Re: [PATCH V3 3/6] thermal: Register hwmon in thermal_zone_of_sensor_register_param()

[Eduardo Valentin <edubezval@gmail.com>]

On Mon, Jan 28, 2019 at 01:10:11PM +0100, Marek Vasut wrote:
> On 1/15/19 1:35 AM, Marek Vasut wrote:
> > On 12/22/18 3:19 AM, Marek Vasut wrote:
> >> On 12/18/2018 10:44 PM, Eduardo Valentin wrote:
> >>> On Mon, Dec 17, 2018 at 04:56:41PM +0100, marek.vasut@gmail.com wrote:
> >>>> From: Marek Vasut <marek.vasut@gmail.com>
> >>>>
> >>>> Register hwmon sysfs interface in thermal_zone_of_sensor_register_param()
> >>>> in case thermal_zone_params->no_hwmon is set to false. This behavior is
> >>>> the same as thermal_zone_device_register().
> >>>>
> >>>> From: Marek Vasut <marek.vasut+renesas@gmail.com>
> >>>> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> >>>> Cc: Eduardo Valentin <edubezval@gmail.com>
> >>>> Cc: Wolfram Sang <wsa+renesas@sang-engineering.com>
> >>>> Cc: Zhang Rui <rui.zhang@intel.com>
> >>>> Cc: linux-renesas-soc@vger.kernel.org
> >>>> To: linux-pm@vger.kernel.org
> >>>> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
> >>>> ---
> >>>> V2: No change
> >>>> V3: - Work around the From line and SoB line checkpatch warning
> >>>>     - Reorder the SoB line at the end
> >>>> ---
> >>>>  drivers/thermal/of-thermal.c | 12 +++++++++++-
> >>>>  1 file changed, 11 insertions(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
> >>>> index e1a303a5698c..5ccff7b678de 100644
> >>>> --- a/drivers/thermal/of-thermal.c
> >>>> +++ b/drivers/thermal/of-thermal.c
> >>>> @@ -15,6 +15,7 @@
> >>>>  #include <linux/string.h>
> >>>>  
> >>>>  #include "thermal_core.h"
> >>>> +#include "thermal_hwmon.h"
> >>>>  
> >>>>  /***   Private data structures to represent thermal device tree data ***/
> >>>>  
> >>>> @@ -521,8 +522,15 @@ thermal_zone_of_sensor_register_params(struct device *dev, int sensor_id,
> >>>>  		if (sensor_specs.np == sensor_np && id == sensor_id) {
> >>>>  			tzd = thermal_zone_of_add_sensor(child, sensor_np,
> >>>>  							 data, ops);
> >>>> -			if (!IS_ERR(tzd))
> >>>> +			if (!IS_ERR(tzd)) {
> >>>> +				tzd->tzp = tzp;
> >>>
> >>> So, here you will overwrite what was done in of_parse_thermal_zones().
> >>> That means, after this point, property like sustainable power, slope and
> >>> offset are gone.
> >>
> >> Hmmmmm, that was rather inobvious, indeed.
> >>
> >> Do you have some suggestion how to pass in the no_hwmon = false then ?
> >> Since tzp->no_hwmon is set to true in of_parse_thermal_zones(), the
> >> three drivers (stm32, rcar, rcar_gen3) seem to hack around it. I'd like
> >> to clean that up.
> > 

Yeah, that is an issue.

> > Bump ?
> 
> Bump again, any suggestions ?

Yeah, a couple of ideas have been proposed for this issue.

First most tempting one is to have a DT property per thermal zone.
Making it linux specific, something prefixed by linux,<property>. I
recall Amit Kutcheria trying something similar to this, but dont
remember where that went. Frankly, this is a Linux thing, I am not
convinced DT is really the right place to fix this.

Another hack that could be written is a module parameter for of-thermal
that would reflect the no_hwmon value, globally. The down side here is
you have to make sure all drivers match that no_hwmon value, right?
> 
> -- 
> Best regards,
> Marek Vasut