Re: [PATCH 1/5] cpuidle: psci: Fail cpuidle registration if set OSI mode failed

From: Lina Iyer <ilina@codeaurora.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>,
	Saravana Kannan <saravanak@google.com>,
	linux-pm@vger.kernel.org,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Stephen Boyd <sboyd@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Benjamin Gaignard <benjamin.gaignard@st.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/5] cpuidle: psci: Fail cpuidle registration if set OSI mode failed
Date: Thu, 18 Jun 2020 12:01:50 -0600	[thread overview]
Message-ID: <20200618180150.GK12942@codeaurora.org> (raw)
In-Reply-To: <20200615152054.6819-2-ulf.hansson@linaro.org>

On Mon, Jun 15 2020 at 09:21 -0600, Ulf Hansson wrote:
>Currently we allow the cpuidle driver registration to succeed, even if we
>failed to enable the OSI mode when the hierarchical DT layout is used. This
>means running in a degraded mode, by using the available idle states per
>CPU, while also preventing the domain idle states.
>
>Moving forward, this behaviour looks quite questionable to maintain, as
>complexity seems to grow around it, especially when trying to add support
>for deferred probe, for example.
>
>Therefore, let's make the cpuidle driver registration to fail in this
>situation, thus relying on the default architectural cpuidle backend for
>WFI to be used.
>
>Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

May be PATCH 3/5 should come before this change, but for this patch itself,
please consider -

Reviewed-by: Lina Iyer <ilina@codeaurora.org>

>---
> drivers/cpuidle/cpuidle-psci-domain.c | 5 -----
> 1 file changed, 5 deletions(-)
>
>diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
>index 423f03bbeb74..f07786aad673 100644
>--- a/drivers/cpuidle/cpuidle-psci-domain.c
>+++ b/drivers/cpuidle/cpuidle-psci-domain.c
>@@ -26,7 +26,6 @@ struct psci_pd_provider {
> };
>
> static LIST_HEAD(psci_pd_providers);
>-static bool osi_mode_enabled __initdata;
>
> static int psci_pd_power_off(struct generic_pm_domain *pd)
> {
>@@ -272,7 +271,6 @@ static int __init psci_idle_init_domains(void)
> 		goto remove_pd;
> 	}
>
>-	osi_mode_enabled = true;
> 	of_node_put(np);
> 	pr_info("Initialized CPU PM domain topology\n");
> 	return pd_count;
>@@ -293,9 +291,6 @@ struct device __init *psci_dt_attach_cpu(int cpu)
> {
> 	struct device *dev;
>
>-	if (!osi_mode_enabled)
>-		return NULL;
>-
> 	dev = dev_pm_domain_attach_by_name(get_cpu_device(cpu), "psci");
> 	if (IS_ERR_OR_NULL(dev))
> 		return dev;
>-- 
>2.20.1
>