Hi,

On Tue, Jul 31, 2018 at 11:59 AM, Matthias Kaehlcke [off-list ref] wrote:

There are three thermal stages defined in the PMIC:

stage 1: warning
stage 2: system should shut down
stage 3: emergency shut down

By default the PMIC assumes that the OS isn't doing anything and thus
at stage 2 it does a partial PMIC shutdown and at stage 3 it kills
all power. When switching between thermal stages the PMIC generates an
interrupt which is handled by the driver. The partial PMIC shutdown at
stage 2 can be disabled by software, which allows the OS to initiate a
shutdown at stage 2 with a thermal zone configured accordingly.

If a critical trip point is configured in the thermal zone the driver
adjusts the stage 1-3 temperature thresholds to (closely) match the
critical temperature with a stage 2 threshold (125/130/135/140 °C).
If a suitable match is found the partial shutdown at stage 2 is
disabled. If for some reason the system doesn't shutdown at stage 2
the emergency shutdown at stage 3 kicks in.

The partial shutdown at stage 2 remains enabled in these cases:
- no critical trip point defined
- the temperature of the critical trip point is < 125°C
- the temperature of the critical trip point is > 140°C and no
  ADC channel is configured (thus the OS is not notified when the critical
  temperature is reached)

Suggested-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
Changes in v6:
- fixed condition to check if ADC is configured in
  qpnp_tm_update_critical_trip_temp()
- changed °C in logs to C
- removed needless evaluation of qpnp_tm_write() return value in
  qpnp_tm_update_critical_trip_temp()
- move assignment of chip->initialized to true to qpnp_tm_init(),
  where the lock is held
- call thermal_zone_device_update() after initialization is
  completed
- split some #define + comment in two lines to avoid exceeding
  chars per line limit
- removed extra closing parenthesis in qpnp_tm_get_temp()
- remove unnecessary parentheses around conditions in
  qpnp_tm_update_critical_trip_temp() and qpnp_tm_get_critical_trip_temp()
- fixed indentation of call devm_thermal_zone_of_sensor_register() call
  in qpnp_tm_probe()

Changes in v5:
- patch added to the series
---
 drivers/thermal/qcom-spmi-temp-alarm.c | 158 ++++++++++++++++++++++---
 1 file changed, 140 insertions(+), 18 deletions(-)

I won't claim to have spent too much time in the thermal framework,
but from what I can tell everything looks supergreat now.  FWIW:

Reviewed-by: Douglas Anderson <dianders@chromium.org>

One minor comment I'd have is that I personally would have ordered
this in the series before the patch ("dt-bindings: thermal:
qcom-spmi-temp-alarm: Improve thermal zone in example") just because
that patch only really makes sense after this one lands.  ...but I
don't think it's terribly important.


-Doug