Re: [RFC PATCH 1/2] iio: pm_runtime: Introduce PM runtime helper functions

Adding linux-pm people since Lars suggested that the changes should be
in the PM core.

I agree, that these changes are not "awfully" IIO specific but no
other subsystem uses
this pattern for configuration. In fact iio_pm_runtime_setup can be
done in many more
other ways depending on functionality needed.

On Mon, May 18, 2015 at 8:34 PM, Peter Meerwald [off-list ref] wrote:

On Mon, 18 May 2015, Daniel Baluta wrote:

quoted

We need this in order to avoid reimplementing the same functions each time
we add PM runtime support in a driver.

comments below

quoted

Simple grep shows the following users:
      * accel/mma9551.c
      * accel/mmc9553.c
      * accel/kxcjk1013.c
      * accel/bmc150-accel.c
      * gyro/bmg160.c
      * imu/kmx61.c
      * common/hid-sensors.

Signed-off-by: Daniel Baluta <redacted>
---
 include/linux/iio/pm_runtime.h | 63 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 include/linux/iio/pm_runtime.h

diff --git a/include/linux/iio/pm_runtime.h b/include/linux/iio/pm_runtime.h
new file mode 100644
index 0000000..dc2bca7
--- /dev/null
+++ b/include/linux/iio/pm_runtime.h

@@ -0,0 +1,63 @@
+/*
+ * Industrial I/O runtime PM helper functions
+ *
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License.  See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ */
+#ifndef __IIO_PM_RUNTIME
+#define __IIO_PM_RUNTIME
+
+#include <linux/pm_runtime.h>
+
+static inline int iio_pm_runtime_setup(struct device *dev, int delay,
+                                    bool ignore_children)
+{
+     int ret;
+
+     ret = pm_runtime_set_active(dev);
+     if (ret)

just noting: should this be (ret) or (ret < 0)?

pm_runtime_get_sync() below may return negative, 0, and positive
pm_runtime_set_active() seems to return negative or 0

documentation doesn't tell... wondering if (ret < 0) would be safer here?

I think this check is correct, I also found the same check in
power/pm2301_charger.c:1116. But there is no problem to add if (ret < 0)
it looks safer.

quoted

+             return ret;
+
+     pm_suspend_ignore_children(dev, ignore_children);
+     pm_runtime_enable(dev);
+     pm_runtime_set_autosuspend_delay(dev, delay);
+     pm_runtime_use_autosuspend(dev);
+
+     return 0;
+}
+
+static inline void iio_pm_runtime_cleanup(struct device *dev)
+{
+     pm_runtime_disable(dev);
+     pm_runtime_set_suspended(dev);
+     pm_runtime_put_noidle(dev);
+}
+
+static inline int iio_pm_runtime_set_power(struct device *dev, bool on)

why a static inline function in a header file?
these functions do not seem to be performance critical and are substantial
enough in size to avoid copying the code to every driver

I know about this, but I was trying to avoid another .config option
that each IIO driver should select when implementing runtime pm support.

I can change this.

quoted

+{
+#ifdef CONFIG_PM
+     int ret;
+
+     if (on)
+             ret = pm_runtime_get_sync(dev);
+     else {
+             pm_runtime_mark_last_busy(dev);
+             ret = pm_runtime_put_autosuspend(dev);
+     }
+
+     if (ret < 0) {
+             dev_err(dev, "Failed: iio_set_power_state for %d\n", on);

the error message doesn't match the function name, the text, 'for %d', is
not very clear

Correct. Thanks for spotting this!

quoted

+             if (on)
+                     pm_runtime_put_noidle(dev);
+
+             return ret;
+     }
+#endif
+     return 0;
+}
+
+#endif /* __IIO_PM_RUNTIME */

--

Peter Meerwald
+43-664-2444418 (mobile)
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