Re: [PATCH v10 02/27] PM / Domains: Add support for CPU devices to genpd

On Wed, 19 Dec 2018 at 10:53, Daniel Lezcano [off-list ref] wrote:

On 29/11/2018 18:46, Ulf Hansson wrote:

quoted

To enable a device belonging to a CPU to be attached to a PM domain managed
by genpd, let's do a few changes to it, as to make it convenient to manage
the specifics around CPUs.

To be able to quickly find out what CPUs that are attached to a genpd,
which typically becomes useful from a genpd governor as following changes
is about to show, let's add a cpumask to the struct generic_pm_domain. At
the point when a CPU device gets attached to a genpd, let's update its
cpumask. Moreover, let's also propagate changes to the cpumask upwards in
the topology to the master PM domains. In this way, the cpumask for a genpd
hierarchically reflects all CPUs attached to the topology below it.

Finally, let's make this an opt-in feature, to avoid having to manage CPUs
and the cpumask for a genpd that doesn't need it. For that reason, let's
add a new genpd configuration bit, GENPD_FLAG_CPU_DOMAIN.

Cc: Lina Iyer <redacted>
Co-developed-by: Lina Iyer <redacted>
Signed-off-by: Ulf Hansson <redacted>
---

Changes in v10:
      - Don't allocate the cpumask when not used.
      - Simplify the code that updates the cpumask.
      - Document the GENPD_FLAG_CPU_DOMAIN.

---
 drivers/base/power/domain.c | 66 ++++++++++++++++++++++++++++++++++++-
 include/linux/pm_domain.h   | 13 ++++++++
 2 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index e27b91d36a2a..c3ff8e395308 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c

@@ -20,6 +20,7 @@
 #include <linux/sched.h>
 #include <linux/suspend.h>
 #include <linux/export.h>
+#include <linux/cpu.h>

 #include "power.h"

@@ -126,6 +127,7 @@ static const struct genpd_lock_ops genpd_spin_ops = {
 #define genpd_is_irq_safe(genpd)     (genpd->flags & GENPD_FLAG_IRQ_SAFE)
 #define genpd_is_always_on(genpd)    (genpd->flags & GENPD_FLAG_ALWAYS_ON)
 #define genpd_is_active_wakeup(genpd)        (genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
+#define genpd_is_cpu_domain(genpd)   (genpd->flags & GENPD_FLAG_CPU_DOMAIN)

 static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
              const struct generic_pm_domain *genpd)

@@ -1377,6 +1379,56 @@ static void genpd_free_dev_data(struct device *dev,
      dev_pm_put_subsys_data(dev);
 }

+static void __genpd_update_cpumask(struct generic_pm_domain *genpd,
+                                int cpu, bool set, unsigned int depth)
+{
+     struct gpd_link *link;
+
+     if (!genpd_is_cpu_domain(genpd))
+             return;

With this test, we won't continue updating the cpumask for the other
masters. Is it done on purpose ?

Correct, and yes it's on purpose.

We are not even allocating the cpumask for the genpd in question,
unless it has the GENPD_FLAG_CPU_DOMAIN set.

[...]

Kind regards
Uffe

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel