flash can modify this entry to enable the flash again but also ensuring to disable CPU idle states and CPU hotplug. The platform firmware assumes the flash is always in read mode while Linux kernel driver leaves NOR flash in "read id" mode after initialization. If it gets used actively, it can be in some other state. So far we had not seen this issue as the NOR flash drivers in kernel were not enabled by default. However it was enable in multi_v7 config by Commit 5f068190cc10 ("ARM: multi_v7_defconfig: Enable support for CFI NOR FLASH") So, let's mark the NOR flash disabled so that the platform can boot again. This based on: Commit 980bbff018f6 ("ARM64: juno: disable NOR flash node by default") Cc: Liviu Dudau Cc: Lorenzo Pieralisi Reviewed-by: Linus Walleij Signed-off-by: Sudeep Holla --- arch/arm/boot/dts/vexpress-v2m-rs1.dtsi | 2 +- arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts | 9 +++++++++ 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/arm/boot/dts/vexpress-v2m-rs1.dtsi b/arch/arm/boot/dts/vexpress-v2m-rs1.dtsi index d3963e9eaf48..1b5bc536c547 100644 --- a/arch/arm/boot/dts/vexpress-v2m-rs1.dtsi +++ b/arch/arm/boot/dts/vexpress-v2m-rs1.dtsi @@ -30,7 +30,7 @@ #interrupt-cells = <1>; ranges; - flash@0,00000000 { + nor_flash: flash@0,00000000 { compatible = "arm,vexpress-flash", "cfi-flash"; reg = <0 0x00000000 0x04000000>, <4 0x00000000 0x04000000>; diff --git a/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts b/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts index 164c904c9992..1de0a658adf1 100644 --- a/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts +++ b/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts @@ -680,3 +680,12 @@ <0 3 &gic 0 39 4>; }; }; + +&nor_flash { + /* + * Unfortunately, accessing the flash disturbs the CPU idle states + * (suspend) and CPU hotplug of this platform. For this reason, flash + * hardware access is disabled by default on this platform alone. + */ + status = "disabled"; +};