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From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Thu, 22 Feb 2024 17:13:42 +0100
Message-ID: <CAJZ5v0j6LWGnUfB6fbgHTXFOJ=n857ZSxqbd3u-5_FAVnbhXoQ@mail.gmail.com>
Subject: Re: [PATCH v2 2/9] thermal: core: Add flags to struct thermal_trip
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>, Linux PM <linux-pm@vger.kernel.org>, 
	Lukasz Luba <lukasz.luba@arm.com>, LKML <linux-kernel@vger.kernel.org>, 
	Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>, 
	Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>, Zhang Rui <rui.zhang@intel.com>, 
	netdev@vger.kernel.org, Ido Schimmel <idosch@nvidia.com>, Petr Machata <petrm@nvidia.com>, 
	Miri Korenblit <miriam.rachel.korenblit@intel.com>, linux-wireless@vger.kernel.org, 
	Shawn Guo <shawnguo@kernel.org>, Sascha Hauer <s.hauer@pengutronix.de>, 
	Pengutronix Kernel Team <kernel@pengutronix.de>, 
	Manaf Meethalavalappu Pallikunhi <quic_manafm@quicinc.com>
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On Thu, Feb 22, 2024 at 4:51=E2=80=AFPM Rafael J. Wysocki <rafael@kernel.or=
g> wrote:
>
> On Thu, Feb 22, 2024 at 3:36=E2=80=AFPM Daniel Lezcano
> <daniel.lezcano@linaro.org> wrote:
> >
> > On 12/02/2024 19:31, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > >
> > > In order to allow thermal zone creators to specify the writability of
> > > trip point temperature and hysteresis on a per-trip basis, add a flag=
s
> > > field to struct thermal_trip and define flags to represent the desire=
d
> > > trip properties.
> > >
> > > Also make thermal_zone_device_register_with_trips() set the
> > > THERMAL_TRIP_FLAG_RW_TEMP flag for all trips covered by the writable
> > > trips mask passed to it and modify the thermal sysfs code to look at
> > > the trip flags instead of using the writable trips mask directly or
> > > checking the presence of the .set_trip_hyst() zone callback.
> > >
> > > Additionally, make trip_point_temp_store() and trip_point_hyst_store(=
)
> > > fail with an error code if the trip passed to one of them has
> > > THERMAL_TRIP_FLAG_RW_TEMP or THERMAL_TRIP_FLAG_RW_HYST,
> > > respectively, clear in its flags.
> > >
> > > No intentional functional impact.
> > >
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > ---
> > >
> > > v1 -> v2:
> > >     * Rename trip flags (Stanislaw).
> > >
> > > ---
> > >   drivers/thermal/thermal_core.c  |   12 +++++++++++-
> > >   drivers/thermal/thermal_core.h  |    2 +-
> > >   drivers/thermal/thermal_sysfs.c |   28 +++++++++++++++++++---------
> > >   include/linux/thermal.h         |    7 +++++++
> > >   4 files changed, 38 insertions(+), 11 deletions(-)
> > >
> > > Index: linux-pm/include/linux/thermal.h
> > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> > > --- linux-pm.orig/include/linux/thermal.h
> > > +++ linux-pm/include/linux/thermal.h
> > > @@ -64,15 +64,23 @@ enum thermal_notify_event {
> > >    * @threshold: trip crossing notification threshold miliCelsius
> > >    * @type: trip point type
> > >    * @priv: pointer to driver data associated with this trip
> > > + * @flags: flags representing binary properties of the trip
> > >    */
> > >   struct thermal_trip {
> > >       int temperature;
> > >       int hysteresis;
> > >       int threshold;
> > >       enum thermal_trip_type type;
> > > +     u8 flags;
> > >       void *priv;
> > >   };
> > >
> > > +#define THERMAL_TRIP_FLAG_RW_TEMP    BIT(0)
> > > +#define THERMAL_TRIP_FLAG_RW_HYST    BIT(1)
> > > +
> > > +#define THERMAL_TRIP_FLAG_MASK_RW    (THERMAL_TRIP_FLAG_RW_TEMP | \
> > > +                                      THERMAL_TRIP_FLAG_RW_HYST)
> >
> > What about THERMAL_TRIP_FLAG_RW instead ?
>
> Fine with me.
>
> > >   struct thermal_zone_device_ops {
> > >       int (*bind) (struct thermal_zone_device *,
> > >                    struct thermal_cooling_device *);
> > > Index: linux-pm/drivers/thermal/thermal_core.c
> > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> > > --- linux-pm.orig/drivers/thermal/thermal_core.c
> > > +++ linux-pm/drivers/thermal/thermal_core.c
> > > @@ -1356,13 +1356,23 @@ thermal_zone_device_register_with_trips(
> > >       tz->devdata =3D devdata;
> > >       tz->trips =3D trips;
> > >       tz->num_trips =3D num_trips;
> > > +     if (num_trips > 0) {
> >
> > Is this check really necessary?
>
> No, it isn't.
>
> > for_each_trip() should exit immediately if there is no trip points.
>
> Right.
>
> > > +             struct thermal_trip *trip;
> > > +
> > > +             for_each_trip(tz, trip) {
> > > +                     if (mask & 1)
> > > +                             trip->flags |=3D THERMAL_TRIP_FLAG_RW_T=
EMP;
> > > +
> > > +                     mask >>=3D 1;
> > > +             }
> > > +     }
> > >
> > >       thermal_set_delay_jiffies(&tz->passive_delay_jiffies, passive_d=
elay);
> > >       thermal_set_delay_jiffies(&tz->polling_delay_jiffies, polling_d=
elay);
> > >
> > >       /* sys I/F */
> > >       /* Add nodes that are always present via .groups */
> > > -     result =3D thermal_zone_create_device_groups(tz, mask);
> > > +     result =3D thermal_zone_create_device_groups(tz);
> > >       if (result)
> > >               goto remove_id;
> > >
> > > Index: linux-pm/drivers/thermal/thermal_core.h
> > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> > > --- linux-pm.orig/drivers/thermal/thermal_core.h
> > > +++ linux-pm/drivers/thermal/thermal_core.h
> > > @@ -131,7 +131,7 @@ void thermal_zone_trip_updated(struct th
> > >   int __thermal_zone_get_temp(struct thermal_zone_device *tz, int *te=
mp);
> > >
> > >   /* sysfs I/F */
> > > -int thermal_zone_create_device_groups(struct thermal_zone_device *, =
int);
> > > +int thermal_zone_create_device_groups(struct thermal_zone_device *tz=
);
> > >   void thermal_zone_destroy_device_groups(struct thermal_zone_device =
*);
> > >   void thermal_cooling_device_setup_sysfs(struct thermal_cooling_devi=
ce *);
> > >   void thermal_cooling_device_destroy_sysfs(struct thermal_cooling_de=
vice *cdev);
> > > Index: linux-pm/drivers/thermal/thermal_sysfs.c
> > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> > > --- linux-pm.orig/drivers/thermal/thermal_sysfs.c
> > > +++ linux-pm/drivers/thermal/thermal_sysfs.c
> > > @@ -122,6 +122,11 @@ trip_point_temp_store(struct device *dev
> > >
> > >       trip =3D &tz->trips[trip_id];
> > >
> > > +     if (!(trip->flags & THERMAL_TRIP_FLAG_RW_TEMP)) {
> > > +             ret =3D -EPERM;
> > > +             goto unlock;
> > > +     }
> >
> > Does it really happen?
> >
> > If the sysfs file is created with the right permission regarding the
> > trip->flags then this condition can never be true.
>
> But the permissions can be changed after the file has been created, can't=
 they?

Even so, the .store() callback will not be set then anyway.

I'll send an update of this patch.