Re: [PATCH] thermal: gov_power_allocator: Allow binding without cooling devices

[Lukasz Luba]

Hi Rafael,

On 3/27/24 15:25, Rafael J. Wysocki wrote:
> On Thu, Mar 21, 2024 at 3:44 PM Nikita Travkin <nikita@xxxxxxx> wrote:
> > Commit e83747c2f8e3 ("thermal: gov_power_allocator: Set up trip points earlier")
> > added a check that would fail binding the governer if there is no
> > cooling devices bound to the thermal zone. Unfortunately this causes
> > issues in cases when the TZ is bound to the governer before the cooling
> > devices are attached to it. (I.e. when the tz is registered using
> > thermal_zone_device_register_with_trips().)
> >
> > Additionally, the documentation across gov_power_allocator suggests it's
> > intended to allow it to be bound to thermal zones without cooling
> > devices (and thus without passive/active trip points), however the same
> > change added a check for the trip point to be present, causing those TZ
> > to fail probing.
> >
> > Those changes cause all thermal zones to fail on some devices (such as
> > sc7180-acer-aspire1) and prevent the kernel from controlling the cpu/gpu
> > frequency based on the temperature, as well as losing all the other
> > "informational" thermal zones if power_allocator is set as default.
> >
> > This commit partially reverts the referenced one by dropping the trip
> > point check and by allowing the TZ to probe even if no actor buffer was
> > allocated to allow those TZ to probe again.
> >
> > Fixes: e83747c2f8e3 ("thermal: gov_power_allocator: Set up trip points earlier")
> > Signed-off-by: Nikita Travkin <nikita@xxxxxxx>
> > ---
> > I've noticed that all thermal zones fail probing with -EINVAL on my
> > sc7180 based Acer Aspire 1 since 6.8. This commit allows me to bring
> > them back.
>
> Łukasz, any comments?

Let me check this today.

> > ---
> >   drivers/thermal/gov_power_allocator.c | 14 +++++---------
> >   1 file changed, 5 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
> > index 1b17dc4c219c..4f2d7f3b7508 100644
> > --- a/drivers/thermal/gov_power_allocator.c
> > +++ b/drivers/thermal/gov_power_allocator.c
> > @@ -679,11 +679,6 @@ static int power_allocator_bind(struct thermal_zone_device *tz)
> >                  return -ENOMEM;
> >
> >          get_governor_trips(tz, params);
> > -       if (!params->trip_max) {
> > -               dev_warn(&tz->device, "power_allocator: missing trip_max\n");
> > -               kfree(params);
> > -               return -EINVAL;
> > -       }
> >
> >          ret = check_power_actors(tz, params);
> >          if (ret < 0) {
> > @@ -693,7 +688,7 @@ static int power_allocator_bind(struct thermal_zone_device *tz)
> >          }
> >
> >          ret = allocate_actors_buffer(params, ret);
> > -       if (ret) {
> > +       if (ret && ret != -EINVAL) {
> >                  dev_warn(&tz->device, "power_allocator: allocation failed\n");
> >                  kfree(params);
> >                  return ret;
> > @@ -714,9 +709,10 @@ static int power_allocator_bind(struct thermal_zone_device *tz)
> >          else
> >                  params->sustainable_power = tz->tzp->sustainable_power;
> >
> > -       estimate_pid_constants(tz, tz->tzp->sustainable_power,
> > -                              params->trip_switch_on,
> > -                              params->trip_max->temperature);
> > +       if (params->trip_max)
> > +               estimate_pid_constants(tz, tz->tzp->sustainable_power,
> > +                                      params->trip_switch_on,
> > +                                      params->trip_max->temperature);
> >
> >          reset_pid_controller(params);
> >
> >
> > ---
> > base-commit: e7528c088874326d3060a46f572252be43755a86
> > change-id: 20240321-gpa-no-cooling-devs-c79ee3288325
> >
> > Best regards,
> > --
> > Nikita Travkin <nikita@xxxxxxx>