linux-kernel - Re: [PATCH] cpuidle: riscv-sbi: Fix CPU_PM_CPU_IDLE_ENTER

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Date:   Fri, 23 Sep 2022 03:55:45 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     anup@...infault.org
CC:     rafael@...nel.org, daniel.lezcano@...aro.org,
        Paul Walmsley <paul.walmsley@...ive.com>,
        ulf.hansson@...aro.org, atishp@...shpatra.org,
        Alistair Francis <Alistair.Francis@....com>,
        linux-pm@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, apatel@...tanamicro.com
Subject:     Re: [PATCH] cpuidle: riscv-sbi: Fix CPU_PM_CPU_IDLE_ENTER_xyz() macro usage

On Thu, 22 Sep 2022 10:07:46 PDT (-0700), Palmer Dabbelt wrote:
> On Sun, 28 Aug 2022 19:59:45 PDT (-0700), anup@...infault.org wrote:
>> Hi Palmer,
>>
>> On Mon, Jul 18, 2022 at 2:16 PM Anup Patel <apatel@...tanamicro.com> wrote:
>>>
>>> Currently, we are using CPU_PM_CPU_IDLE_ENTER_PARAM() for all SBI HSM
>>> suspend types so retentive suspend types are also treated non-retentive
>>> and kernel will do redundant additional work for these states.
>>>
>>> The BIT[31] of SBI HSM suspend types allows us to differentiate between
>>> retentive and non-retentive suspend types so we should use this BIT
>>> to call appropriate CPU_PM_CPU_IDLE_ENTER_xyz() macro.
>>>
>>> Fixes: 6abf32f1d9c5 ("cpuidle: Add RISC-V SBI CPU idle driver")
>>> Signed-off-by: Anup Patel <apatel@...tanamicro.com>
>>
>> Can you please take this patch through the RISC-V tree ?
>
> Sorry I missed this, I didn't realize you wanted me to merge it.  It's
> on fixes.

Actually from reading this again, it's not really a fix: the kernel is 
correct without this change, it's just going to save/restore when it 
doesn't need to.  So I'm queuing this into for-next instead.

>
>>
>> Regards,
>> Anup
>>
>>> ---
>>>  drivers/cpuidle/cpuidle-riscv-sbi.c | 7 ++++++-
>>>  1 file changed, 6 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/cpuidle/cpuidle-riscv-sbi.c b/drivers/cpuidle/cpuidle-riscv-sbi.c
>>> index 1151e5e2ba82..33c92fec4365 100644
>>> --- a/drivers/cpuidle/cpuidle-riscv-sbi.c
>>> +++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
>>> @@ -97,8 +97,13 @@ static int sbi_cpuidle_enter_state(struct cpuidle_device *dev,
>>>                                    struct cpuidle_driver *drv, int idx)
>>>  {
>>>         u32 *states = __this_cpu_read(sbi_cpuidle_data.states);
>>> +       u32 state = states[idx];
>>>
>>> -       return CPU_PM_CPU_IDLE_ENTER_PARAM(sbi_suspend, idx, states[idx]);
>>> +       if (state & SBI_HSM_SUSP_NON_RET_BIT)
>>> +               return CPU_PM_CPU_IDLE_ENTER_PARAM(sbi_suspend, idx, state);
>>> +       else
>>> +               return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(sbi_suspend,
>>> +                                                            idx, state);
>>>  }
>>>
>>>  static int __sbi_enter_domain_idle_state(struct cpuidle_device *dev,
>>> --
>>> 2.34.1
>>>