linux-kernel - [PATCH 1/2] ACPI / EC: Add PM operations to tune polling mode efficiency

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Date:	Thu, 21 Jul 2016 17:36:06 +0800
From:	Lv Zheng <lv.zheng@...el.com>
To:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>
Cc:	Lv Zheng <lv.zheng@...el.com>, Lv Zheng <zetalog@...il.com>,
	<linux-kernel@...r.kernel.org>, linux-acpi@...r.kernel.org
Subject: [PATCH 1/2] ACPI / EC: Add PM operations to tune polling mode efficiency

When the PM code disables all IRQs, EC will be in polling mode, it is
efficient to use busy polling with zero timeout in such cases.

Signed-off-by: Lv Zheng <lv.zheng@...el.com>
---
 drivers/acpi/ec.c       |   53 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/acpi/internal.h |    2 ++
 2 files changed, 55 insertions(+)

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
index 999a109..c2d135d 100644
--- a/drivers/acpi/ec.c
+++ b/drivers/acpi/ec.c
@@ -1613,6 +1613,58 @@ error:
 	return ret;
 }
 
+#ifdef CONFIG_PM_SLEEP
+static void acpi_ec_enter_noirq(struct acpi_ec *ec)
+{
+	unsigned long flags;
+
+	if (ec == first_ec) {
+		spin_lock_irqsave(&ec->lock, flags);
+		ec->saved_busy_polling = ec_busy_polling;
+		ec->saved_polling_guard = ec_polling_guard;
+		ec_busy_polling = true;
+		ec_polling_guard = 0;
+		ec_log_drv("interrupt blocked");
+		spin_unlock_irqrestore(&ec->lock, flags);
+	}
+}
+
+static void acpi_ec_leave_noirq(struct acpi_ec *ec)
+{
+	unsigned long flags;
+
+	if (ec == first_ec) {
+		spin_lock_irqsave(&ec->lock, flags);
+		ec_busy_polling = ec->saved_busy_polling;
+		ec_polling_guard = ec->saved_polling_guard;
+		ec_log_drv("interrupt unblocked");
+		spin_unlock_irqrestore(&ec->lock, flags);
+	}
+}
+
+static int acpi_ec_suspend_noirq(struct device *dev)
+{
+	struct acpi_ec *ec =
+		acpi_driver_data(to_acpi_device(dev));
+
+	acpi_ec_enter_noirq(ec);
+	return 0;
+}
+
+static int acpi_ec_resume_noirq(struct device *dev)
+{
+	struct acpi_ec *ec =
+		acpi_driver_data(to_acpi_device(dev));
+
+	acpi_ec_leave_noirq(ec);
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops acpi_ec_pm = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(acpi_ec_suspend_noirq, acpi_ec_resume_noirq)
+};
+
 static int param_set_event_clearing(const char *val, struct kernel_param *kp)
 {
 	int result = 0;
@@ -1658,6 +1710,7 @@ static struct acpi_driver acpi_ec_driver = {
 		.add = acpi_ec_add,
 		.remove = acpi_ec_remove,
 		},
+	.drv.pm = &acpi_ec_pm,
 };
 
 int __init acpi_ec_init(void)
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 940218f..6996121 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -174,6 +174,8 @@ struct acpi_ec {
 	struct work_struct work;
 	unsigned long timestamp;
 	unsigned long nr_pending_queries;
+	bool saved_busy_polling;
+	unsigned int saved_polling_guard;
 };
 
 extern struct acpi_ec *first_ec;
-- 
1.7.10