Date:   Mon, 25 Jul 2022 01:28:26 +0200
From:   Niklas Söderlund 
        <niklas.soderlund@...natech.se>
To:     Daniel Lezcano <daniel.lezcano@...exp.org>
Cc:     daniel.lezcano@...aro.org, rafael@...nel.org, rui.zhang@...el.com,
        khilman@...libre.com, abailon@...libre.com, amitk@...nel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        "open list:RENESAS R-CAR THERMAL DRIVERS" 
        <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v1 17/33] thermal/drivers/rcar: Switch to new of API

Hi (again) Daniel,

I figured it out, the thermal zone is disabled after this change. For 
both rcar sensors with the new API thermal_zone_device_enable() is never 
called.

In the old API the zone is enabled in the call chain of 
devm_thermal_zone_of_sensor_register(). While after this change the zone 
is not enabled by the core when calling thermal_zone_device_enable().

If I add a call to thermal_zone_device_enable() together with the new 
API everything works as before. But I'm not sure if the correct solution 
is to add a call to thermal_zone_device_enable() in the sensor drivers 
or in the call chain of the new API?

On 2022-07-25 00:39:10 +0200, Niklas Söderlund wrote:
> Hi Daniel,
> 
> I tested your branch, unfortunately with the same result for 
> rcar_gen3_thermal. Manipulation of emul_temp file do not trigger 
> actions.
> 
> If I on-top of your branch revert:
> 
>     409ca214f4c6bd5b ("thermal/of: Remove old OF code")
>     7b43f76d3428227e ("thermal/drivers/rcar: Switch to new of API")
> 
> I'm able to 'restore' the behavior where I can change the cooling state 
> and trigger the critical trip point using emul_temp to shutdown the 
> board.
> 
> As the change in question also effects the rcar_thermal sensor I gave 
> that a try too. It have no cooling on this system I have so my only 
> test-case is to write a temperature above the critical trip point to 
> emul_temp as see if that shutdown the system.  And just as with 
> rcar_gen3_thermal with your series nothing happens while with the two 
> commits outline above reverted the system shuts down.
> 
>     echo 110000 > /sys/devices/virtual/thermal/thermal_zone0/emul_temp
> 
> If it's any help writing to emul_temp have some effect as the emulated 
> temperature is read back from the temp sysfs while. For rcar_thermal 
> where the critical trip point is 95 degrees,
> 
>     * With this series
>     # grep . /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_*
>     /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_hyst:0
>     /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_temp:95000
>     /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_type:critical
>     # cat /sys/devices/virtual/thermal/thermal_zone0/temp
>     35000
>     # echo 50000 > /sys/devices/virtual/thermal/thermal_zone0/emul_temp
>     # cat /sys/devices/virtual/thermal/thermal_zone0/temp
>     50000
>     # echo 110000 > /sys/devices/virtual/thermal/thermal_zone0/emul_temp
>     # cat /sys/devices/virtual/thermal/thermal_zone0/temp
>     110000
>     *** system alive ***
> 
>     * With this series and the two patches reverted or plain v5.19-rc4
>     # grep .  /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_* 
>     /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_hyst:0
>     /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_temp:95000
>     /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_type:critical
>     # cat /sys/devices/virtual/thermal/thermal_zone0/temp
>     35000
>     # echo 50000 > /sys/devices/virtual/thermal/thermal_zone0/emul_temp
>     # cat /sys/devices/virtual/thermal/thermal_zone0/temp
>     50000
>     # echo 110000 > /sys/devices/virtual/thermal/thermal_zone0/emul_temp
>     [  121.380054] thermal thermal_zone0: cpu-thermal: critical temperature reached, shutting down
>     [  121.388482] reboot: HARDWARE PROTECTION shutdown (Temperature too high)
>     *** system shuts down ***
> 
> And to make it more problematic I don't think the lack of action is 
> limited to the emul_temp interface. With rcar_thermal I lowered the 
> critical trip point value to 45C and used the cpuburn application to 
> generate load and raise the temperature.
> 
> The result mirrors the findings above, with your branch the system do 
> not trigger the critical trip point. If I revert the two commits or run 
> plain v5.19-rc4, once the temperature reaches 45C the critical trip 
> point kicks in and shuts down the system.
> 
> I hope this helps, I'm sorry I can't find the real issue diging in the 
> core changes. I'm happy to help trying to find the root cause for this 
> and I think the idea behind the new API is good.
> 
> On 2022-07-24 23:11:47 +0200, Daniel Lezcano wrote:
> > 
> > Hi Niklas,
> > 
> > I give another try but failed to reproduce the issue. Perhaps my board has a
> > path different from yours.
> > 
> > Thanks for proposing to test the series. I've uploaded the branch here:
> > 
> > https://github.com/dlezcano/linux-thermal
> > 
> > 
> > On 24/07/2022 21:00, Niklas Söderlund wrote:
> > > Hi Daniel,
> > > 
> > > On 2022-07-24 20:27:54 +0200, Daniel Lezcano wrote:
> > > > Hi Niklas,
> > > > 
> > > > I tried to reproduce the issue but without success.
> > > > 
> > > > What sensor are you using ?
> > > I was using rcar_gen3_thermal.
> > > 
> > > I did my tests starting on v5.19-rc7 and then picked '[PATCH v5 00/12]
> > > thermal OF rework' from [1] and finally applied this full series on-top
> > > of that. If you have a branch or some specific test you wish me to try
> > > I'm happy to so.
> > > 
> > > 1. https://lore.kernel.org/lkml/20220710123512.1714714-1-daniel.lezcano@linexp.org/
> > > 
> > > > 
> > > > On 19/07/2022 11:10, Niklas Söderlund wrote:
> > > > > Hi Daniel,
> > > > > 
> > > > > Thanks for your work.
> > > > > 
> > > > > On 2022-07-10 23:24:07 +0200, Daniel Lezcano wrote:
> > > > > > The thermal OF code has a new API allowing to migrate the OF
> > > > > > initialization to a simpler approach.
> > > > > > 
> > > > > > Use this new API.
> > > > > I tested this together with the series it depends on and while
> > > > > temperature monitoring seems to work fine it breaks the emul_temp
> > > > > interface (/sys/class/thermal/thermal_zone2/emul_temp).
> > > > > 
> > > > > Before this change I can write a temperature to this file and have it
> > > > > trigger actions, in my test-case changing the cooling state, which I
> > > > > observe in /sys/class/thermal/cooling_device0/cur_state.
> > > > > 
> > > > > Likewise before this change I could trip the critical trip-point that
> > > > > would power off the board using the emul_temp interface, this too no
> > > > > longer works,
> > > > > 
> > > > >       echo 120000 > /sys/class/thermal/thermal_zone2/emul_temp
> > > > > 
> > > > > Is this an intention change of the new API?
> > > > 
> > > > 
> > > > 
> > 
> 
> -- 
> Kind Regards,
> Niklas Söderlund

-- 
Kind Regards,
Niklas Söderlund

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