Re: [PATCH v2] thermal: imx: implement runtime PM support

From: Oleksij Rempel
Date: Thu Oct 21 2021 - 03:20:24 EST

Hi Petr,

On Wed, Oct 20, 2021 at 05:53:03PM +0200, Petr Benes wrote:
> On Wed, 20 Oct 2021 at 07:05, Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> wrote:
> >
> > Hi Petr and Michal,
> >
> > I forgot to add you for v2 in CC. Please test/review this version.
>
> Hi Oleksij,
>
> It works good. with PM as well as without PM. The only minor issue I found is,
> that the first temperature reading (when the driver probes) fails. That is
> (val & soc_data->temp_valid_mask) == 0) holds true. How does
> pm_runtime_resume_and_get() behave in imx_thermal_probe()?
> Does it go through imx_thermal_runtime_resume() with usleep_range()?

On the first temperature reading, the PM and part of HW is not
initialized. Current probe sequence is racy and has at least following
issues:
- thermal_zone_device_register is executed before HW init was completed.
It kind of worked before my patch, becaus part of reinit was done by
temperature init. It worked, since the irq_enabled flag was not set,
but potentially would run enable_irq() two times if device is
overheated on probe.
- the imx_thermal core is potentially disable after first race
condition:
CPU0 CPU1
thermal_zone_device_register()
imx_get_temp()
irq_enabled == false
power_up
read_temp
power_up
power_down
irq_enabled = true;

... at this point imx_thermal is powered down for some amount of time,
over temperature IRQ will not be triggered for some amount of time.

- if some part after thermal_zone_device_register() would fail or
deferred, the worker polling temperature will run in to NULL pointer.
This issue already happened...

After migrating to runtime PM, one of issues started to be visible even
on normal conditions.
I'll send one more patch with reworking probe sequence.

> >
> > On Tue, Oct 19, 2021 at 03:08:09PM +0200, Oleksij Rempel wrote:
> > > Starting with commit d92ed2c9d3ff ("thermal: imx: Use driver's local
> > > data to decide whether to run a measurement") this driver stared using
> > > irq_enabled flag to make decision to power on/off the thermal core. This
> > > triggered a regression, where after reaching critical temperature, alarm
> > > IRQ handler set irq_enabled to false, disabled thermal core and was not
> > > able read temperature and disable cooling sequence.
> > >
> > > In case the cooling device is "CPU/GPU freq", the system will run with
> > > reduce performance until next reboot.
> > >
> > > To solve this issue, we need to move all parts implementing hand made
> > > runtime power management and let it handle actual runtime PM framework.
> > >
> > > Fixes: d92ed2c9d3ff ("thermal: imx: Use driver's local data to decide whether to run a measurement")
> > > Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
> > > ---
> > > drivers/thermal/imx_thermal.c | 143 +++++++++++++++++++++-------------
> > > 1 file changed, 89 insertions(+), 54 deletions(-)
> > >
> > > diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
> > > index 2c7473d86a59..cb5a4354fc75 100644
> > > --- a/drivers/thermal/imx_thermal.c
> > > +++ b/drivers/thermal/imx_thermal.c
> > > @@ -15,6 +15,7 @@
> > > #include <linux/regmap.h>
> > > #include <linux/thermal.h>
> > > #include <linux/nvmem-consumer.h>
> > > +#include <linux/pm_runtime.h>
> > >
> > > #define REG_SET 0x4
> > > #define REG_CLR 0x8
> > > @@ -194,6 +195,7 @@ static struct thermal_soc_data thermal_imx7d_data = {
> > > };
> > >
> > > struct imx_thermal_data {
> > > + struct device *dev;
> > > struct cpufreq_policy *policy;
> > > struct thermal_zone_device *tz;
> > > struct thermal_cooling_device *cdev;
> > > @@ -252,44 +254,15 @@ static int imx_get_temp(struct thermal_zone_device *tz, int *temp)
> > > const struct thermal_soc_data *soc_data = data->socdata;
> > > struct regmap *map = data->tempmon;
> > > unsigned int n_meas;
> > > - bool wait, run_measurement;
> > > u32 val;
> > > + int ret;
> > >
> > > - run_measurement = !data->irq_enabled;
> > > - if (!run_measurement) {
> > > - /* Check if a measurement is currently in progress */
> > > - regmap_read(map, soc_data->temp_data, &val);
> > > - wait = !(val & soc_data->temp_valid_mask);
> > > - } else {
> > > - /*
> > > - * Every time we measure the temperature, we will power on the
> > > - * temperature sensor, enable measurements, take a reading,
> > > - * disable measurements, power off the temperature sensor.
> > > - */
> > > - regmap_write(map, soc_data->sensor_ctrl + REG_CLR,
> > > - soc_data->power_down_mask);
> > > - regmap_write(map, soc_data->sensor_ctrl + REG_SET,
> > > - soc_data->measure_temp_mask);
> > > -
> > > - wait = true;
> > > - }
> > > -
> > > - /*
> > > - * According to the temp sensor designers, it may require up to ~17us
> > > - * to complete a measurement.
> > > - */
> > > - if (wait)
> > > - usleep_range(20, 50);
> > > + ret = pm_runtime_resume_and_get(data->dev);
> > > + if (ret < 0)
> > > + return ret;
> > >
> > > regmap_read(map, soc_data->temp_data, &val);
> > >
> > > - if (run_measurement) {
> > > - regmap_write(map, soc_data->sensor_ctrl + REG_CLR,
> > > - soc_data->measure_temp_mask);
> > > - regmap_write(map, soc_data->sensor_ctrl + REG_SET,
> > > - soc_data->power_down_mask);
> > > - }
> > > -
> > > if ((val & soc_data->temp_valid_mask) == 0) {
> > > dev_dbg(&tz->device, "temp measurement never finished\n");
> > > return -EAGAIN;
> > > @@ -328,6 +301,8 @@ static int imx_get_temp(struct thermal_zone_device *tz, int *temp)
> > > enable_irq(data->irq);
> > > }
> > >
> > > + pm_runtime_put(data->dev);
> > > +
> > > return 0;
> > > }
> > >
> > > @@ -335,24 +310,16 @@ static int imx_change_mode(struct thermal_zone_device *tz,
> > > enum thermal_device_mode mode)
> > > {
> > > struct imx_thermal_data *data = tz->devdata;
> > > - struct regmap *map = data->tempmon;
> > > - const struct thermal_soc_data *soc_data = data->socdata;
> > >
> > > if (mode == THERMAL_DEVICE_ENABLED) {
> > > - regmap_write(map, soc_data->sensor_ctrl + REG_CLR,
> > > - soc_data->power_down_mask);
> > > - regmap_write(map, soc_data->sensor_ctrl + REG_SET,
> > > - soc_data->measure_temp_mask);
> > > + pm_runtime_get(data->dev);
> > >
> > > if (!data->irq_enabled) {
> > > data->irq_enabled = true;
> > > enable_irq(data->irq);
> > > }
> > > } else {
> > > - regmap_write(map, soc_data->sensor_ctrl + REG_CLR,
> > > - soc_data->measure_temp_mask);
> > > - regmap_write(map, soc_data->sensor_ctrl + REG_SET,
> > > - soc_data->power_down_mask);
> > > + pm_runtime_put(data->dev);
> > >
> > > if (data->irq_enabled) {
> > > disable_irq(data->irq);
> > > @@ -393,6 +360,11 @@ static int imx_set_trip_temp(struct thermal_zone_device *tz, int trip,
> > > int temp)
> > > {
> > > struct imx_thermal_data *data = tz->devdata;
> > > + int ret;
> > > +
> > > + ret = pm_runtime_resume_and_get(data->dev);
> > > + if (ret < 0)
> > > + return ret;
> > >
> > > /* do not allow changing critical threshold */
> > > if (trip == IMX_TRIP_CRITICAL)
> > > @@ -406,6 +378,8 @@ static int imx_set_trip_temp(struct thermal_zone_device *tz, int trip,
> > >
> > > imx_set_alarm_temp(data, temp);
> > >
> > > + pm_runtime_put(data->dev);
> > > +
> > > return 0;
> > > }
> > >
> > > @@ -681,6 +655,8 @@ static int imx_thermal_probe(struct platform_device *pdev)
> > > if (!data)
> > > return -ENOMEM;
> > >
> > > + data->dev = &pdev->dev;
> > > +
> > > map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "fsl,tempmon");
> > > if (IS_ERR(map)) {
> > > ret = PTR_ERR(map);
> > > @@ -801,6 +777,14 @@ static int imx_thermal_probe(struct platform_device *pdev)
> > > regmap_write(map, data->socdata->sensor_ctrl + REG_SET,
> > > data->socdata->measure_temp_mask);
> > >
> > > + /* the core was configured and enabled just before */
> > > + pm_runtime_set_active(&pdev->dev);
> > > + pm_runtime_enable(data->dev);
> > > +
> > > + ret = pm_runtime_resume_and_get(data->dev);
> > > + if (ret < 0)
> > > + goto disable_runtime_pm;
> > > +
> > > data->irq_enabled = true;
> > > ret = thermal_zone_device_enable(data->tz);
> > > if (ret)
> > > @@ -814,10 +798,15 @@ static int imx_thermal_probe(struct platform_device *pdev)
> > > goto thermal_zone_unregister;
> > > }
> > >
> > > + pm_runtime_put(data->dev);
> > > +
> > > return 0;
> > >
> > > thermal_zone_unregister:
> > > thermal_zone_device_unregister(data->tz);
> > > +disable_runtime_pm:
> > > + pm_runtime_put_noidle(data->dev);
> > > + pm_runtime_disable(data->dev);
> > > clk_disable:
> > > clk_disable_unprepare(data->thermal_clk);
> > > legacy_cleanup:
> > > @@ -829,13 +818,9 @@ static int imx_thermal_probe(struct platform_device *pdev)
> > > static int imx_thermal_remove(struct platform_device *pdev)
> > > {
> > > struct imx_thermal_data *data = platform_get_drvdata(pdev);
> > > - struct regmap *map = data->tempmon;
> > >
> > > - /* Disable measurements */
> > > - regmap_write(map, data->socdata->sensor_ctrl + REG_SET,
> > > - data->socdata->power_down_mask);
> > > - if (!IS_ERR(data->thermal_clk))
> > > - clk_disable_unprepare(data->thermal_clk);
> > > + pm_runtime_put_noidle(data->dev);
> > > + pm_runtime_disable(data->dev);
> > >
> > > thermal_zone_device_unregister(data->tz);
> > > imx_thermal_unregister_legacy_cooling(data);
> > > @@ -858,29 +843,79 @@ static int __maybe_unused imx_thermal_suspend(struct device *dev)
> > > ret = thermal_zone_device_disable(data->tz);
> > > if (ret)
> > > return ret;
> > > +
> > > + return pm_runtime_force_suspend(data->dev);
> > > +}
> > > +
> > > +static int __maybe_unused imx_thermal_resume(struct device *dev)
> > > +{
> > > + struct imx_thermal_data *data = dev_get_drvdata(dev);
> > > + int ret;
> > > +
> > > + ret = pm_runtime_force_resume(data->dev);
> > > + if (ret)
> > > + return ret;
> > > + /* Enabled thermal sensor after resume */
> > > + return thermal_zone_device_enable(data->tz);
> > > +}
> > > +
> > > +static int __maybe_unused imx_thermal_runtime_suspend(struct device *dev)
> > > +{
> > > + struct imx_thermal_data *data = dev_get_drvdata(dev);
> > > + const struct thermal_soc_data *socdata = data->socdata;
> > > + struct regmap *map = data->tempmon;
> > > + int ret;
> > > +
> > > + ret = regmap_write(map, socdata->sensor_ctrl + REG_CLR,
> > > + socdata->measure_temp_mask);
> > > + if (ret)
> > > + return ret;
> > > +
> > > + ret = regmap_write(map, socdata->sensor_ctrl + REG_SET,
> > > + socdata->power_down_mask);
> > > + if (ret)
> > > + return ret;
> > > +
> > > clk_disable_unprepare(data->thermal_clk);
> > >
> > > return 0;
> > > }
> > >
> > > -static int __maybe_unused imx_thermal_resume(struct device *dev)
> > > +static int __maybe_unused imx_thermal_runtime_resume(struct device *dev)
> > > {
> > > struct imx_thermal_data *data = dev_get_drvdata(dev);
> > > + const struct thermal_soc_data *socdata = data->socdata;
> > > + struct regmap *map = data->tempmon;
> > > int ret;
> > >
> > > ret = clk_prepare_enable(data->thermal_clk);
> > > if (ret)
> > > return ret;
> > > - /* Enabled thermal sensor after resume */
> > > - ret = thermal_zone_device_enable(data->tz);
> > > +
> > > + ret = regmap_write(map, socdata->sensor_ctrl + REG_CLR,
> > > + socdata->power_down_mask);
> > > + if (ret)
> > > + return ret;
> > > +
> > > + ret = regmap_write(map, socdata->sensor_ctrl + REG_SET,
> > > + socdata->measure_temp_mask);
> > > if (ret)
> > > return ret;
> > >
> > > + /*
> > > + * According to the temp sensor designers, it may require up to ~17us
> > > + * to complete a measurement.
> > > + */
> > > + usleep_range(20, 50);
> > > +
> > > return 0;
> > > }
> > >
> > > -static SIMPLE_DEV_PM_OPS(imx_thermal_pm_ops,
> > > - imx_thermal_suspend, imx_thermal_resume);
> > > +static const struct dev_pm_ops imx_thermal_pm_ops = {
> > > + SET_SYSTEM_SLEEP_PM_OPS(imx_thermal_suspend, imx_thermal_resume)
> > > + SET_RUNTIME_PM_OPS(imx_thermal_runtime_suspend,
> > > + imx_thermal_runtime_resume, NULL)
> > > +};
> > >
> > > static struct platform_driver imx_thermal = {
> > > .driver = {
> > > --
> > > 2.30.2
> > >
> > >
> >
> > --
> > Pengutronix e.K. | |
> > Steuerwalder Str. 21 | http://www.pengutronix.de/ |
> > 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
> > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
>

--
Pengutronix e.K. | |
Steuerwalder Str. 21 | http://www.pengutronix.de/ |
31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |