Re: [PATCH v8 1/8] RISC-V: Enable CPU_IDLE drivers

[Anup Patel <anup@brainfault.org>]

On Tue, Oct 12, 2021 at 3:34 AM Heiko Stübner <heiko@sntech.de> wrote:
>
> 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@wdc.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.

I usually base everything on the most recent Linus release tag.

This time I accidentally rebased on my KVM RISC-V branch which
was merged recently.

I will anyway send v9.

Regards,
Anup

>
> 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();
> >  }
> >
> >
>
>
>
>