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authorNishanth Menon <nm@ti.com>2014-12-05 20:19:08 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-01-24 00:16:21 +0300
commitf5f4eda4c9b9e26ec7d7c8ce083e386016ffc0f8 (patch)
treecf25f602ef03fa21f681e7105c05b36cc0025744 /kernel/power/qos.c
parentec6f34e5b552fb0a52e6aae1a5afbbb1605cc6cc (diff)
downloadlinux-f5f4eda4c9b9e26ec7d7c8ce083e386016ffc0f8.tar.xz
PM / QoS: Add debugfs support to view the list of constraints
PM QoS requests are notoriously hard to debug and made even more so due to their highly dynamic nature. Having visibility into the internal data representation per constraint allows us to have much better appreciation of potential issues or bad usage by drivers in the system. So introduce for all classes of PM QoS, an entry in /sys/kernel/debug/pm_qos that shall show all the current requests as well as the snapshot of the value these requests boil down to. For example: ==> /sys/kernel/debug/pm_qos/cpu_dma_latency <== 1: 4444: Active 2: 2000000000: Default 3: 2000000000: Default 4: 2000000000: Default Type=Minimum, Value=4444, Requests: active=1 / total=4 ==> /sys/kernel/debug/pm_qos/memory_bandwidth <== Empty! ... The actual value listed will have their meaning based on the QoS it is on, the 'Type' indicates what logic it would use to collate the information - Minimum, Maximum, or Sum. Value is the collation of all requests. This interface also compares the values with the defaults for the QoS class and marks the ones that are currently active. Signed-off-by: Nishanth Menon <nm@ti.com> Signed-off-by: Dave Gerlach <d-gerlach@ti.com> Acked-by: Kevin Hilman <khilman@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'kernel/power/qos.c')
-rw-r--r--kernel/power/qos.c91
1 files changed, 89 insertions, 2 deletions
diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index 5f4c006c4b1e..97b0df71303e 100644
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -41,6 +41,8 @@
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/kernel.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/export.h>
@@ -182,6 +184,81 @@ static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
c->target_value = value;
}
+static inline int pm_qos_get_value(struct pm_qos_constraints *c);
+static int pm_qos_dbg_show_requests(struct seq_file *s, void *unused)
+{
+ struct pm_qos_object *qos = (struct pm_qos_object *)s->private;
+ struct pm_qos_constraints *c;
+ struct pm_qos_request *req;
+ char *type;
+ unsigned long flags;
+ int tot_reqs = 0;
+ int active_reqs = 0;
+
+ if (IS_ERR_OR_NULL(qos)) {
+ pr_err("%s: bad qos param!\n", __func__);
+ return -EINVAL;
+ }
+ c = qos->constraints;
+ if (IS_ERR_OR_NULL(c)) {
+ pr_err("%s: Bad constraints on qos?\n", __func__);
+ return -EINVAL;
+ }
+
+ /* Lock to ensure we have a snapshot */
+ spin_lock_irqsave(&pm_qos_lock, flags);
+ if (plist_head_empty(&c->list)) {
+ seq_puts(s, "Empty!\n");
+ goto out;
+ }
+
+ switch (c->type) {
+ case PM_QOS_MIN:
+ type = "Minimum";
+ break;
+ case PM_QOS_MAX:
+ type = "Maximum";
+ break;
+ case PM_QOS_SUM:
+ type = "Sum";
+ break;
+ default:
+ type = "Unknown";
+ }
+
+ plist_for_each_entry(req, &c->list, node) {
+ char *state = "Default";
+
+ if ((req->node).prio != c->default_value) {
+ active_reqs++;
+ state = "Active";
+ }
+ tot_reqs++;
+ seq_printf(s, "%d: %d: %s\n", tot_reqs,
+ (req->node).prio, state);
+ }
+
+ seq_printf(s, "Type=%s, Value=%d, Requests: active=%d / total=%d\n",
+ type, pm_qos_get_value(c), active_reqs, tot_reqs);
+
+out:
+ spin_unlock_irqrestore(&pm_qos_lock, flags);
+ return 0;
+}
+
+static int pm_qos_dbg_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, pm_qos_dbg_show_requests,
+ inode->i_private);
+}
+
+static const struct file_operations pm_qos_debug_fops = {
+ .open = pm_qos_dbg_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
/**
* pm_qos_update_target - manages the constraints list and calls the notifiers
* if needed
@@ -509,12 +586,17 @@ int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier)
EXPORT_SYMBOL_GPL(pm_qos_remove_notifier);
/* User space interface to PM QoS classes via misc devices */
-static int register_pm_qos_misc(struct pm_qos_object *qos)
+static int register_pm_qos_misc(struct pm_qos_object *qos, struct dentry *d)
{
qos->pm_qos_power_miscdev.minor = MISC_DYNAMIC_MINOR;
qos->pm_qos_power_miscdev.name = qos->name;
qos->pm_qos_power_miscdev.fops = &pm_qos_power_fops;
+ if (d) {
+ (void)debugfs_create_file(qos->name, S_IRUGO, d,
+ (void *)qos, &pm_qos_debug_fops);
+ }
+
return misc_register(&qos->pm_qos_power_miscdev);
}
@@ -608,11 +690,16 @@ static int __init pm_qos_power_init(void)
{
int ret = 0;
int i;
+ struct dentry *d;
BUILD_BUG_ON(ARRAY_SIZE(pm_qos_array) != PM_QOS_NUM_CLASSES);
+ d = debugfs_create_dir("pm_qos", NULL);
+ if (IS_ERR_OR_NULL(d))
+ d = NULL;
+
for (i = PM_QOS_CPU_DMA_LATENCY; i < PM_QOS_NUM_CLASSES; i++) {
- ret = register_pm_qos_misc(pm_qos_array[i]);
+ ret = register_pm_qos_misc(pm_qos_array[i], d);
if (ret < 0) {
printk(KERN_ERR "pm_qos_param: %s setup failed\n",
pm_qos_array[i]->name);