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

Lukasz Luba
2024-03-22T10:26:36Z

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@arm.com>
>> ---
>> 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