Re: [PATCH 3/4] PM: EM: Add em_dev_update_chip_binning()

[Lukasz Luba]

Hi Christian,

On 3/14/24 14:32, Christian Loehle wrote:
> On 14/03/2024 14:04, Lukasz Luba wrote:
> > Add a function which allows to modify easily the EM after the new voltage
> > information is available. The device drivers for the chip can adjust
> > the voltage values after setup. The voltage for the same frequency in OPP
> > can be different due to chip binning. The voltage impacts the power usage
> > and the EM power values can be updated to reflect that.
> >
> > Signed-off-by: Lukasz Luba <lukasz.luba@xxxxxxx>
> > ---
> >   include/linux/energy_model.h |  5 ++++
> >   kernel/power/energy_model.c  | 51 ++++++++++++++++++++++++++++++++++++
> >   2 files changed, 56 insertions(+)
> >
> > diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
> > index 770755df852f1..d30d67c2f07cf 100644
> > --- a/include/linux/energy_model.h
> > +++ b/include/linux/energy_model.h
> > @@ -172,6 +172,7 @@ struct em_perf_table __rcu *em_table_alloc(struct em_perf_domain *pd);
> >   void em_table_free(struct em_perf_table __rcu *table);
> >   int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
> >   			 int nr_states);
> > +int em_dev_update_chip_binning(struct device *dev);
> >   
> >   /**
> >    * em_pd_get_efficient_state() - Get an efficient performance state from the EM
> > @@ -387,6 +388,10 @@ int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
> >   {
> >   	return -EINVAL;
> >   }
> > +static inline int em_dev_update_chip_binning(struct device *dev)
> > +{
> > +	return -EINVAL;
> > +}
> >   #endif
> >   
> >   #endif
> > diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
> > index 6960dd7393b2d..1494a909844a4 100644
> > --- a/kernel/power/energy_model.c
> > +++ b/kernel/power/energy_model.c
> > @@ -808,3 +808,54 @@ static void em_update_workfn(struct work_struct *work)
> >   {
> >   	em_check_capacity_update();
> >   }
> > +
> > +/**
> > + * em_dev_update_chip_binning() - Update Energy Model with new values after
> > + *			the new voltage information is present in the OPPs.
> > + * @dev		: Device for which the Energy Model has to be updated.
> > + *
> > + * This function allows to update easily the EM with new values available in
> > + * the OPP framework and DT. It can be used after the chip has been properly
> > + * verified by device drivers and the voltages adjusted for the 'chip binning'.
> > + * It uses the "dynamic-power-coefficient" DT property to calculate the power
> > + * values for EM. For power calculation it uses the new adjusted voltage
> > + * values known for OPPs, which might be changed after boot.
> > + */
> > +int em_dev_update_chip_binning(struct device *dev)
> > +{
> > +	struct em_perf_table __rcu *em_table;
> > +	struct em_perf_domain *pd;
> > +	int i, ret;
> > +
> > +	if (IS_ERR_OR_NULL(dev))
> > +		return -EINVAL;
> > +
> > +	pd = em_pd_get(dev);
> > +	if (!pd) {
> > +		dev_warn(dev, "Couldn't find Energy Model %d\n", ret);
>
> ret is uninitialized at this point, I guess just
> +		dev_warn(dev, "Couldn't find Energy Model\n");
> already contains everything relevant.

Good catch, thanks! Yes, I agree it contains enough. I'm going
to send v2 with this.

Regards,
Lukasz