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Wysocki" , Viresh Kumar , Nishanth Menon , Stephen Boyd , Liam Girdwood , Mark Brown Cc: linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, srv_heupstream@mediatek.com, Saravana Kannan , Sibi Sankar From: Chanwoo Choi Organization: Samsung Electronics Message-ID: Date: Thu, 28 May 2020 14:03:22 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:59.0) Gecko/20100101 Thunderbird/59.0 MIME-Version: 1.0 In-Reply-To: <20200520034307.20435-7-andrew-sh.cheng@mediatek.com> Content-Language: en-US Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA02Te0xTVxzHc+6rRS3eFdQDySbejT8gIr3U6oGJWcAsN5nZcI4tGQvdDb2h jL68t9XplqiAk6owiFnUykQ3TRQZLxlFnto1wQ5hw0IhMhKQxrilSLLCxrZkWduLGf99zu98 v/nmex5KXH1Skawss9gF0cKbGGod0fVDWmZGS/5PxZqRp68jd+szEn01F6RQo3eURCMVIQX6 Y7waQx3zARL5exoo5K8cAyhc4wXoxuQYhiqqtGj65E0KhVZGMPRw+BGJTvV7FejfQDuBAtcW SXRvrJ5CF2bUqH2ZeyORa77SDDh/bQ3G3XXNKLiOJifF/RLoo7g7149zVb5BguucOE1wtZ1N gBuacmNcuOOVgvUflu8xCrxBEFMES4nVUGYpzWXeOqjP1+t2adgMNhvtZlIsvFnIZfbtL8h4 s8wUacikHOZNjsiogJckJnPvHtHqsAspRqtkz2UEm8Fky7btkHiz5LCU7iixmnNYjSZLFxF+ XG6ceXzAducb8OniJSd5AniPnwFxSkjvhJPhXuoMWKdU090A/hlaUMiL3wGsWX5KRVVqOgzg lV91Lxx/1fcRsqgHwJbrwVX7IoCz5y9iUVUC/REM9X+JRzmRnsZh3eX3oiKcrsfgwI+nYhsU nQ4Hn03FIjbS2+DEyjyIsoreC+fuuxVRJuhU+H1gKcab6Pehr6tqVfMS9F0KElGOo/Pg4oOL McbpLfBxsBGTeSt0LzTg0WBI346DF0JOIHfYB933Z0mZE+BvQ50KmZNh+Hk/JfNn8JbPS8nm agA7B39eNWjh4I3zkQRlJCENtvZkyuNt8O4/XwM5OB4+Xz5HRiWQVsHqL9Sy5FXon53BZE6C 3552UnWAca2p41pTwbWmguv/sKuAaAKbBZtkLhUk1qZde90dIPb803d3g7bR/R5AKwGzQaXh RovVJH9YOmr2AKjEmURV3shwsVpl4I8eE0SrXnSYBMkDdJHTrseTN5VYI5/JYtezuiytVot2 srt0LMtsUTWuPCxW06W8XSgXBJsgvvBhyrjkEyAvqdf63csfXP6kwX7A8HfhOLxde6TxtUcb Uo8MnK3DsvH1h1KfxC+0bX13YcmZc2x5umKiyM/6DiZ4hgcmy5oPjb8ztFHTUlQoLXU527Tb jehJ39laRzCtdX6zMiupu03v2X6zqD1nKl71uVjZLuT7K8X0xLcLH5wbtptqem/N3WMIyciz 6bgo8f8BtZ7FVxQEAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrPIsWRmVeSWpSXmKPExsWy7bCSnO465/NxBrvXClhsX/+C1WLqwyds FvOPnGO1ONv0ht3i25UOJotNj6+xWlzeNYfN4nLzRUaLz71HGC2WXr/IZNHUYmxxu3EFm8Wb H2eZLM6cvsRq0br3CLvFv2sbWSyuLXzPanHg4kQ2i+l3hSw2fvVwEPFYM28No8flvl4mj52z 7rJ7bFrVyeZx59oeNo/NS+o9Wk7uZ/HYcrWdxaNvyypGj+M3tjN5fN4kF8AdxWWTkpqTWZZa pG+XwJVx91ZgweZFjBXvZ3ayNjAeqe9i5OSQEDCR+DlxDwuILSSwg1Hix65giLikxLSLR5m7 GDmAbGGJw4eLuxi5gEreMkocWLKMGaRGWCBG4s3efmaQhIjAfWaJ5XevsoE4zAITmSTOta9g g2g5yyjxu+cbI0gLm4CWxP4XN9hAbH4BRYmrPx6DxXkF7CQeHtzODmKzCKhKbL32BcwWFQiT 2LnkMRNEjaDEyZlPwE7lFHCSeH9iBpjNLKAu8WfeJWYIW1zi1pP5TBC2vMT2t3OYJzAKz0LS PgtJyywkLbOQtCxgZFnFKJlaUJybnltsWGCUl1quV5yYW1yal66XnJ+7iRGcBrS0djDuWfVB 7xAjEwfjIUYJDmYlEV6ns6fjhHhTEiurUovy44tKc1KLDzFKc7AoifN+nbUwTkggPbEkNTs1 tSC1CCbLxMEp1cCUKbaeRcBHo4Lr9ba01mevOJfWL59cdlz3VVzvySVSie41x7PerHmr8WSL UGqbwqx+TukI9x/uGy02Tub5ePDNR0Uu178lO/pPLjz09DLXUsMbi5odg05+/nXvl/u0GRLF id3Z3u8/V97fyxC3qCmtjm2q57TZZc2rMlZ+frljm9PTpwWVj/VeV72u4uidufCu0e0g5m2T 2qO2Xr2Te7Lz3/7vjqe2l7+e+VBao4rnCMd0vYnuqkrV/E84vJb6HDpxj2uFbfMzBfvzMVOu fn60JHZZw8aQaU8mqEw7sePhkz8PDzx/vCyn++vb02wnm6wyw8zZtZqfH5fK9fjx69Vvzg85 cceyw95tsTh2jDtTZrsSS3FGoqEWc1FxIgCYSUnpcgMAAA== X-CMS-MailID: 20200528045302epcas1p25f00cf42a4ecd907e017f04970ab3566 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20200520034335epcas1p45a321a1a878fb7cd7b9c9ada0a474ef7 References: <20200520034307.20435-1-andrew-sh.cheng@mediatek.com> <20200520034307.20435-7-andrew-sh.cheng@mediatek.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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'. > + 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. > + 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. > + > + 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. > + } 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); > + } > + 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. > + > + 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. > + 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'. > + struct cpufreq_policy *policy; > + struct device *cpu_dev; > + unsigned int cpu; > + int ret; > + > + get_online_cpus(); Add blank line. > + 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. > + 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. > +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; > > 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; } > + } 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) > 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. > + unsigned int min_freq; > + unsigned int max_freq; > + unsigned int first_cpu; > + struct device *dev; How about changing the name 'dev' to 'cpu_dev'? > + 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; > + > +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. > + * @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 > > -- Best Regards, Chanwoo Choi Samsung Electronics