On 9/14/25 4:45 AM, Wang Jianzheng wrote:

+#ifdef CONFIG_PM
+static void blk_mq_dev_frequency_work(struct work_struct *work)
+{
+	struct request_queue *q =
+			container_of(work, struct request_queue, dev_freq_work.work);
+	unsigned long timeout;
+	struct dev_pm_qos_request *qos = q->dev_freq_qos;
+
+	timeout = msecs_to_jiffies(q->disk->dev_freq_timeout);
+	if (!q || IS_ERR_OR_NULL(q->dev) || IS_ERR_OR_NULL(qos))
+		return;
+
+	if (q->pm_qos_status == PM_QOS_ACTIVE) {
+		q->pm_qos_status = PM_QOS_FREQ_SET;
+		dev_pm_qos_add_request(q->dev, qos, DEV_PM_QOS_MIN_FREQUENCY,
+				       FREQ_QOS_MAX_DEFAULT_VALUE);
+	} else {
+		if (time_after(jiffies, READ_ONCE(q->last_active) + timeout))
+			q->pm_qos_status = PM_QOS_FREQ_REMOV;
+	}
+
+	if (q->pm_qos_status == PM_QOS_FREQ_REMOV) {
+		dev_pm_qos_remove_request(qos);
+		q->pm_qos_status = PM_QOS_ACTIVE;
+	} else {
+		schedule_delayed_work(&q->dev_freq_work,
+				      q->last_active + timeout - jiffies);
+	}
+}

The above code is similar in nature to the activity detection by the
run-time power management (RPM) code. Why a new timer mechanism instead
of adding more code in the UFS driver RPM callbacks?

Good luck with adding power-management code in the block layer hot path
... I'm not sure anyone will be enthusiast seeing code being added in
blk_mq_submit_bio().

Thanks,

Bart.