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Wysocki" , Liam Girdwood , Rob Herring , linux-kernel@vger.kernel.org, Kyungmin Park , MyungJoo Ham , linux-mediatek@lists.infradead.org, Sibi Sankar , Matthias Brugger , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org On Thu, 2020-05-28 at 15:14 +0900, Chanwoo Choi wrote: > Hi Andrew-sh.Cheng, > > Thanks for your posting. I like this approach absolutely. > I think that it is necessary. When I developed the embedded product, > I needed this feature always. > > I add the comments on below. > > > And the following email is not valid. So, I dropped this email > from Cc list. > Saravana Kannan > > > On 5/20/20 12:43 PM, Andrew-sh.Cheng wrote: > > From: Saravana Kannan > > > > Many CPU architectures have caches that can scale independent of the > > CPUs. Frequency scaling of the caches is necessary to make sure that the > > cache is not a performance bottleneck that leads to poor performance and > > power. The same idea applies for RAM/DDR. > > > > To achieve this, this patch adds support for cpu based scaling to the > > passive governor. This is accomplished by taking the current frequency > > of each CPU frequency domain and then adjust the frequency of the cache > > (or any devfreq device) based on the frequency of the CPUs. It listens > > to CPU frequency transition notifiers to keep itself up to date on the > > current CPU frequency. > > > > To decide the frequency of the device, the governor does one of the > > following: > > * Derives the optimal devfreq device opp from required-opps property of > > the parent cpu opp_table. > > > > * Scales the device frequency in proportion to the CPU frequency. So, if > > the CPUs are running at their max frequency, the device runs at its > > max frequency. If the CPUs are running at their min frequency, the > > device runs at its min frequency. It is interpolated for frequencies > > in between. > > > > Andrew-sh.Cheng change > > dev_pm_opp_xlate_opp to dev_pm_opp_xlate_required_opp devfreq->max_freq > > to devfreq->user_min_freq_req.data.freq.qos->min_freq.target_value > > for kernel-5.7 > > > > Signed-off-by: Saravana Kannan > > [Sibi: Integrated cpu-freqmap governor into passive_governor] > > Signed-off-by: Sibi Sankar > > Signed-off-by: Andrew-sh.Cheng > > --- > > drivers/devfreq/Kconfig | 2 + > > drivers/devfreq/governor_passive.c | 278 ++++++++++++++++++++++++++++++++++--- > > include/linux/devfreq.h | 40 +++++- > > 3 files changed, 299 insertions(+), 21 deletions(-) > > > > diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig > > index 0b1df12e0f21..d9067950af6a 100644 > > --- a/drivers/devfreq/Kconfig > > +++ b/drivers/devfreq/Kconfig > > @@ -73,6 +73,8 @@ config DEVFREQ_GOV_PASSIVE > > device. This governor does not change the frequency by itself > > through sysfs entries. The passive governor recommends that > > devfreq device uses the OPP table to get the frequency/voltage. > > + Alternatively the governor can also be chosen to scale based on > > + the online CPUs current frequency. > > > > comment "DEVFREQ Drivers" > > > > diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c > > index 2d67d6c12dce..7dcda02a5bb7 100644 > > --- a/drivers/devfreq/governor_passive.c > > +++ b/drivers/devfreq/governor_passive.c > > @@ -8,11 +8,89 @@ > > */ > > > > #include > > +#include > > +#include > > +#include > > #include > > #include > > +#include > > #include "governor.h" > > > > -static int devfreq_passive_get_target_freq(struct devfreq *devfreq, > > +static unsigned int xlate_cpufreq_to_devfreq(struct devfreq_passive_data *data, > > Need to change 'unsigned int' to 'unsigned long' Get it. > . > > > + unsigned int cpu) > > +{ > > + unsigned int cpu_min, cpu_max, dev_min, dev_max, cpu_percent, max_state; > > Better to define them separately as following and then need to rename > the variable. Usually, use the 'min_freq' and 'max_freq' word for > the minimum/maximum frequency. > > unsigned int cpu_min_freq, cpu_max_freq, cpu_curr_freq, cpu_percent; > unsigned long dev_min_freq, dev_max_freq, dev_max_state, > > The devfreq used 'unsigned long'. The cpufreq used 'unsigned long' > and 'unsigned int'. You need to handle them properly. Get it. For cpu_freq, I separate it into "unsigned long cpu_curr_freq" and "unsigned int cpu_curr_freq_khz" > > > > + struct devfreq_cpu_state *cpu_state = data->cpu_state[cpu]; > > + struct devfreq *devfreq = (struct devfreq *)data->this; > > + unsigned long *freq_table = devfreq->profile->freq_table; > > In this function, use 'cpu' work for cpufreq and use 'dev' for devfreq. > So, I think 'dev_freq_table' is proper name instead of 'freq_table' > for the readability. > > freq_table -> dev_freq_table > > > + struct dev_pm_opp *opp = NULL, *cpu_opp = NULL; > > In the get_target_freq_with_devfreq(), use 'p_opp' indicating > the OPP of parent device. For the consistency, I think that > use 'p_opp' instead of 'cpu_opp'. > > > + unsigned long cpu_freq, freq; > > Define the 'cpu_freq' on above with cpu_min_freq/cpu_max_freq definition. > cpu_freq -> cpu_curr_freq. Get it. Will modify them for readability. > > > + > > + if (!cpu_state || cpu_state->first_cpu != cpu || > > + !cpu_state->opp_table || !devfreq->opp_table) > > + return 0; > > + > > + cpu_freq = cpu_state->freq * 1000; > > + cpu_opp = devfreq_recommended_opp(cpu_state->dev, &cpu_freq, 0); > > + if (IS_ERR(cpu_opp)) > > + return 0; > > + > > + opp = dev_pm_opp_xlate_required_opp(cpu_state->opp_table, > > + devfreq->opp_table, cpu_opp); > > + dev_pm_opp_put(cpu_opp); > > + > > + if (!IS_ERR(opp)) { > > + freq = dev_pm_opp_get_freq(opp); > > + dev_pm_opp_put(opp); > > Better to add the 'out' goto statement. > If you use 'goto out', you can reduce the one indentation > without 'else' statement. Get it. > > > > + } else { > > As I commented, when dev_pm_opp_xlate_required_opp() return successfully > , use 'goto out'. We can remove 'else' and then reduce the unneeded indentation. > > > > + /* Use Interpolation if required opps is not available */ > > + cpu_min = cpu_state->min_freq; > > + cpu_max = cpu_state->max_freq; > > + cpu_freq = cpu_state->freq; > > + > > + if (freq_table) { > > + /* Get minimum frequency according to sorting order */ > > + max_state = freq_table[devfreq->profile->max_state - 1]; > > + if (freq_table[0] < max_state) { > > + dev_min = freq_table[0]; > > + dev_max = max_state; > > + } else { > > + dev_min = max_state; > > + dev_max = freq_table[0]; > > + } > > + } else { > > + if (devfreq->user_max_freq_req.data.freq.qos->max_freq.target_value > > + <= devfreq->user_min_freq_req.data.freq.qos->min_freq.target_value) > > + return 0; > > + dev_min = > > + devfreq->user_min_freq_req.data.freq.qos->min_freq.target_value; > > + dev_max = > > + devfreq->user_max_freq_req.data.freq.qos->max_freq.target_value; > > I think it is not proper to access the variable of pm_qos structure directly. > Instead of direct access, you have to use the exported PM QoS function such as > - pm_qos_read_value(devfreq->dev.parent, DEV_PM_QOS_MIN_FREQUENCY); > - pm_qos_read_value(devfreq->dev.parent, DEV_PM_QOS_MAX_FREQUENCY); Get it. > > > + } > > + cpu_percent = ((cpu_freq - cpu_min) * 100) / cpu_max - cpu_min; > > + freq = dev_min + mult_frac(dev_max - dev_min, cpu_percent, 100); > > + } > > > I think that you better to add 'out' jump label as following: > > out: > > > + > > + return freq; > > +} > > + > > +static int get_target_freq_with_cpufreq(struct devfreq *devfreq, > > + unsigned long *freq) > > +{ > > + struct devfreq_passive_data *p_data = > > + (struct devfreq_passive_data *)devfreq->data; > > + unsigned int cpu, target_freq = 0; > > Need to define 'target_freq' with 'unsigned long' type. Get it. > > > + > > + for_each_online_cpu(cpu) > > + target_freq = max(target_freq, > > + xlate_cpufreq_to_devfreq(p_data, cpu)); > > + > > + *freq = target_freq; > > + > > + return 0; > > +} > > + > > +static int get_target_freq_with_devfreq(struct devfreq *devfreq, > > unsigned long *freq) > > { > > struct devfreq_passive_data *p_data > > @@ -23,16 +101,6 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq, > > int i, count, ret = 0; > > > > /* > > - * If the devfreq device with passive governor has the specific method > > - * to determine the next frequency, should use the get_target_freq() > > - * of struct devfreq_passive_data. > > - */ > > - if (p_data->get_target_freq) { > > - ret = p_data->get_target_freq(devfreq, freq); > > - goto out; > > - } > > - > > - /* > > * If the parent and passive devfreq device uses the OPP table, > > * get the next frequency by using the OPP table. > > */ > > @@ -102,6 +170,37 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq, > > return ret; > > } > > > > +static int devfreq_passive_get_target_freq(struct devfreq *devfreq, > > + unsigned long *freq) > > +{ > > + struct devfreq_passive_data *p_data = > > + (struct devfreq_passive_data *)devfreq->data; > > + int ret; > > + > > + /* > > + * If the devfreq device with passive governor has the specific method > > + * to determine the next frequency, should use the get_target_freq() > > + * of struct devfreq_passive_data. > > + */ > > + if (p_data->get_target_freq) > > + return p_data->get_target_freq(devfreq, freq); > > + > > + switch (p_data->parent_type) { > > + case DEVFREQ_PARENT_DEV: > > + ret = get_target_freq_with_devfreq(devfreq, freq); > > + break; > > + case CPUFREQ_PARENT_DEV: > > + ret = get_target_freq_with_cpufreq(devfreq, freq); > > + break; > > + default: > > + ret = -EINVAL; > > + dev_err(&devfreq->dev, "Invalid parent type\n"); > > + break; > > + } > > + > > + return ret; > > +} > > + > > static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq) > > { > > int ret; > > @@ -156,6 +255,140 @@ static int devfreq_passive_notifier_call(struct notifier_block *nb, > > return NOTIFY_DONE; > > } > > > > +static int cpufreq_passive_notifier_call(struct notifier_block *nb, > > + unsigned long event, void *ptr) > > +{ > > + struct devfreq_passive_data *data = > > + container_of(nb, struct devfreq_passive_data, nb); > > + struct devfreq *devfreq = (struct devfreq *)data->this; > > + struct devfreq_cpu_state *cpu_state; > > + struct cpufreq_freqs *freq = ptr; > > How about changing 'freq' to 'cpu_freqs'? > > In the drivers/cpufreq/cpufreq.c, use 'freqs' name indicating > the instance of 'struct cpufreq_freqs'. And in order to > identfy, how about adding 'cpu_' prefix for variable name? > > > + unsigned int current_freq; > > Need to define curr_freq with 'unsigned long' type > and better to use 'curr_freq' variable name. It is good to change current_freq to curr_freq, but why should it us 'unsigned long'? I think it is 'unsigned int'. > > > + int ret; > > + > > + if (event != CPUFREQ_POSTCHANGE || !freq || > > + !data->cpu_state[freq->policy->cpu]) > > + return 0; > > + > > + cpu_state = data->cpu_state[freq->policy->cpu]; > > + if (cpu_state->freq == freq->new) > > + return 0; > > + > > + /* Backup current freq and pre-update cpu state freq*/ > > + current_freq = cpu_state->freq; > > + cpu_state->freq = freq->new; > > + > > + mutex_lock(&devfreq->lock); > > + ret = update_devfreq(devfreq); > > + mutex_unlock(&devfreq->lock); > > + if (ret) { > > + cpu_state->freq = current_freq; > > + dev_err(&devfreq->dev, "Couldn't update the frequency.\n"); > > + return ret; > > + } > > + > > + return 0; > > +} > > + > > +static int cpufreq_passive_register(struct devfreq_passive_data **p_data) > > +{ > > + struct devfreq_passive_data *data = *p_data; > > + struct devfreq *devfreq = (struct devfreq *)data->this; > > + struct device *dev = devfreq->dev.parent; > > + struct opp_table *opp_table = NULL; > > + struct devfreq_cpu_state *state; > > For the readability, I thinkt 'cpu_state' is proper instead of 'state'. Get it. > > > + struct cpufreq_policy *policy; > > + struct device *cpu_dev; > > + unsigned int cpu; > > + int ret; > > + > > + get_online_cpus(); > > Add blank line. Get it. > > > + data->nb.notifier_call = cpufreq_passive_notifier_call; > > + ret = cpufreq_register_notifier(&data->nb, > > + CPUFREQ_TRANSITION_NOTIFIER); > > + if (ret) { > > + dev_err(dev, "Couldn't register cpufreq notifier.\n"); > > + data->nb.notifier_call = NULL; > > + goto out; > > + } > > + > > + /* Populate devfreq_cpu_state */ > > + for_each_online_cpu(cpu) { > > + if (data->cpu_state[cpu]) > > + continue; > > + > > + policy = cpufreq_cpu_get(cpu); > > cpufreq_cpu_get() might return 'NULL'. I think you need to handle > return value as following: > > if (!policy) { > ret = -EINVAL; > goto out; > } else if (PTR_ERR(policy) == -EPROBE_DEFER) { > goto out; > } else if (IS_ERR(policy) { > ret = PTR_ERR(policy); > dev_err(dev, "Couldn't get the cpufreq_poliy.\n"); > goto out; > } > > If cpufreq_cpu_get() return successfully, to do next. > It reduces the one indentaion. > > Get it. > > > + if (policy) { > > + state = kzalloc(sizeof(*state), GFP_KERNEL); > > + if (!state) { > > + ret = -ENOMEM; > > + goto out; > > + } > > + > > + cpu_dev = get_cpu_device(cpu); > > + if (!cpu_dev) { > > + dev_err(dev, "Couldn't get cpu device.\n"); > > + ret = -ENODEV; > > + goto out; > > + } > > + > > + opp_table = dev_pm_opp_get_opp_table(cpu_dev); > > + if (IS_ERR(devfreq->opp_table)) { > > + ret = PTR_ERR(opp_table); > > + goto out; > > + } > > + > > + state->dev = cpu_dev; > > + state->opp_table = opp_table; > > + state->first_cpu = cpumask_first(policy->related_cpus); > > + state->freq = policy->cur; > > + state->min_freq = policy->cpuinfo.min_freq; > > + state->max_freq = policy->cpuinfo.max_freq; > > + data->cpu_state[cpu] = state; > > Add blank line. > > > + cpufreq_cpu_put(policy); > > + } else { > > + ret = -EPROBE_DEFER; > > + goto out; > > + } > > + } > > Add blank line. Get it. > > +out: > > + put_online_cpus(); > > + if (ret) > > + return ret; > > + > > + /* Update devfreq */ > > + mutex_lock(&devfreq->lock); > > + ret = update_devfreq(devfreq); > > + mutex_unlock(&devfreq->lock); > > + if (ret) > > + dev_err(dev, "Couldn't update the frequency.\n"); > > + > > + return ret; > > +} > > + > > +static int cpufreq_passive_unregister(struct devfreq_passive_data **p_data) > > +{ > > + struct devfreq_passive_data *data = *p_data; > > + struct devfreq_cpu_state *cpu_state; > > + int cpu; > > + > > + if (data->nb.notifier_call) > > + cpufreq_unregister_notifier(&data->nb, > > + CPUFREQ_TRANSITION_NOTIFIER); > > + > > + for_each_possible_cpu(cpu) { > > + cpu_state = data->cpu_state[cpu]; > > + if (cpu_state) { > > + if (cpu_state->opp_table) > > + dev_pm_opp_put_opp_table(cpu_state->opp_table); > > + kfree(cpu_state); > > + cpu_state = NULL; > > + } > > + } > > + > > + return 0; > > +} > > + > > static int devfreq_passive_event_handler(struct devfreq *devfreq, > > unsigned int event, void *data) > > { > > @@ -165,7 +398,7 @@ static int devfreq_passive_event_handler(struct devfreq *devfreq, > > struct notifier_block *nb = &p_data->nb; > > int ret = 0; > > > > - if (!parent) > > + if (p_data->parent_type == DEVFREQ_PARENT_DEV && !parent) > > return -EPROBE_DEFER; > > If you modify the devfreq_passive_event_handler() as following, > you can move this condition for DEVFREQ_PARENT_DEV into > (register|unregister)_parent_dev_notifier. > > switch (event) { > case DEVFREQ_GOV_START: > ret = register_parent_dev_notifier(p_data); > break; > case DEVFREQ_GOV_STOP: > ret = unregister_parent_dev_notifier(p_data); > break; > default: > ret = -EINVAL; > break; > } > > return ret; > Get it. > > > > switch (event) { > > @@ -173,13 +406,24 @@ static int devfreq_passive_event_handler(struct devfreq *devfreq, > > if (!p_data->this) > > p_data->this = devfreq; > > > > - nb->notifier_call = devfreq_passive_notifier_call; > > - ret = devfreq_register_notifier(parent, nb, > > - DEVFREQ_TRANSITION_NOTIFIER); > > + if (p_data->parent_type == DEVFREQ_PARENT_DEV) { > > + nb->notifier_call = devfreq_passive_notifier_call; > > + ret = devfreq_register_notifier(parent, nb, > > + DEVFREQ_TRANSITION_NOTIFIER); > > + } else if (p_data->parent_type == CPUFREQ_PARENT_DEV) { > > + ret = cpufreq_passive_register(&p_data); > > I think that we better to collect the code related to notifier registration > into one function like devfreq_pass_register_notifier() instead of > cpufreq_passive_register() as following: I think it is more simple and readable. > > If you have more proper function name of register_parent_dev_notifier, > please give your opinion. > > int register_parent_dev_notifier(struct devfreq_passive_data **p_data) > switch (p_data->parent_type) { > case DEVFREQ_PARENT_DEV: > nb->notifier_call = devfreq_passive_notifier_call; > ret = devfreq_register_notifier(parent, nb, > break; > case CPUFREQ_PARENT_DEV: > cpufreq_register_notifier(...) > ... > break; > } Not fully understanding. Do you mean expanding cpufreq_passive_register()? I think leave it in function will be with clean for this code segment. > > > > + } else { > > + ret = -EINVAL; > > + } > > break; > > case DEVFREQ_GOV_STOP: > > - WARN_ON(devfreq_unregister_notifier(parent, nb, > > - DEVFREQ_TRANSITION_NOTIFIER)); > > + if (p_data->parent_type == DEVFREQ_PARENT_DEV) > > + WARN_ON(devfreq_unregister_notifier(parent, nb, > > + DEVFREQ_TRANSITION_NOTIFIER)); > > + else if (p_data->parent_type == CPUFREQ_PARENT_DEV) > > + cpufreq_passive_unregister(&p_data); > > + else > > + ret = -EINVAL; > > ditto. unregister_parent_dev_notifier(struct devfreq_passive_data **p_data) Get it. > > > break; > > default: > > break; > > diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h > > index a4b19d593151..04ce576fd6f1 100644 > > --- a/include/linux/devfreq.h > > +++ b/include/linux/devfreq.h > > @@ -278,6 +278,32 @@ struct devfreq_simple_ondemand_data { > > > > #if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE) > > /** > > + * struct devfreq_cpu_state - holds the per-cpu state > > + * @freq: the current frequency of the cpu. > > + * @min_freq: the min frequency of the cpu. > > + * @max_freq: the max frequency of the cpu. > > + * @first_cpu: the cpumask of the first cpu of a policy. > > + * @dev: reference to cpu device. > > + * @opp_table: reference to cpu opp table. > > + * > > + * This structure stores the required cpu_state of a cpu. > > + * This is auto-populated by the governor. > > + */ > > +struct devfreq_cpu_state {> + unsigned int freq; > > It is better to change from 'freq' to 'curr_freq' > for more correct expression. Get it. > > > + unsigned int min_freq; > > + unsigned int max_freq; > > + unsigned int first_cpu; > > + struct device *dev; > > How about changing the name 'dev' to 'cpu_dev'? Okay. > > > > + struct opp_table *opp_table; > > +}; > > devfreq_cpu_state is only handled by within driver/devfreq/governor_passive.c. > > So, you can move it into drivers/devfreq/governor_passive.c > and just add the definition into include/linux/devfreq.h as following: > It is able to prevent the access of variable of 'struct devfreq_cpu_state' > outside. > > struct devfreq_cpu_state; Get it. > > > + > > +enum devfreq_parent_dev_type { > > + DEVFREQ_PARENT_DEV, > > + CPUFREQ_PARENT_DEV, > > +}; > > + > > +/** > > * struct devfreq_passive_data - ``void *data`` fed to struct devfreq > > * and devfreq_add_device > > * @parent: the devfreq instance of parent device. > > @@ -288,13 +314,15 @@ struct devfreq_simple_ondemand_data { > > * using governors except for passive governor. > > * If the devfreq device has the specific method to decide > > * the next frequency, should use this callback. > > - * @this: the devfreq instance of own device. > > - * @nb: the notifier block for DEVFREQ_TRANSITION_NOTIFIER list > > + * @parent_type parent type of the device > > Need to add ':' at the end of word. -> "parent_type:". > > > + * @this: the devfreq instance of own device. > > + * @nb: the notifier block for DEVFREQ_TRANSITION_NOTIFIER list > > I knew that you make them with same indentation. > But, actually, it is not related to this patch like clean-up code. > Even if it is not pretty, you better to don't touch 'this' and 'nb' indentaion. Get it. > > > + * @cpu_state: the state min/max/current frequency of all online cpu's > > * > > * The devfreq_passive_data have to set the devfreq instance of parent > > * device with governors except for the passive governor. But, don't need to > > - * initialize the 'this' and 'nb' field because the devfreq core will handle > > - * them. > > + * initialize the 'this', 'nb' and 'cpu_state' field because the devfreq core > > + * will handle them. > > */ > > struct devfreq_passive_data { > > /* Should set the devfreq instance of parent device */ > > @@ -303,9 +331,13 @@ struct devfreq_passive_data { > > /* Optional callback to decide the next frequency of passvice device */ > > int (*get_target_freq)(struct devfreq *this, unsigned long *freq); > > > > + /* Should set the type of parent device */ > > + enum devfreq_parent_dev_type parent_type; > > + > > /* For passive governor's internal use. Don't need to set them */ > > struct devfreq *this; > > struct notifier_block nb; > > + struct devfreq_cpu_state *cpu_state[NR_CPUS]; > > }; > > #endif > > > > > > _______________________________________________ Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek