On Tuesday, October 30, 2012 04:53:28 PM Aaron Lu wrote:

On 09/29/2012 05:55 AM, Rafael J. Wysocki wrote:

quoted

Define two device PM QoS flags, PM_QOS_FLAG_NO_POWER_OFF
and PM_QOS_FLAG_REMOTE_WAKEUP, and introduce routines
dev_pm_qos_expose_flags() and dev_pm_qos_hide_flags() allowing the
caller to expose those two flags to user space or to hide them
from it, respectively.

After the flags have been exposed, user space will see two
additional sysfs attributes, pm_qos_no_power_off and
pm_qos_remote_wakeup, under the device's /sys/devices/.../power/
directory.  Then, writing 1 to one of them will update the
PM QoS flags request owned by user space so that the corresponding
flag is requested to be set.  In turn, writing 0 to one of them
will cause the corresponding flag in the user space's request to
be cleared (however, the owners of the other PM QoS flags requests
for the same device may still request the flag to be set and it
may be effectively set even if user space doesn't request that).

Signed-off-by: Rafael J. Wysocki <redacted>
---
 Documentation/ABI/testing/sysfs-devices-power |   31 ++++
 drivers/base/power/power.h                    |    6 
 drivers/base/power/qos.c                      |  169 ++++++++++++++++++++------
 drivers/base/power/sysfs.c                    |   95 +++++++++++++-
 include/linux/pm.h                            |    1 
 include/linux/pm_qos.h                        |   26 ++++
 6 files changed, 280 insertions(+), 48 deletions(-)

Index: linux/drivers/base/power/qos.c
===================================================================

--- linux.orig/drivers/base/power/qos.c
+++ linux/drivers/base/power/qos.c

@@ -40,6 +40,7 @@
 #include <linux/device.h>
 #include <linux/mutex.h>
 #include <linux/export.h>
+#include <linux/pm_runtime.h>
 
 #include "power.h"
 

@@ -322,6 +323,38 @@ int dev_pm_qos_add_request(struct device
 EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
 
 /**
+ * __dev_pm_qos_update_request - Modify an existing device PM QoS request.
+ * @req : PM QoS request to modify.
+ * @new_value: New value to request.
+ */
+int __dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value)
+{
+	s32 curr_value;
+	int ret = 0;
+
+	if (!req->dev->power.qos) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	switch(req->type) {
+	case DEV_PM_QOS_LATENCY:
+		curr_value = req->data.pnode.prio;
+		break;
+	case DEV_PM_QOS_FLAGS:
+		curr_value = req->data.flr.flags;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (curr_value != new_value)
+		ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
+
+	return ret;
+}
+
+/**
  * dev_pm_qos_update_request - modifies an existing qos request
  * @req : handle to list element holding a dev_pm_qos request to use
  * @new_value: defines the qos request

@@ -336,11 +369,9 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_add_request
  * -EINVAL in case of wrong parameters, -ENODEV if the device has been
  * removed from the system
  */
-int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
-			      s32 new_value)
+int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value)
 {
-	s32 curr_value;
-	int ret = 0;
+	int ret;
 
 	if (!req) /*guard against callers passing in null */
 		return -EINVAL;

@@ -350,29 +381,9 @@ int dev_pm_qos_update_request(struct dev
 		return -EINVAL;
 
 	mutex_lock(&dev_pm_qos_mtx);
-
-	if (!req->dev->power.qos) {
-		ret = -ENODEV;
-		goto out;
-	}
-
-	switch(req->type) {
-	case DEV_PM_QOS_LATENCY:
-		curr_value = req->data.pnode.prio;
-		break;
-	case DEV_PM_QOS_FLAGS:
-		curr_value = req->data.flr.flags;
-		break;
-	default:
-		ret = -EINVAL;
-		goto out;
-	}
-
-	if (curr_value != new_value)
-		ret = apply_constraint(req, PM_QOS_UPDATE_REQ, new_value);
-
- out:
+	__dev_pm_qos_update_request(req, new_value);

You forgot to assign the return value here.

Quite obviously.  I'm going to apply the appended patch for that.

Thanks for spotting it!

Rafael


---
From: Rafael J. Wysocki <redacted>
Subject: PM / QoS: Fix the return value of dev_pm_qos_update_request()

Commit e39473d (PM / QoS: Make it possible to expose PM QoS device)
flags to user space introduced __dev_pm_qos_update_request() to be
called internally by dev_pm_qos_update_request(), but forgot to make
the latter actually use the return value of the former.  Fix this
mistake.

Signed-off-by: Rafael J. Wysocki <redacted>
---
 drivers/base/power/qos.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux/drivers/base/power/qos.c
===================================================================

--- linux.orig/drivers/base/power/qos.c
+++ linux/drivers/base/power/qos.c

@@ -380,7 +380,7 @@ int dev_pm_qos_update_request(struct dev
 		return -EINVAL;
 
 	mutex_lock(&dev_pm_qos_mtx);
-	__dev_pm_qos_update_request(req, new_value);
+	ret = __dev_pm_qos_update_request(req, new_value);
 	mutex_unlock(&dev_pm_qos_mtx);
 
 	return ret;

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.