Re: [lm-sensors] [RFC PATCH 1/9] hwmon: lis3: pm_runtime support

Jonathan Cameron
2010-10-03T11:18:54Z

On 10/03/10 06:03, Onkalo Samu wrote:
>
> Thanks for comments.
>
> On Sat, 2010-10-02 at 19:14 +0200, ext Jonathan Cameron wrote:
>> On 10/01/10 12:46, Samu Onkalo wrote:
>>> Add pm_runtime support to lis3 core driver.
>>> Add pm_runtime support to lis3 i2c driver.
>>>
>>> spi and hp_accel drivers are not yet supported. Old always
>>> on functionality remains for those.
>>>
>>> For sysfs there is 5 second delay before turning off the
>>> chip to avoid long ramp up delay.
>> I'm not overly familiar with the runtime stuff so looking at this based
>> on a quick read of their documentation.
>>
>> Note I'm also not that familiar with the driver :)
>>
>> One real query about the logic in lis3lv02d_i2c_resume. My reading is
>> that if we are runtime suspended when coming out of a system suspend
>> then we don't want to power up the chip? However I'm not entirely
>> sure how the two types of power management interact so sorry if I
>> have completely misunderstood this!
>>
>
> It took some time understand how this system works over the system level
> suspend. And depending on the use, lis3 chip can be kept active or
> powered down over the system standby :)
The answer below covers my query (and is a handy thing to know about in
general so thanks for that!) I'll certainly be copying this code for
some of my drivers when I have the time to play with runtime pm.

Acked-by: Jonathan Cameron <jic23-KWPb1pKIrIJaa/9Udqfwiw@public.gmane.org>
>
>
>> Jonathan
>>>
>>> Signed-off-by: Samu Onkalo <samu.p.onkalo-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org>
>>> ---
>>> drivers/hwmon/lis3lv02d.c | 59 +++++++++++++++++++++++++++++++++++++++++
>>> drivers/hwmon/lis3lv02d.h | 1 +
>>> drivers/hwmon/lis3lv02d_i2c.c | 48 +++++++++++++++++++++++++--------
>>> 3 files changed, 96 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/hwmon/lis3lv02d.c b/drivers/hwmon/lis3lv02d.c
>>> index fc591ae..eaa5bf0 100644
>>> --- a/drivers/hwmon/lis3lv02d.c
>>> +++ b/drivers/hwmon/lis3lv02d.c
>>> @@ -34,6 +34,7 @@
>>> #include <linux/freezer.h>
>>> #include <linux/uaccess.h>
>>> #include <linux/miscdevice.h>
>>> +#include <linux/pm_runtime.h>
>>> #include <asm/atomic.h>
>>> #include "lis3lv02d.h"
>>>
>>> @@ -43,6 +44,9 @@
>>> #define MDPS_POLL_INTERVAL 50
>>> #define MDPS_POLL_MIN 0
>>> #define MDPS_POLL_MAX 2000
>>> +
>>> +#define SYSFS_POWERDOWN_DELAY 5000 /* In milliseconds */
>> Name is rather generic...
>>> +
>>> /*
>>> * The sensor can also generate interrupts (DRDY) but it's pretty pointless
>>> * because they are generated even if the data do not change. So it's better
>>> @@ -262,6 +266,18 @@ static void lis3lv02d_joystick_poll(struct input_polled_dev *pidev)
>>> mutex_unlock(&lis3_dev.mutex);
>>> }
>>>
>>> +static void lis3lv02d_joystick_open(struct input_polled_dev *pidev)
>>> +{
>>> + if (lis3_dev.pm_dev)
>>> + pm_runtime_get_sync(lis3_dev.pm_dev);
>>> +}
>>> +
>>> +static void lis3lv02d_joystick_close(struct input_polled_dev *pidev)
>>> +{
>>> + if (lis3_dev.pm_dev)
>>> + pm_runtime_put(lis3_dev.pm_dev);
>>> +}
>>> +
>>> static irqreturn_t lis302dl_interrupt(int irq, void *dummy)
>>> {
>>> if (!test_bit(0, &lis3_dev.misc_opened))
>>> @@ -356,6 +372,9 @@ static int lis3lv02d_misc_open(struct inode *inode, struct file *file)
>>> if (test_and_set_bit(0, &lis3_dev.misc_opened))
>>> return -EBUSY; /* already open */
>>>
>>> + if (lis3_dev.pm_dev)
>>> + pm_runtime_get_sync(lis3_dev.pm_dev);
>>> +
>>> atomic_set(&lis3_dev.count, 0);
>>> return 0;
>>> }
>>> @@ -364,6 +383,8 @@ static int lis3lv02d_misc_release(struct inode *inode, struct file *file)
>>> {
>>> fasync_helper(-1, file, 0, &lis3_dev.async_queue);
>>> clear_bit(0, &lis3_dev.misc_opened); /* release the device */
>>> + if (lis3_dev.pm_dev)
>>> + pm_runtime_put(lis3_dev.pm_dev);
>>> return 0;
>>> }
>>>
>>> @@ -460,6 +481,8 @@ int lis3lv02d_joystick_enable(void)
>>> return -ENOMEM;
>>>
>>> lis3_dev.idev->poll = lis3lv02d_joystick_poll;
>>> + lis3_dev.idev->open = lis3lv02d_joystick_open;
>>> + lis3_dev.idev->close = lis3lv02d_joystick_close;
>>> lis3_dev.idev->poll_interval = MDPS_POLL_INTERVAL;
>>> lis3_dev.idev->poll_interval_min = MDPS_POLL_MIN;
>>> lis3_dev.idev->poll_interval_max = MDPS_POLL_MAX;
>>> @@ -512,12 +535,30 @@ void lis3lv02d_joystick_disable(void)
>>> EXPORT_SYMBOL_GPL(lis3lv02d_joystick_disable);
>>>
>>> /* Sysfs stuff */
>>> +static void lis3lv02d_sysfs_poweron(struct lis3lv02d *lis3)
>>> +{
>>> + /*
>>> + * SYSFS functions are fast visitors so put-call
>>> + * immediately after the get-call. However, keep
>>> + * chip running for a while and schedule delayed
>>> + * suspend. This way periodic sysfs calls doesn't
>>> + * suffer from relatively long power up time.
>>> + */
>>> +
>>> + if (lis3_dev.pm_dev) {
>>> + pm_runtime_get_sync(lis3->pm_dev);
>>> + pm_runtime_put_noidle(lis3->pm_dev);
>>> + pm_schedule_suspend(lis3->pm_dev, SYSFS_POWERDOWN_DELAY);
>>> + }
>>> +}
>>> +
>>> static ssize_t lis3lv02d_selftest_show(struct device *dev,
>>> struct device_attribute *attr, char *buf)
>>> {
>>> int result;
>>> s16 values[3];
>>>
>>> + lis3lv02d_sysfs_poweron(&lis3_dev);
>>> result = lis3lv02d_selftest(&lis3_dev, values);
>>> return sprintf(buf, "%s %d %d %d\n", result == 0 ? "OK" : "FAIL",
>>> values[0], values[1], values[2]);
>>> @@ -528,6 +569,7 @@ static ssize_t lis3lv02d_position_show(struct device *dev,
>>> {
>>> int x, y, z;
>>>
>>> + lis3lv02d_sysfs_poweron(&lis3_dev);
>>> mutex_lock(&lis3_dev.mutex);
>>> lis3lv02d_get_xyz(&lis3_dev, &x, &y, &z);
>>> mutex_unlock(&lis3_dev.mutex);
>>> @@ -549,6 +591,7 @@ static ssize_t lis3lv02d_rate_set(struct device *dev,
>>> if (strict_strtoul(buf, 0, &rate))
>>> return -EINVAL;
>>>
>>> + lis3lv02d_sysfs_poweron(&lis3_dev);
>>> if (lis3lv02d_set_odr(rate))
>>> return -EINVAL;
>>>
>>> @@ -585,6 +628,17 @@ int lis3lv02d_remove_fs(struct lis3lv02d *lis3)
>>> {
>>> sysfs_remove_group(&lis3->pdev->dev.kobj, &lis3lv02d_attribute_group);
>>> platform_device_unregister(lis3->pdev);
>>> + if (lis3_dev.pm_dev) {
>>> + /* Barrier after the sysfs remove */
>>> + pm_runtime_barrier(lis3->pm_dev);
>>> +
>>> + /* SYSFS may have left chip running. Turn off if necessary */
>>> + if (!pm_runtime_suspended(lis3->pm_dev))
>>> + lis3lv02d_poweroff(&lis3_dev);
>>> +
>>> + pm_runtime_disable(lis3->pm_dev);
>>> + pm_runtime_set_suspended(lis3->pm_dev);
>>> + }
>>> return 0;
>>> }
>>> EXPORT_SYMBOL_GPL(lis3lv02d_remove_fs);
>>> @@ -685,6 +739,11 @@ int lis3lv02d_init_device(struct lis3lv02d *dev)
>>> lis3lv02d_add_fs(dev);
>>> lis3lv02d_poweron(dev);
>>>
>>> + if (lis3_dev.pm_dev) {
>>> + pm_runtime_set_active(dev->pm_dev);
>>> + pm_runtime_enable(dev->pm_dev);
>>> + }
>>> +
>>> if (lis3lv02d_joystick_enable())
>>> printk(KERN_ERR DRIVER_NAME ": joystick initialization failed\n");
>>>
>>> diff --git a/drivers/hwmon/lis3lv02d.h b/drivers/hwmon/lis3lv02d.h
>>> index 8540913..3e8a208 100644
>>> --- a/drivers/hwmon/lis3lv02d.h
>>> +++ b/drivers/hwmon/lis3lv02d.h
>>> @@ -214,6 +214,7 @@ struct axis_conversion {
>>>
>>> struct lis3lv02d {
>>> void *bus_priv; /* used by the bus layer only */
>>> + struct device *pm_dev; /* for pm_runtime purposes */
>>> int (*init) (struct lis3lv02d *lis3);
>>> int (*write) (struct lis3lv02d *lis3, int reg, u8 val);
>>> int (*read) (struct lis3lv02d *lis3, int reg, u8 *ret);
>>> diff --git a/drivers/hwmon/lis3lv02d_i2c.c b/drivers/hwmon/lis3lv02d_i2c.c
>>> index 8e5933b..b9ed1fb 100644
>>> --- a/drivers/hwmon/lis3lv02d_i2c.c
>>> +++ b/drivers/hwmon/lis3lv02d_i2c.c
>>> @@ -29,6 +29,7 @@
>>> #include <linux/init.h>
>>> #include <linux/err.h>
>>> #include <linux/i2c.h>
>>> +#include <linux/pm_runtime.h>
>>> #include "lis3lv02d.h"
>>>
>>> #define DRV_NAME "lis3lv02d_i2c"
>>> @@ -95,6 +96,7 @@ static int __devinit lis3lv02d_i2c_probe(struct i2c_client *client,
>>> lis3_dev.write = lis3_i2c_write;
>>> lis3_dev.irq = client->irq;
>>> lis3_dev.ac = lis3lv02d_axis_map;
>>> + lis3_dev.pm_dev = &client->dev;
>>>
>>> i2c_set_clientdata(client, &lis3_dev);
>>> ret = lis3lv02d_init_device(&lis3_dev);
>>> @@ -111,14 +113,14 @@ static int __devexit lis3lv02d_i2c_remove(struct i2c_client *client)
>>> pdata->release_resources();
>>>
>>> lis3lv02d_joystick_disable();
>>> - lis3lv02d_poweroff(lis3);
>>>
>>> return lis3lv02d_remove_fs(&lis3_dev);
>>> }
>>>
>>> #ifdef CONFIG_PM
>>> -static int lis3lv02d_i2c_suspend(struct i2c_client *client, pm_message_t mesg)
>>> +static int lis3lv02d_i2c_suspend(struct device *dev)
>>> {
>>> + struct i2c_client *client = container_of(dev, struct i2c_client, dev);
>>> struct lis3lv02d *lis3 = i2c_get_clientdata(client);
>>>
>>> if (!lis3->pdata || !lis3->pdata->wakeup_flags)
>>> @@ -126,18 +128,16 @@ static int lis3lv02d_i2c_suspend(struct i2c_client *client, pm_message_t mesg)
>>> return 0;
>>> }
>>>
>>> -static int lis3lv02d_i2c_resume(struct i2c_client *client)
>>> +static int lis3lv02d_i2c_resume(struct device *dev)
>>> {
>>> + struct i2c_client *client = container_of(dev, struct i2c_client, dev);
>>> struct lis3lv02d *lis3 = i2c_get_clientdata(client);
>>>
>>> - if (!lis3->pdata || !lis3->pdata->wakeup_flags)
>>> + if (!lis3->pdata || !lis3->pdata->wakeup_flags ||
>>> + pm_runtime_suspended(dev))
>> I may be misunderstanding the docs on this, but I would have thought
>> we only want to power it up if it isn't in suspended state?
>
> That was what I also though, but ...
>
> runtime documentation says:
>
> "During system resume, devices generally should be brought back to full power,
> even if they were suspended before the system sleep began. There are several
> reasons for this, including:"
>
> And there was quite good reasons in the doc to do that :)
>
> I2C core code turns suspended child devices on. However, there are no users
> and pm_runtime notices that. Pm_runtime calls runtime_suspend-cb soon after the
> system level resume. If the chip is not powered up when that happens, it is possible
> that regulators are off and all the accesses towards the chip fails.
I guess that makes sense in a kind of roundabout way!
>
>
>
>
>
>>> lis3lv02d_poweron(lis3);
>>> - return 0;
>>> -}
>>>
>>> -static void lis3lv02d_i2c_shutdown(struct i2c_client *client)
>>> -{
>>> - lis3lv02d_i2c_suspend(client, PMSG_SUSPEND);
>>> + return 0;
>>> }
>>> #else
>>> #define lis3lv02d_i2c_suspend NULL
>>> @@ -145,6 +145,24 @@ static void lis3lv02d_i2c_shutdown(struct i2c_client *client)
>>> #define lis3lv02d_i2c_shutdown NULL
>>> #endif
>>>
>>> +static int lis3_i2c_runtime_suspend(struct device *dev)
>>> +{
>>> + struct i2c_client *client = container_of(dev, struct i2c_client, dev);
>>> + struct lis3lv02d *lis3 = i2c_get_clientdata(client);
>>> +
>>> + lis3lv02d_poweroff(lis3);
>>> + return 0;
>>> +}
>>> +
>>> +static int lis3_i2c_runtime_resume(struct device *dev)
>>> +{
>>> + struct i2c_client *client = container_of(dev, struct i2c_client, dev);
>>> + struct lis3lv02d *lis3 = i2c_get_clientdata(client);
>>> +
>>> + lis3lv02d_poweron(lis3);
>>> + return 0;
>>> +}
>>> +
>>> static const struct i2c_device_id lis3lv02d_id[] = {
>>> {"lis3lv02d", 0 },
>>> {}
>>> @@ -152,14 +170,20 @@ static const struct i2c_device_id lis3lv02d_id[] = {
>>>
>>> MODULE_DEVICE_TABLE(i2c, lis3lv02d_id);
>>>
>>> +static const struct dev_pm_ops lis3_pm_ops = {
>>> + SET_SYSTEM_SLEEP_PM_OPS(lis3lv02d_i2c_suspend,
>>> + lis3lv02d_i2c_resume)
>>> + SET_RUNTIME_PM_OPS(lis3_i2c_runtime_suspend,
>>> + lis3_i2c_runtime_resume,
>>> + NULL)
>>> +};
>>> +
>>> static struct i2c_driver lis3lv02d_i2c_driver = {
>>> .driver = {
>>> .name = DRV_NAME,
>>> .owner = THIS_MODULE,
>>> + .pm = &lis3_pm_ops,
>>> },
>>> - .suspend = lis3lv02d_i2c_suspend,
>>> - .shutdown = lis3lv02d_i2c_shutdown,
>>> - .resume = lis3lv02d_i2c_resume,
>>> .probe = lis3lv02d_i2c_probe,
>>> .remove = __devexit_p(lis3lv02d_i2c_remove),
>>> .id_table = lis3lv02d_id,
>>
>
>
>