linux-kernel - Re: [PATCH v16 4/6] soc: qcom: rpmh: Invoke rpmh

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Date:   Wed, 8 Apr 2020 12:38:48 +0530
From:   Maulik Shah <mkshah@...eaurora.org>
To:     Stephen Boyd <swboyd@...omium.org>, bjorn.andersson@...aro.org,
        dianders@...omium.org, evgreen@...omium.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        agross@...nel.org, mka@...omium.org, rnayak@...eaurora.org,
        ilina@...eaurora.org, lsrao@...eaurora.org
Subject: Re: [PATCH v16 4/6] soc: qcom: rpmh: Invoke rpmh_flush() for dirty
 caches

Hi,

On 4/8/2020 8:20 AM, Stephen Boyd wrote:
> Quoting Maulik Shah (2020-04-05 23:32:19)
>> Add changes to invoke rpmh flush() from CPU PM notification.
>> This is done when the last the cpu is entering power collapse and
>> controller is not busy.
>>
>> Controllers that do have 'HW solver' mode do not need to register
> Controllers that have 'HW solver' mode don't need to register? The 'do
> have' is throwing me off.
Okay i will remove 'do' from this line.
>> for CPU PM notification. They may be in autonomous mode executing
>> low power mode and do not require rpmh_flush() to happen from CPU
>> PM notification.
>>
>> Signed-off-by: Maulik Shah <mkshah@...eaurora.org>
>> Reviewed-by: Douglas Anderson <dianders@...omium.org>
>> ---
>>   drivers/soc/qcom/rpmh-internal.h |  25 +++++---
>>   drivers/soc/qcom/rpmh-rsc.c      | 123 +++++++++++++++++++++++++++++++++++----
>>   drivers/soc/qcom/rpmh.c          |  26 +++------
>>   3 files changed, 137 insertions(+), 37 deletions(-)
>>
>> diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
>> index b718221..fbe1f3e 100644
>> --- a/drivers/soc/qcom/rpmh-rsc.c
>> +++ b/drivers/soc/qcom/rpmh-rsc.c
>> @@ -6,6 +6,7 @@
> [...]
>> +
>> +static int rpmh_rsc_cpu_pm_callback(struct notifier_block *nfb,
>> +                                   unsigned long action, void *v)
>> +{
>> +       struct rsc_drv *drv = container_of(nfb, struct rsc_drv, rsc_pm);
>> +       int ret = NOTIFY_OK;
>> +
>> +       spin_lock(&drv->pm_lock);
>> +
>> +       switch (action) {
>> +       case CPU_PM_ENTER:
> I thought CPU_PM notifiers weren't supposed to be used anymore? Or at
> least, the genpd work that has gone on for cpuidle could be used here in
> place of CPU_PM notifiers?

genpd was used in v3 and v4 of this series, where from pd's .power_off  
function, rpmh_flush() was invoked.

genpd can be useful if target firmware supports PSCI's OSI mode, while 
sc7180 is non-OSI target.

The current approch (using cpu pm notification) can be used for both OSI 
and non-OSI targets to invoke rpmh_flush() when last cpu goes to power down.

> And so this isn't actually any different
> than what was proposed originally to use genpd for this?
>
>> +               cpumask_set_cpu(raw_smp_processor_id(),
> Why do we need to use raw_smp_processor_id()? smp_processor_id() should
> work just as well?
Yes, seems it will work as well. I will change to use smp_processor_id().
>
>> +                               &drv->cpus_entered_pm);
>> +
>> +               if (!cpumask_equal(&drv->cpus_entered_pm, cpu_online_mask))
>> +                       goto exit;
>> +               break;
>> +       case CPU_PM_ENTER_FAILED:
>> +       case CPU_PM_EXIT:
>> +               cpumask_clear_cpu(raw_smp_processor_id(),
>> +                                 &drv->cpus_entered_pm);
>> +               goto exit;
>> +       }
>> +
>> +       ret = rpmh_rsc_ctrlr_is_busy(drv);
>> +       if (ret) {
>> +               ret = NOTIFY_BAD;
>> +               goto exit;
>> +       }
>> +
>> +       ret = rpmh_flush(&drv->client);
>> +       if (ret)
>> +               ret = NOTIFY_BAD;
>> +       else
>> +               ret = NOTIFY_OK;
>> +
>> +exit:
>> +       spin_unlock(&drv->pm_lock);
>> +       return ret;
>> +}
>> +
Thanks,
Maulik

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