On 12/21/23 07:28, Xuewen Yan wrote:
On Wed, Dec 20, 2023 at 7:02 PM Lukasz Luba <lukasz.luba@xxxxxxx> wrote:There are device drivers which can modify voltage values for OPPs. It could be due to the chip binning and those drivers have specific chip knowledge about this. This adjustment can happen after Energy Model is registered, thus EM can have stale data about power. Introduce new API function which can be used by device driver which adjusted the voltage for OPPs. The implementation takes care about calculating needed internal details in the new EM table ('cost' field). It plugs in the new EM table to the framework so other subsystems would use the correct data. Signed-off-by: Lukasz Luba <lukasz.luba@xxxxxxx> --- drivers/opp/of.c | 69 ++++++++++++++++++++++++++++++++++++++++++ include/linux/pm_opp.h | 6 ++++ 2 files changed, 75 insertions(+) diff --git a/drivers/opp/of.c b/drivers/opp/of.c index 81fa27599d58..992434c0b711 100644 --- a/drivers/opp/of.c +++ b/drivers/opp/of.c @@ -1596,3 +1596,72 @@ int dev_pm_opp_of_register_em(struct device *dev, struct cpumask *cpus) return ret; } EXPORT_SYMBOL_GPL(dev_pm_opp_of_register_em); + +/** + * dev_pm_opp_of_update_em() - Update Energy Model with new power values + * @dev : Device for which an Energy Model has to be registered + * + * This uses the "dynamic-power-coefficient" devicetree property to calculate + * power values for EM. It uses the new adjusted voltage values known for OPPs + * which have changed after boot. + */ +int dev_pm_opp_of_update_em(struct device *dev) +{ + struct em_perf_table __rcu *runtime_table; + struct em_perf_state *table, *new_table; + struct em_perf_domain *pd; + int ret, table_size, i; + + 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); + return -EINVAL; + } + + runtime_table = em_allocate_table(pd); + if (!runtime_table) { + dev_warn(dev, "new EM allocation failed\n"); + return -ENOMEM; + } + + new_table = runtime_table->state; + + table = em_get_table(pd); + /* Initialize data based on older EM table */ + table_size = sizeof(struct em_perf_state) * pd->nr_perf_states; + memcpy(new_table, table, table_size); + + em_put_table(); + + /* Update power values which might change due to new voltage in OPPs */ + for (i = 0; i < pd->nr_perf_states; i++) { + unsigned long freq = new_table[i].frequency; + unsigned long power; + + ret = _get_power(dev, &power, &freq); + if (ret) + goto failed;Need we use the EM_SET_ACTIVE_POWER_CB(em_cb, _get_power) and call em_cb->active_power?
No, not in this case. It's not like registration of EM, when there is a need to also pass the callback function. As you can see this code operates locally and the call _get_power() just simply gets the power in straight way. Later the whole 'runtime_table' is passed to the EM framework to 'swap' the pointers under RCU. Thanks Xuewen for having a look at this!
