[PATCH v2] thermal: sysfs: Make trip hysteresis writable along with trip temperature

[PATCH v2] thermal: sysfs: Make trip hysteresis writable along with trip temperature

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Trip point temperature can be modified via sysfs if
CONFIG_THERMAL_WRITABLE_TRIPS is enabled and the thermal
zone creator requested that the given trip be writable
in the writable trips mask passed to the registration
function.

However, trip point hysteresis is treated differently - it is only
writable if the thermal zone has a .set_trip_hyst() operation defined
and neither CONFIG_THERMAL_WRITABLE_TRIPS, nor the writable trips mask
supplied by the zone creator has any bearing on this.  That is
inconsistent and confusing, and it generally does not meet user
expectations.

For this reason, modify create_trip_attrs() to handle trip point
hysteresis in the same way as trip point temperature, so they both
are writable at the same time regardless of what trip point operations
are defined for the thermal zone.

Link: https://lore.kernel.org/linux-pm/20240106191502.29126-1-quic_manafm@quicinc.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v1 -> v2: Fix patch corruption (Daniel).

---
 drivers/thermal/thermal_sysfs.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-pm/drivers/thermal/thermal_sysfs.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_sysfs.c
+++ linux-pm/drivers/thermal/thermal_sysfs.c
@@ -474,7 +474,8 @@ static int create_trip_attrs(struct ther
 					tz->trip_hyst_attrs[indx].name;
 		tz->trip_hyst_attrs[indx].attr.attr.mode = S_IRUGO;
 		tz->trip_hyst_attrs[indx].attr.show = trip_point_hyst_show;
-		if (tz->ops->set_trip_hyst) {
+		if (IS_ENABLED(CONFIG_THERMAL_WRITABLE_TRIPS) &&
+		    mask & (1 << indx)) {
 			tz->trip_hyst_attrs[indx].attr.attr.mode |= S_IWUSR;
 			tz->trip_hyst_attrs[indx].attr.store =
 					trip_point_hyst_store;

Re: [PATCH v2] thermal: sysfs: Make trip hysteresis writable along with trip temperature

[Daniel Lezcano]

On 31/01/2024 19:44, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> Trip point temperature can be modified via sysfs if
> CONFIG_THERMAL_WRITABLE_TRIPS is enabled and the thermal
> zone creator requested that the given trip be writable
> in the writable trips mask passed to the registration
> function.
> 
> However, trip point hysteresis is treated differently - it is only
> writable if the thermal zone has a .set_trip_hyst() operation defined
> and neither CONFIG_THERMAL_WRITABLE_TRIPS, nor the writable trips mask
> supplied by the zone creator has any bearing on this.  That is
> inconsistent and confusing, and it generally does not meet user
> expectations.
> 
> For this reason, modify create_trip_attrs() to handle trip point
> hysteresis in the same way as trip point temperature, so they both
> are writable at the same time regardless of what trip point operations
> are defined for the thermal zone.
> 
> Link: https://lore.kernel.org/linux-pm/20240106191502.29126-1-quic_manafm@quicinc.com
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>

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Re: [PATCH v2] thermal: sysfs: Make trip hysteresis writable along with trip temperature

[Rafael J. Wysocki]

On Thu, Feb 8, 2024 at 3:42 PM Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
>
> On 31/01/2024 19:44, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > Trip point temperature can be modified via sysfs if
> > CONFIG_THERMAL_WRITABLE_TRIPS is enabled and the thermal
> > zone creator requested that the given trip be writable
> > in the writable trips mask passed to the registration
> > function.
> >
> > However, trip point hysteresis is treated differently - it is only
> > writable if the thermal zone has a .set_trip_hyst() operation defined
> > and neither CONFIG_THERMAL_WRITABLE_TRIPS, nor the writable trips mask
> > supplied by the zone creator has any bearing on this.  That is
> > inconsistent and confusing, and it generally does not meet user
> > expectations.
> >
> > For this reason, modify create_trip_attrs() to handle trip point
> > hysteresis in the same way as trip point temperature, so they both
> > are writable at the same time regardless of what trip point operations
> > are defined for the thermal zone.
> >
> > Link: https://lore.kernel.org/linux-pm/20240106191502.29126-1-quic_manafm@quicinc.com
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
>
> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Thanks, but I need to withdraw this one, because there are drivers
that actively don't want their trip points' hysteresis to be adjusted
via sysfs, so I'm now working on a patch series that will tackle this
in a more systematic way.