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| author | Thomas Renninger <trenn@suse.de> | 2011-02-28 22:06:34 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rjw@sisk.pl> | 2011-03-15 00:43:18 +0100 |
| commit | f9b9e806ae0ede772cbb9916d9ac7354a123d044 (patch) | |
| tree | c855475a3b19f829999f585054e69e35af55655d /kernel | |
| parent | PM / OPP: opp_find_freq_exact() documentation fix (diff) | |
| download | linux-f9b9e806ae0ede772cbb9916d9ac7354a123d044.tar.xz linux-f9b9e806ae0ede772cbb9916d9ac7354a123d044.zip | |
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: Thomas Renninger <trenn@suse.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/pm_qos_params.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c index aeaa7f846821..0da058bff8eb 100644 --- a/kernel/pm_qos_params.c +++ b/kernel/pm_qos_params.c @@ -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) { |