Re: [PATCH 06/13] cpuidle: psci: Simplify OF parsing of CPU idle state nodes

From: Sudeep Holla <sudeep.holla@arm.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Lina Iyer <ilina@codeaurora.org>,
	Linux PM <linux-pm@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Kevin Hilman <khilman@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>
Subject: Re: [PATCH 06/13] cpuidle: psci: Simplify OF parsing of CPU idle state nodes
Date: Sun, 27 Oct 2019 02:24:20 +0000	[thread overview]
Message-ID: <20191027022420.GB18111@e107533-lin.cambridge.arm.com> (raw)
In-Reply-To: <CAPDyKFrPqnNENH2bWG=unEWRxLdC0BQEOU9-tYAT175sX7Z7vw@mail.gmail.com>

On Thu, Oct 24, 2019 at 06:33:00PM +0200, Ulf Hansson wrote:
> On Thu, 24 Oct 2019 at 17:36, Sudeep Holla <sudeep.holla@arm.com> wrote:
> >
> > On Thu, Oct 10, 2019 at 01:39:30PM +0200, Ulf Hansson wrote:
> > > Iterating through the idle state nodes in DT, to find out the number of
> > > states that needs to be allocated is unnecessary, as it has already been
> > > done from dt_init_idle_driver(). Therefore, drop the iteration and use the
> > > number we already have at hand.
> > >
> > > Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> > > ---
> > >  drivers/cpuidle/cpuidle-psci.c | 33 ++++++++++++++++-----------------
> > >  1 file changed, 16 insertions(+), 17 deletions(-)
> > >
> > > diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
> > > index 2e91c8d6c211..1195a1056139 100644
> > > --- a/drivers/cpuidle/cpuidle-psci.c
> > > +++ b/drivers/cpuidle/cpuidle-psci.c
> > > @@ -73,28 +73,22 @@ static int __init psci_dt_parse_state_node(struct device_node *np, u32 *state)
> > >       return 0;
> > >  }
> > >
> > > -static int __init psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
> > > +static int __init psci_dt_cpu_init_idle(struct device_node *cpu_node,
> > > +                             unsigned int state_nodes, int cpu)
> >
> > [super nit] Too much in the beginning of the patch to not notice this ;)
> > May need some '(' alignment here and other places in general.
>
> I was trying to find a consistent way of doing it, according to the
> existing code, but I failed. :-)
>
> Two cases exist where calls/functions crosses one line, one use solely
> tabs and the other uses tab+whitespace to align "exactly". You are
> saying that you prefer the latter? If so, I can adopt to that.
>

I am not too picky on these, just found it in the beginning of the patch
and hence mentioned it. If it was in the middle, I am sure I wouldn't have
noticed.

> >
> > >  {
> > > -     int i, ret = 0, count = 0;
> > > +     int i, ret = 0;
> > >       u32 *psci_states;
> > >       struct device_node *state_node;
> > >
> > > -     /* Count idle states */
> > > -     while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
> > > -                                           count))) {
> > > -             count++;
> > > -             of_node_put(state_node);
> > > -     }
> > > -
> > > -     if (!count)
> > > -             return -ENODEV;
> > > -
> > > -     psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
> > > +     psci_states = kcalloc(state_nodes, sizeof(*psci_states), GFP_KERNEL);
> > >       if (!psci_states)
> > >               return -ENOMEM;
> > >
> > > -     for (i = 0; i < count; i++) {
> > > +     for (i = 0; i < state_nodes; i++) {
> > >               state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
> >
> > Can we move above to use of_get_cpu_state_node ? Since it also handles
> > domain-idle-states.
> >
> > > +             if (!state_node)
> > > +                     break;
> > > +
> > >               ret = psci_dt_parse_state_node(state_node, &psci_states[i]);
> > >               of_node_put(state_node);
> > >
> > > @@ -104,6 +98,11 @@ static int __init psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
> > >               pr_debug("psci-power-state %#x index %d\n", psci_states[i], i);
> > >       }
> > >
> > > +     if (i != state_nodes) {
> > > +             ret = -ENODEV;
> > > +             goto free_mem;
> > > +     }
> > > +
> > >       /* Idle states parsed correctly, initialize per-cpu pointer */
> > >       per_cpu(psci_power_state, cpu) = psci_states;
> > >       return 0;
> > > @@ -113,7 +112,7 @@ static int __init psci_dt_cpu_init_idle(struct device_node *cpu_node, int cpu)
> > >       return ret;
> > >  }
> > >
> > > -static __init int psci_cpu_init_idle(unsigned int cpu)
> > > +static __init int psci_cpu_init_idle(unsigned int cpu, unsigned int state_nodes)
> >
> > Does it make sense to rename it as state_count or something similar ?
>
> Let me check to see if it makes sense to change it. Rebasing on top of
> your recently submitted patch, might tell better.
>

Sure.

--
Regards,
Sudeep