Re: [PATCH] thermal: imx: Fix temperature measurements on i.MX6 after alarm

[Petr Benes]

On Mon, 18 Oct 2021 at 13:28, Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx> wrote:
>
> Hi Michal,
>
> I hope you have seen this patch:
> https://lore.kernel.org/all/20210924115032.29684-1-o.rempel@xxxxxxxxxxxxxx/
>
> Are there any reason why this was ignored?

Missed completely. It looks it addresses the problem more systematically.

>
> On Fri, Oct 08, 2021 at 10:11:37AM +0200, Michal Vokáč wrote:
> > From: Petr Beneš <petr.benes@xxxxxxxxx>
> >
> > SoC temperature readout may not work after thermal alarm fires interrupt.
> > This harms userspace as well as CPU cooling device.
> >
> > Two issues with the logic involved. First, there is no protection against
> > concurent measurements, hence one can switch the sensor off while
> > the other one tries to read temperature later. Second, the interrupt path
> > usually fails. At the end the sensor is powered off and thermal IRQ is
> > disabled. One has to reenable the thermal zone by the sysfs interface.
> >
> > Most of troubles come from commit d92ed2c9d3ff ("thermal: imx: Use
> > driver's local data to decide whether to run a measurement")
> >
> > It uses data->irq_enabled as the "local data". Indeed, its value is
> > related to the state of the sensor loosely under normal operation and,
> > frankly, gets unleashed when the thermal interrupt arrives.
> >
> > Current patch adds the "local data" (new member sensor_on in
> > imx_thermal_data) and sets its value in controlled manner.
> >
> > Fixes: d92ed2c9d3ff ("thermal: imx: Use driver's local data to decide whether to run a measurement")
> > Cc: petrben@xxxxxxxxx
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Petr Beneš <petr.benes@xxxxxxxxx>
> > Signed-off-by: Michal Vokáč <michal.vokac@xxxxxxxxx>
> > ---
> >  drivers/thermal/imx_thermal.c | 30 ++++++++++++++++++++++++++----
> >  1 file changed, 26 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
> > index 2c7473d86a59..df5658e21828 100644
> > --- a/drivers/thermal/imx_thermal.c
> > +++ b/drivers/thermal/imx_thermal.c
> > @@ -209,6 +209,8 @@ struct imx_thermal_data {
> >       struct clk *thermal_clk;
> >       const struct thermal_soc_data *socdata;
> >       const char *temp_grade;
> > +     struct mutex sensor_lock;
> > +     bool sensor_on;
> >  };
> >
> >  static void imx_set_panic_temp(struct imx_thermal_data *data,
> > @@ -252,11 +254,12 @@ 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;
> > +     bool wait;
> >       u32 val;
> >
> > -     run_measurement = !data->irq_enabled;
> > -     if (!run_measurement) {
> > +     mutex_lock(&data->sensor_lock);
> > +
> > +     if (data->sensor_on) {
> >               /* Check if a measurement is currently in progress */
> >               regmap_read(map, soc_data->temp_data, &val);
> >               wait = !(val & soc_data->temp_valid_mask);
> > @@ -283,13 +286,15 @@ static int imx_get_temp(struct thermal_zone_device *tz, int *temp)
> >
> >       regmap_read(map, soc_data->temp_data, &val);
> >
> > -     if (run_measurement) {
> > +     if (!data->sensor_on) {
> >               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);
> >       }
> >
> > +     mutex_unlock(&data->sensor_lock);
> > +
> >       if ((val & soc_data->temp_valid_mask) == 0) {
> >               dev_dbg(&tz->device, "temp measurement never finished\n");
> >               return -EAGAIN;
> > @@ -339,20 +344,26 @@ static int imx_change_mode(struct thermal_zone_device *tz,
> >       const struct thermal_soc_data *soc_data = data->socdata;
> >
> >       if (mode == THERMAL_DEVICE_ENABLED) {
> > +             mutex_lock(&data->sensor_lock);
> >               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);
> > +             data->sensor_on = true;
> > +             mutex_unlock(&data->sensor_lock);
> >
> >               if (!data->irq_enabled) {
> >                       data->irq_enabled = true;
> >                       enable_irq(data->irq);
> >               }
> >       } else {
> > +             mutex_lock(&data->sensor_lock);
> >               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);
> > +             data->sensor_on = false;
> > +             mutex_unlock(&data->sensor_lock);
> >
> >               if (data->irq_enabled) {
> >                       disable_irq(data->irq);
> > @@ -728,6 +739,8 @@ static int imx_thermal_probe(struct platform_device *pdev)
> >       }
> >
> >       /* Make sure sensor is in known good state for measurements */
> > +     mutex_init(&data->sensor_lock);
> > +     mutex_lock(&data->sensor_lock);
> >       regmap_write(map, data->socdata->sensor_ctrl + REG_CLR,
> >                    data->socdata->power_down_mask);
> >       regmap_write(map, data->socdata->sensor_ctrl + REG_CLR,
> > @@ -739,6 +752,8 @@ static int imx_thermal_probe(struct platform_device *pdev)
> >                       IMX6_MISC0_REFTOP_SELBIASOFF);
> >       regmap_write(map, data->socdata->sensor_ctrl + REG_SET,
> >                    data->socdata->power_down_mask);
> > +     data->sensor_on = false;
> > +     mutex_unlock(&data->sensor_lock);
> >
> >       ret = imx_thermal_register_legacy_cooling(data);
> >       if (ret)
> > @@ -796,10 +811,13 @@ static int imx_thermal_probe(struct platform_device *pdev)
> >       if (data->socdata->version == TEMPMON_IMX6SX)
> >               imx_set_panic_temp(data, data->temp_critical);
> >
> > +     mutex_lock(&data->sensor_lock);
> >       regmap_write(map, data->socdata->sensor_ctrl + REG_CLR,
> >                    data->socdata->power_down_mask);
> >       regmap_write(map, data->socdata->sensor_ctrl + REG_SET,
> >                    data->socdata->measure_temp_mask);
> > +     data->sensor_on = true;
> > +     mutex_unlock(&data->sensor_lock);
> >
> >       data->irq_enabled = true;
> >       ret = thermal_zone_device_enable(data->tz);
> > @@ -832,8 +850,12 @@ static int imx_thermal_remove(struct platform_device *pdev)
> >       struct regmap *map = data->tempmon;
> >
> >       /* Disable measurements */
> > +     mutex_lock(&data->sensor_lock);
> >       regmap_write(map, data->socdata->sensor_ctrl + REG_SET,
> >                    data->socdata->power_down_mask);
> > +     data->sensor_on = false;
> > +     mutex_unlock(&data->sensor_lock);
> > +
> >       if (!IS_ERR(data->thermal_clk))
> >               clk_disable_unprepare(data->thermal_clk);
> >
> > --
> > 2.25.1
> >