On Tue, 4 Dec 2018 at 19:45, Lina Iyer [off-list ref] wrote:

On Thu, Nov 29 2018 at 10:50 -0700, Ulf Hansson wrote:

quoted

Introduce a new PSCI DT helper function, psci_dt_attach_cpu(), which takes
a CPU number as an in-parameter and attaches the CPU's struct device to its
corresponding PM domain. Additionally, the helper prepares the CPU to be
power managed via runtime PM, which is the last step needed to enable the
interaction with the PM domain through the runtime PM callbacks.

Signed-off-by: Ulf Hansson <redacted>
---

Changes in v10:
      - New patch: Replaces "PM / Domains: Add helper functions to
        attach/detach CPUs to/from genpd".

---
drivers/firmware/psci/psci.h           |  1 +
drivers/firmware/psci/psci_pm_domain.c | 19 +++++++++++++++++++
2 files changed, 20 insertions(+)

diff --git a/drivers/firmware/psci/psci.h b/drivers/firmware/psci/psci.h
index 05af462cc96e..fbc9980dee69 100644
--- a/drivers/firmware/psci/psci.h
+++ b/drivers/firmware/psci/psci.h

@@ -15,6 +15,7 @@ int psci_dt_parse_state_node(struct device_node *np, u32 *state);

int psci_dt_init_pm_domains(struct device_node *np);
int psci_dt_pm_domains_parse_states(struct cpuidle_driver *drv,
                      struct device_node *cpu_node, u32 *psci_states);
+int psci_dt_attach_cpu(int cpu);
#else
static inline int psci_dt_init_pm_domains(struct device_node *np) { return 0; }
#endif

diff --git a/drivers/firmware/psci/psci_pm_domain.c b/drivers/firmware/psci/psci_pm_domain.c
index 6c9d6a644c7f..b0fa7da8a0ce 100644
--- a/drivers/firmware/psci/psci_pm_domain.c
+++ b/drivers/firmware/psci/psci_pm_domain.c

@@ -12,8 +12,10 @@

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/string.h>
+#include <linux/cpu.h>
#include <linux/cpuidle.h>
#include <linux/cpu_pm.h>

@@ -367,4 +369,21 @@ int psci_dt_pm_domains_parse_states(struct cpuidle_driver *drv,

      return 0;

}
+
+int psci_dt_attach_cpu(int cpu)
+{
+      struct device *dev = get_cpu_device(cpu);
+      int ret;
+
+      ret = dev_pm_domain_attach(dev, true);
+      if (ret)
+              return ret;
+
+      pm_runtime_irq_safe(dev);
+      pm_runtime_get_noresume(dev);
+      pm_runtime_set_active(dev);

You would want to set this only if the CPU is online. Otherwise we will
not power down the domain, if the CPU was never brought online.

Nice catch!

The platforms I tested this series on brings all their CPUs online
during boot, hence I haven't observed the problem.

I will post a new version soon to address the problem. Again, thanks
for your review!

[...]

Kind regards
Uffe

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