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Wed, 02 Oct 2019 15:22:06 -0700 (PDT) Date: Wed, 2 Oct 2019 15:22:04 -0700 From: Matthias Kaehlcke To: Leonard Crestez Subject: Re: [PATCH v9 7/8] PM / devfreq: Add PM QoS support Message-ID: <20191002222204.GH87296@google.com> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191002_152209_033126_CFA884BF X-CRM114-Status: GOOD ( 24.84 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Artur =?utf-8?B?xZp3aWdvxYQ=?= , Abel Vesa , Saravana Kannan , linux-pm@vger.kernel.org, Viresh Kumar , NXP Linux Team , Krzysztof Kozlowski , Lukasz Luba , Chanwoo Choi , Kyungmin Park , MyungJoo Ham , Alexandre Bailon , Georgi Djakov , linux-arm-kernel@lists.infradead.org, Jacky Bai Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Oct 02, 2019 at 10:25:10PM +0300, Leonard Crestez wrote: > Register notifiers with the PM QoS framework in order to respond to > requests for DEV_PM_QOS_MIN_FREQUENCY and DEV_PM_QOS_MAX_FREQUENCY. > > No notifiers are added by this patch but PM QoS constraints can be > imposed externally (for example from other devices). > > Signed-off-by: Leonard Crestez > --- > drivers/devfreq/devfreq.c | 78 +++++++++++++++++++++++++++++++++++++++ > include/linux/devfreq.h | 5 +++ > 2 files changed, 83 insertions(+) > > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c > index 2d63692903ff..46f699b84a22 100644 > --- a/drivers/devfreq/devfreq.c > +++ b/drivers/devfreq/devfreq.c > @@ -22,15 +22,18 @@ > #include > #include > #include > #include > #include > +#include > #include "governor.h" > > #define CREATE_TRACE_POINTS > #include > > +#define HZ_PER_KHZ 1000 > + > static struct class *devfreq_class; > > /* > * devfreq core provides delayed work based load monitoring helper > * functions. Governors can use these or can implement their own > @@ -109,10 +112,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq) > static void get_freq_range(struct devfreq *devfreq, > unsigned long *min_freq, > unsigned long *max_freq) > { > unsigned long *freq_table = devfreq->profile->freq_table; > + s32 qos_min_freq, qos_max_freq; > > lockdep_assert_held(&devfreq->lock); > > /* > * Initialize minimum/maximum frequency from freq table. > @@ -125,10 +129,20 @@ static void get_freq_range(struct devfreq *devfreq, > } else { > *min_freq = freq_table[devfreq->profile->max_state - 1]; > *max_freq = freq_table[0]; > } > > + /* Apply constraints from PM QoS */ > + qos_min_freq = dev_pm_qos_read_value(devfreq->dev.parent, > + DEV_PM_QOS_MIN_FREQUENCY); > + qos_max_freq = dev_pm_qos_read_value(devfreq->dev.parent, > + DEV_PM_QOS_MAX_FREQUENCY); > + *min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq); > + if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE) > + *max_freq = min(*max_freq, > + (unsigned long)HZ_PER_KHZ * qos_max_freq); > + > /* Apply constraints from sysfs */ > *min_freq = max(*min_freq, devfreq->min_freq); > *max_freq = min(*max_freq, devfreq->max_freq); > > /* Apply constraints from OPP interface */ > @@ -608,24 +622,75 @@ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type, > err); > > return NOTIFY_OK; > } > > +/** > + * qos_notifier_call() - Common handler for QoS constraints. > + * @devfreq: the devfreq instance. > + */ > +static int qos_notifier_call(struct devfreq *devfreq) > +{ > + int err; > + > + mutex_lock(&devfreq->lock); > + err = update_devfreq(devfreq); > + mutex_unlock(&devfreq->lock); > + if (err) > + dev_err(devfreq->dev.parent, > + "failed to update frequency from PM QoS (%d)\n", > + err); > + > + return NOTIFY_OK; > +} > + > +/** > + * qos_min_notifier_call() - Callback for QoS min_freq changes. > + * @nb: Should be devfreq->nb_min > + */ > +static int qos_min_notifier_call(struct notifier_block *nb, > + unsigned long val, void *ptr) > +{ > + return qos_notifier_call(container_of(nb, struct devfreq, nb_min)); > +} > + > +/** > + * qos_max_notifier_call() - Callback for QoS max_freq changes. > + * @nb: Should be devfreq->nb_max > + */ > +static int qos_max_notifier_call(struct notifier_block *nb, > + unsigned long val, void *ptr) > +{ > + return qos_notifier_call(container_of(nb, struct devfreq, nb_max)); > +} > + > /** > * devfreq_dev_release() - Callback for struct device to release the device. > * @dev: the devfreq device > * > * Remove devfreq from the list and release its resources. > */ > static void devfreq_dev_release(struct device *dev) > { > struct devfreq *devfreq = to_devfreq(dev); > + int err; > > mutex_lock(&devfreq_list_lock); > list_del(&devfreq->node); > mutex_unlock(&devfreq_list_lock); > > + err = dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_max, > + DEV_PM_QOS_MAX_FREQUENCY); > + if (err) > + dev_warn(dev->parent, "Failed to remove DEV_PM_QOS_MAX_FREQUENCY notifier: %d\n", > + err); > + err = dev_pm_qos_remove_notifier(devfreq->dev.parent, &devfreq->nb_min, > + DEV_PM_QOS_MIN_FREQUENCY); > + if (err) > + dev_warn(dev->parent, "Failed to remove DEV_PM_QOS_MIN_FREQUENCY notifier: %d\n", > + err); > + > if (devfreq->profile->exit) > devfreq->profile->exit(devfreq->dev.parent); > I was concerned there might be a race where the notifier is still running, but I confirmed that dev_pm_qos_mtx is held by dev_pm_qos_remove_notifier() and also when the notifiers are called. > kfree(devfreq->time_in_state); > kfree(devfreq->trans_table); > @@ -735,10 +800,22 @@ struct devfreq *devfreq_add_device(struct device *dev, > if (err) { > put_device(&devfreq->dev); > goto err_out; > } > > + devfreq->nb_min.notifier_call = qos_min_notifier_call; > + err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_min, > + DEV_PM_QOS_MIN_FREQUENCY); > + if (err) > + goto err_devfreq; > + > + devfreq->nb_max.notifier_call = qos_max_notifier_call; > + err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_max, > + DEV_PM_QOS_MAX_FREQUENCY); > + if (err) > + goto err_devfreq; > + > mutex_lock(&devfreq_list_lock); > > governor = try_then_request_governor(devfreq->governor_name); > if (IS_ERR(governor)) { > dev_err(dev, "%s: Unable to find governor for the device\n", > @@ -762,10 +839,11 @@ struct devfreq *devfreq_add_device(struct device *dev, > > return devfreq; > > err_init: > mutex_unlock(&devfreq_list_lock); > +err_devfreq: > devfreq_remove_device(devfreq); > return ERR_PTR(err); > > err_dev: > /* > diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h > index 2bae9ed3c783..8b92ccbd1962 100644 > --- a/include/linux/devfreq.h > +++ b/include/linux/devfreq.h > @@ -134,10 +134,12 @@ struct devfreq_dev_profile { > * @total_trans: Number of devfreq transitions > * @trans_table: Statistics of devfreq transitions > * @time_in_state: Statistics of devfreq states > * @last_stat_updated: The last time stat updated > * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier > + * @nb_min: Notifier block for DEV_PM_QOS_MIN_FREQUENCY > + * @nb_max: Notifier block for DEV_PM_QOS_MAX_FREQUENCY > * > * This structure stores the devfreq information for a give device. > * > * Note that when a governor accesses entries in struct devfreq in its > * functions except for the context of callbacks defined in struct > @@ -176,10 +178,13 @@ struct devfreq { > unsigned int *trans_table; > unsigned long *time_in_state; > unsigned long last_stat_updated; > > struct srcu_notifier_head transition_notifier_list; > + > + struct notifier_block nb_min; > + struct notifier_block nb_max; > }; > > struct devfreq_freqs { > unsigned long old; > unsigned long new; > -- > 2.17.1 > Reviewed-by: Matthias Kaehlcke _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel