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From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux PM <linux-pm@vger.kernel.org>
Cc: Len Brown <len.brown@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Zhang Rui <rui.zhang@intel.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Chen Yu <yu.c.chen@intel.com>
Subject: [PATCH 2/9] intel_idle: Clean up definitions of cpuidle callbacks
Date: Thu, 13 Feb 2020 22:59:56 +0100	[thread overview]
Message-ID: <1923258.fxMWiWM92A@kreacher> (raw)
In-Reply-To: <2960689.qre192dJKD@kreacher>

From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

Add proper kerneldoc descriptions to intel_idle() and
intel_idle_s2idle(), annotate the latter with __cpuidle and
reorder the declarations of local variables in both of them to
reflect the mwait_idle_with_hints() arguments order.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/idle/intel_idle.c | 39 +++++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 8d66efc53b89..5adc058c705d 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -892,19 +892,28 @@ static struct cpuidle_state dnv_cstates[] = {
 };
 
 /**
- * intel_idle
- * @dev: cpuidle_device
- * @drv: cpuidle driver
- * @index: index of cpuidle state
+ * intel_idle - Ask the processor to enter the given idle state.
+ * @dev: cpuidle device of the target CPU.
+ * @drv: cpuidle driver (assumed to point to intel_idle_driver).
+ * @index: Target idle state index.
+ *
+ * Use the MWAIT instruction to notify the processor that the CPU represented by
+ * @dev is idle and it can try to enter the idle state corresponding to @index.
+ *
+ * If the local APIC timer is not known to be reliable in the target idle state,
+ * enable one-shot tick broadcasting for the target CPU before executing MWAIT.
+ *
+ * Optionally call leave_mm() for the target CPU upfront to avoid wakeups due to
+ * flushing user TLBs.
  *
  * Must be called under local_irq_disable().
  */
 static __cpuidle int intel_idle(struct cpuidle_device *dev,
 				struct cpuidle_driver *drv, int index)
 {
-	unsigned long ecx = 1; /* break on interrupt flag */
 	struct cpuidle_state *state = &drv->states[index];
 	unsigned long eax = flg2MWAIT(state->flags);
+	unsigned long ecx = 1; /* break on interrupt flag */
 	bool uninitialized_var(tick);
 	int cpu = smp_processor_id();
 
@@ -937,16 +946,22 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
 }
 
 /**
- * intel_idle_s2idle - simplified "enter" callback routine for suspend-to-idle
- * @dev: cpuidle_device
- * @drv: cpuidle driver
- * @index: state index
+ * intel_idle_s2idle - Ask the processor to enter the given idle state.
+ * @dev: cpuidle device of the target CPU.
+ * @drv: cpuidle driver (assumed to point to intel_idle_driver).
+ * @index: Target idle state index.
+ *
+ * Use the MWAIT instruction to notify the processor that the CPU represented by
+ * @dev is idle and it can try to enter the idle state corresponding to @index.
+ *
+ * Invoked as a suspend-to-idle callback routine with frozen user space, frozen
+ * scheduler tick and suspended scheduler clock on the target CPU.
  */
-static void intel_idle_s2idle(struct cpuidle_device *dev,
-			     struct cpuidle_driver *drv, int index)
+static __cpuidle void intel_idle_s2idle(struct cpuidle_device *dev,
+					struct cpuidle_driver *drv, int index)
 {
-	unsigned long ecx = 1; /* break on interrupt flag */
 	unsigned long eax = flg2MWAIT(drv->states[index].flags);
+	unsigned long ecx = 1; /* break on interrupt flag */
 
 	mwait_idle_with_hints(eax, ecx);
 }
-- 
2.16.4






  parent reply	other threads:[~2020-02-13 22:05 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-13 21:58 [PATCH 0/9] intel_idle: More assorted cleanups Rafael J. Wysocki
2020-02-13 21:59 ` [PATCH 1/9] intel_idle: Simplify LAPIC timer reliability checks Rafael J. Wysocki
2020-02-13 21:59 ` Rafael J. Wysocki [this message]
2020-02-13 22:00 ` [PATCH 3/9] intel_idle: Relocate definitions of cpuidle callbacks Rafael J. Wysocki
2020-05-23  0:04   ` Qian Cai
2020-02-13 22:01 ` [PATCH 4/9] intel_idle: Add __initdata annotations to init time variables Rafael J. Wysocki
2020-02-13 22:01 ` [PATCH 5/9] intel_idle: Annotate init time data structures Rafael J. Wysocki
2020-02-13 22:02 ` [PATCH 6/9] intel_idle: Reorder declarations of static variables Rafael J. Wysocki
2020-02-13 22:03 ` [PATCH 7/9] intel_idle: Clean up kerneldoc comments of multiple functions Rafael J. Wysocki
2020-02-13 22:03 ` [PATCH 8/9] intel_idle: Define CPUIDLE_FLAG_TLB_FLUSHED as BIT(16) Rafael J. Wysocki
2020-02-13 22:04 ` [PATCH 9/9] intel_idle: Update copyright notice, known limitations and version Rafael J. Wysocki

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