Commit f9b9e806 authored by Thomas Renninger's avatar Thomas Renninger Committed by Rafael J. Wysocki
Browse files

PM QoS: Make pm_qos settings readable 

I have a machine where entering deep C-states broke.
pm_qos was a hot candidate, but I couldn't find any way to double
check without the need of recompiling.

While in this case it was a driver bug (ath9k):
https://bugzilla.kernel.org/show_bug.cgi?id=27532



powertop or others may want to read out cpu_dma_latency
restrictions which could be the cause of preventing a machine
entering deeper C-states.

Output with this patch:

# default value of 2000 * USEC_PER_SEC (0x77359400)
cat /dev/network_latency |hexdump
0000000 9400 7735
0000004

# value of 55 us which is the reason for not entering C2
cat /dev/cpu_dma_latency |hexdump
0000000 0037 0000
0000004

There is no reason to hide this info -> make pm_qos files readable.

Signed-off-by: default avatarThomas Renninger <trenn@suse.de>
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
parent 7ae49618

kernel/pm_qos_params.c

+24 −0
Original line number Diff line number Diff line
@@ -103,11 +103,14 @@ static struct pm_qos_object *pm_qos_array[] = { 


static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,

		size_t count, loff_t *f_pos);

static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,

		size_t count, loff_t *f_pos);

static int pm_qos_power_open(struct inode *inode, struct file *filp);

static int pm_qos_power_release(struct inode *inode, struct file *filp);



static const struct file_operations pm_qos_power_fops = {

	.write = pm_qos_power_write,

	.read = pm_qos_power_read,

	.open = pm_qos_power_open,

	.release = pm_qos_power_release,

	.llseek = noop_llseek,
@@ -376,6 +379,27 @@ static int pm_qos_power_release(struct inode *inode, struct file *filp) 
}





static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,

		size_t count, loff_t *f_pos)

{

	s32 value;

	unsigned long flags;

	struct pm_qos_object *o;

	struct pm_qos_request_list *pm_qos_req = filp->private_data;;



	if (!pm_qos_req)

		return -EINVAL;

	if (!pm_qos_request_active(pm_qos_req))

		return -EINVAL;



	o = pm_qos_array[pm_qos_req->pm_qos_class];

	spin_lock_irqsave(&pm_qos_lock, flags);

	value = pm_qos_get_value(o);

	spin_unlock_irqrestore(&pm_qos_lock, flags);



	return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));

}



static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,

		size_t count, loff_t *f_pos)

{

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