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Date:   Thu, 21 Oct 2021 19:20:48 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Petr Benes <petrben@...il.com>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Michal Vokáč <michal.vokac@...ft.com>,
        linux-pm@...r.kernel.org, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Amit Kucheria <amitk@...nel.org>, linux-kernel@...r.kernel.org,
        Andrzej Pietrasiewicz <andrzej.p@...labora.com>,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        David Jander <david@...tonic.nl>,
        Zhang Rui <rui.zhang@...el.com>,
        Fabio Estevam <festevam@...il.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2] thermal: imx: implement runtime PM support

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@...gutronix.de> 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()?

How exactly did you reproduce it? Even more or less understanding how
this can potentially happen, i never had this issue on my HW. Is it something
HW specific?

Even after executing this command:
echo disabled > /sys/class/thermal/thermal_zone0/mode
cat /sys/class/thermal/thermal_zone0/temp

In this case, IRQ is disabled and on each manual temp read, driver starts
actively using runtime PM. I still never get (val & soc_data->temp_valid_mask)
== 0)..

> >
> > 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@...gutronix.de>
> > > ---
> > >  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 |

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