linux-kernel - Re: [PATCH v5] cpuidle: sunplus: Create cpuidle driver for sunplus sp7021

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Message-ID: <a2871e71-02af-198f-3944-d6565f3cd5f9@arm.com>
Date:   Tue, 1 Mar 2022 12:23:54 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Edwin Chiu 邱垂峰 <edwin.chiu@...plus.com>
Cc:     Edwin Chiu <edwinchiu0505tw@...il.com>,
        Sudeep Holla <sudeep.holla@....com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "rafael@...nel.org" <rafael@...nel.org>,
        "daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v5] cpuidle: sunplus: Create cpuidle driver for sunplus
 sp7021

On Tue, Mar 01, 2022 at 09:18:31AM +0000, Edwin Chiu 邱垂峰 wrote:
> > 
> > You really don't need a cpuidle driver to just WFI for any states.
> > Add the driver when you have something non WFI in the suspend function.
> >

This is still valid and you haven't responded to this.

> > > +static const struct of_device_id sp7021_idle_state_match[] = {
> > > +	{ .compatible = "arm,idle-state", .data = sp7021_cpu_spc },
> > > +	{ },
> > > +};
> > 
> > This is better than adding new driver like you did in previous version.
> > 
> > I did a quick check but couldn't figure out. How do cpus get switched ON
> > or OFF on this platform(for example during CPU hotplug) ?.
> > 
> 
> In this patch, I just want to submit cpuidle function.
> So there have no cpu hotplug function now.


You need to document the binding now for both idle and hotplug. You
can't mix and match. You can either use PSCI or custom "sunplus,sc-smp"
for both cpu on/off and suspend. So you must document it now even if you
don't plan to support hotplug now. And when you add later, you must use
the same method.

However, you still don't need this driver for just WFI, so please
explain why you think otherwise. Until then, you still won't get ACK
from my side.

-- 
Regards,
Sudeep