linux-kernel - [RFC v5 2/3] cpuidle : Add callback whenever a state usage is enabled/disabled

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Date:   Thu,  3 Oct 2019 01:26:45 -0500
From:   Abhishek Goel <huntbag@...ux.vnet.ibm.com>
To:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Cc:     npiggin@...il.com, rjw@...ysocki.net, daniel.lezcano@...aro.org,
        mpe@...erman.id.au, ego@...ux.vnet.ibm.com, dja@...ens.net,
        Abhishek Goel <huntbag@...ux.vnet.ibm.com>
Subject: [RFC v5 2/3] cpuidle : Add callback whenever a state usage is enabled/disabled

To force wakeup a cpu, we need to compute the timeout in the fast idle
path as a state may be enabled or disabled but there did not exist a
feedback to driver when a state is enabled or disabled.
This patch adds a callback whenever a state_usage records a store for
disable attribute

Signed-off-by: Abhishek Goel <huntbag@...ux.vnet.ibm.com>
---
 drivers/cpuidle/sysfs.c | 15 ++++++++++++++-
 include/linux/cpuidle.h |  3 +++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
index 2bb2683b4..6c9bf2f7b 100644
--- a/drivers/cpuidle/sysfs.c
+++ b/drivers/cpuidle/sysfs.c
@@ -418,8 +418,21 @@ static ssize_t cpuidle_state_store(struct kobject *kobj, struct attribute *attr,
 	struct cpuidle_state_attr *cattr = attr_to_stateattr(attr);
 	struct cpuidle_device *dev = kobj_to_device(kobj);
 
-	if (cattr->store)
+	if (cattr->store) {
 		ret = cattr->store(state, state_usage, buf, size);
+		if (ret == size &&
+			strncmp(cattr->attr.name, "disable",
+						strlen("disable"))) {
+			struct kobject *cpuidle_kobj = kobj->parent;
+			struct cpuidle_device *dev =
+					to_cpuidle_device(cpuidle_kobj);
+			struct cpuidle_driver *drv =
+					cpuidle_get_cpu_driver(dev);
+
+			if (drv->disable_callback)
+				drv->disable_callback(dev, drv);
+		}
+	}
 
 	/* reset poll time cache */
 	dev->poll_limit_ns = 0;
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 4b6b5bea8..1729a497b 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -122,6 +122,9 @@ struct cpuidle_driver {
 	/* the driver handles the cpus in cpumask */
 	struct cpumask		*cpumask;
 
+	void (*disable_callback)(struct cpuidle_device *dev,
+				 struct cpuidle_driver *drv);
+
 	/* preferred governor to switch at register time */
 	const char		*governor;
 };
-- 
2.17.1