linux-kernel - Re: [PATCH v8 1/8] RISC-V: Enable CPU

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Date:   Tue, 12 Oct 2021 00:04:31 +0200
From:   Heiko Stübner <heiko@...ech.de>
To:     Palmer Dabbelt <palmer@...belt.com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Pavel Machek <pavel@....cz>, Rob Herring <robh+dt@...nel.org>,
        linux-riscv@...ts.infradead.org
Cc:     Sandeep Tripathy <milun.tripathy@...il.com>,
        Atish Patra <atish.patra@....com>,
        Alistair Francis <Alistair.Francis@....com>,
        Liush <liush@...winnertech.com>,
        Anup Patel <anup@...infault.org>, devicetree@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Anup Patel <anup.patel@....com>,
        Anup Patel <anup.patel@....com>
Subject: Re: [PATCH v8 1/8] RISC-V: Enable CPU_IDLE drivers

Hi Anup,

Am Montag, 11. Oktober 2021, 10:18:13 CEST schrieb Anup Patel:
> We force select CPU_PM and provide asm/cpuidle.h so that we can
> use CPU IDLE drivers for Linux RISC-V kernel.
> 
> Signed-off-by: Anup Patel <anup.patel@....com>
> ---
>  arch/riscv/Kconfig                |  7 +++++++
>  arch/riscv/configs/defconfig      |  1 +
>  arch/riscv/configs/rv32_defconfig |  1 +
>  arch/riscv/include/asm/cpuidle.h  | 24 ++++++++++++++++++++++++
>  arch/riscv/kernel/process.c       |  3 ++-
>  5 files changed, 35 insertions(+), 1 deletion(-)
>  create mode 100644 arch/riscv/include/asm/cpuidle.h
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 8de2afb460f7..d02f1f5a2431 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -46,6 +46,7 @@ config RISCV
>  	select CLONE_BACKWARDS
>  	select CLINT_TIMER if !MMU
>  	select COMMON_CLK
> +	select CPU_PM if CPU_IDLE
>  	select EDAC_SUPPORT
>  	select GENERIC_ARCH_TOPOLOGY if SMP
>  	select GENERIC_ATOMIC64 if !64BIT
> @@ -564,5 +565,11 @@ source "kernel/power/Kconfig"
>  
>  endmenu
>  
> +menu "CPU Power Management"
> +
> +source "drivers/cpuidle/Kconfig"
> +
> +endmenu
> +
>  source "arch/riscv/kvm/Kconfig"
>  source "drivers/firmware/Kconfig"
> diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
> index be21f54e9b91..39b4c32e7997 100644
> --- a/arch/riscv/configs/defconfig
> +++ b/arch/riscv/configs/defconfig
> @@ -20,6 +20,7 @@ CONFIG_SOC_SIFIVE=y
>  CONFIG_SOC_VIRT=y
>  CONFIG_SMP=y
>  CONFIG_HOTPLUG_CPU=y
> +CONFIG_CPU_IDLE=y
>  CONFIG_VIRTUALIZATION=y
>  CONFIG_KVM=y
>  CONFIG_JUMP_LABEL=y

This doesn't apply.

In the history of your tree that you referenced in the cover-letter
I found "RISC-V: Enable KVM for RV64 and RV32"
with that nice "DO NOT UPSTREAM !!!!!" message in caps in it ;-)

This of course makes this not apply on the main riscv tree.

So you might want to base your series on top of a clean "for-next"
branch of Palmer's tree instead of collecting other stuff below it.

Same for rv32_defconfig below.


Heiko


> diff --git a/arch/riscv/configs/rv32_defconfig b/arch/riscv/configs/rv32_defconfig
> index ad01f50c98f1..fed827c82a9e 100644
> --- a/arch/riscv/configs/rv32_defconfig
> +++ b/arch/riscv/configs/rv32_defconfig
> @@ -20,6 +20,7 @@ CONFIG_SOC_VIRT=y
>  CONFIG_ARCH_RV32I=y
>  CONFIG_SMP=y
>  CONFIG_HOTPLUG_CPU=y
> +CONFIG_CPU_IDLE=y
>  CONFIG_VIRTUALIZATION=y
>  CONFIG_KVM=y
>  CONFIG_JUMP_LABEL=y
> diff --git a/arch/riscv/include/asm/cpuidle.h b/arch/riscv/include/asm/cpuidle.h
> new file mode 100644
> index 000000000000..71fdc607d4bc
> --- /dev/null
> +++ b/arch/riscv/include/asm/cpuidle.h
> @@ -0,0 +1,24 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (C) 2021 Allwinner Ltd
> + * Copyright (C) 2021 Western Digital Corporation or its affiliates.
> + */
> +
> +#ifndef _ASM_RISCV_CPUIDLE_H
> +#define _ASM_RISCV_CPUIDLE_H
> +
> +#include <asm/barrier.h>
> +#include <asm/processor.h>
> +
> +static inline void cpu_do_idle(void)
> +{
> +	/*
> +	 * Add mb() here to ensure that all
> +	 * IO/MEM accesses are completed prior
> +	 * to entering WFI.
> +	 */
> +	mb();
> +	wait_for_interrupt();
> +}
> +
> +#endif
> diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
> index 03ac3aa611f5..504b496787aa 100644
> --- a/arch/riscv/kernel/process.c
> +++ b/arch/riscv/kernel/process.c
> @@ -23,6 +23,7 @@
>  #include <asm/string.h>
>  #include <asm/switch_to.h>
>  #include <asm/thread_info.h>
> +#include <asm/cpuidle.h>
>  
>  register unsigned long gp_in_global __asm__("gp");
>  
> @@ -37,7 +38,7 @@ extern asmlinkage void ret_from_kernel_thread(void);
>  
>  void arch_cpu_idle(void)
>  {
> -	wait_for_interrupt();
> +	cpu_do_idle();
>  	raw_local_irq_enable();
>  }
>  
>