[1/2] ARM: vexpress: Set-up shared OPP table instead of individual for each CPU

Message ID 20191128101547.519-1-sudeep.holla@arm.com
State Accepted
Commit 2a76352ad2cc6b78e58f737714879cc860903802
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Series
  • [1/2] ARM: vexpress: Set-up shared OPP table instead of individual for each CPU
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Commit Message

Sudeep Holla Nov. 28, 2019, 10:15 a.m.
Currently we add individual copy of same OPP table for each CPU within
the cluster. This is redundant and doesn't reflect the reality.

We can't use core cpumask to set policy->cpus in ve_spc_cpufreq_init()
anymore as it gets called via cpuhp_cpufreq_online()->cpufreq_online()
->cpufreq_driver->init() and the cpumask gets updated upon CPU hotplug
operations. It also may cause issues when the vexpress_spc_cpufreq
driver is built as a module.

Since ve_spc_clk_init is built-in device initcall, we should be able to
use the same topology_core_cpumask to set the opp sharing cpumask via
dev_pm_opp_set_sharing_cpus and use the same later in the driver via
dev_pm_opp_get_sharing_cpus.

Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

---
 arch/arm/mach-vexpress/spc.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

-- 
2.17.1

Comments

Sudeep Holla Nov. 29, 2019, 11:49 a.m. | #1
Hi Viresh, Rafael,

On Thu, Nov 28, 2019 at 10:15:47AM +0000, Sudeep Holla wrote:
> Since commit ca74b316df96 ("arm: Use common cpu_topology structure and

> functions.") the core cpumask has to be modified during cpu hotplug

> operations. So using them to set up cpufreq policy cpumask may be

> incorrect as it may contain only cpus that are online at that instance.

>

> Instead, we can use the cpumask setup by OPP library that contains all

> the cpus sharing OPP table using dev_pm_opp_get_sharing_cpus.

>

> Cc: Viresh Kumar <viresh.kumar@linaro.org>


This can go independently via PM tree and I can take 1/2 via SoC tree
(as the file is being moved). The problem will be fixed only after both
lands, but this alone won't break the build. Or if you guys provide
Ack, I can take both together via ARM SoC team. Let me know.

--
Regards,
Sudeep
Sudeep Holla Dec. 2, 2019, 11:11 a.m. | #2
On Mon, Dec 02, 2019 at 07:31:46AM +0530, Viresh Kumar wrote:
> On 29-11-19, 11:49, Sudeep Holla wrote:

> > Hi Viresh, Rafael,

> >

> > On Thu, Nov 28, 2019 at 10:15:47AM +0000, Sudeep Holla wrote:

> > > Since commit ca74b316df96 ("arm: Use common cpu_topology structure and

> > > functions.") the core cpumask has to be modified during cpu hotplug

> > > operations. So using them to set up cpufreq policy cpumask may be

> > > incorrect as it may contain only cpus that are online at that instance.

> > >

> > > Instead, we can use the cpumask setup by OPP library that contains all

> > > the cpus sharing OPP table using dev_pm_opp_get_sharing_cpus.

> > >

> > > Cc: Viresh Kumar <viresh.kumar@linaro.org>

> >

> > This can go independently via PM tree and I can take 1/2 via SoC tree

> > (as the file is being moved). The problem will be fixed only after both

> > lands, but this alone won't break the build.

>

> Yes, but it will break cpufreq for sure as shared-cpus won't be set by anyone.

>


It's already broke on hotplug :) but yes works on boot at-least.

> > Or if you guys provide

> > Ack, I can take both together via ARM SoC team. Let me know.

>

> I was planning to take them through cpufreq tree, but that fine if you can do

> that.

>


Arnd moved and compressed few folders in arch/arm/mach-*, and vexpress
was merged into versatile. Not sure if it's planned for v5.5, so to be
cautious, I preferred to take it via ARM SoC.

> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>


Thanks, I will take them together via ARM SoC

--
Regards,
Sudeep

Patch

diff --git a/arch/arm/mach-vexpress/spc.c b/arch/arm/mach-vexpress/spc.c
index 354e0e7025ae..1da11bdb1dfb 100644
--- a/arch/arm/mach-vexpress/spc.c
+++ b/arch/arm/mach-vexpress/spc.c
@@ -551,8 +551,9 @@  static struct clk *ve_spc_clk_register(struct device *cpu_dev)
 
 static int __init ve_spc_clk_init(void)
 {
-	int cpu;
+	int cpu, cluster;
 	struct clk *clk;
+	bool init_opp_table[MAX_CLUSTERS] = { false };
 
 	if (!info)
 		return 0; /* Continue only if SPC is initialised */
@@ -578,8 +579,17 @@  static int __init ve_spc_clk_init(void)
 			continue;
 		}
 
+		cluster = topology_physical_package_id(cpu_dev->id);
+		if (init_opp_table[cluster])
+			continue;
+
 		if (ve_init_opp_table(cpu_dev))
 			pr_warn("failed to initialise cpu%d opp table\n", cpu);
+		else if (dev_pm_opp_set_sharing_cpus(cpu_dev,
+			 topology_core_cpumask(cpu_dev->id)))
+			pr_warn("failed to mark OPPs shared for cpu%d\n", cpu);
+		else
+			init_opp_table[cluster] = true;
 	}
 
 	platform_device_register_simple("vexpress-spc-cpufreq", -1, NULL, 0);