On 20 August 2012 15:15, 함명주 myungjoo.ham@samsung.com wrote:
Devfreq returns governor predicted frequency as current frequency via sysfs interface. But device may not support all frequencies that governor predicts. As per the design its driver responsibility to maintain current frequency at which device is operating. So add a callback in device profile to fix this.
Signed-off-by: Rajagopal Venkat rajagopal.venkat@linaro.org
We still need to support "intended frequency".
The "cur_freq" node is to show the intended frequency. As told before, you need to make additional API and ABI for the "actual frequency".
I don't think userspace will be interested in "intended frequency", i.e governor predicted next target frequency unless code is being debugged. More over device may not support all opps that governor predicts. Hence cur_freq node is fixed to show freq at the which device is operating.
Let me know if you still think, intended frequency should be exposed to userspace.
Like CPUfreq, (scaling_cur_freq vs cpuinfo_cur_freq) device driver developers are often very interested in such values. At least for me, such information has been very helpful for production kernels.
Cheers! MyungJoo
Cheers! MyungJoo
drivers/devfreq/devfreq.c | 14 ++++++++++++-- include/linux/devfreq.h | 6 +++--- 2 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index 375b5aa1..798e8ca 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -176,7 +176,6 @@ struct devfreq *devfreq_add_device(struct device *dev, devfreq->dev.release = devfreq_dev_release; devfreq->profile = profile; devfreq->governor = governor;
devfreq->previous_freq = profile->initial_freq; devfreq->governor_data = data; devfreq->nb.notifier_call = devfreq_notifier_call; devfreq->min_freq = profile->min_freq;@@ -272,7 +271,18 @@ static ssize_t show_governor(struct device *dev, static ssize_t show_freq(struct device *dev, struct device_attribute *attr, char *buf) {
return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
int ret;unsigned long freq;struct devfreq *devfreq = to_devfreq(dev);if (devfreq->profile->get_cur_freq) {ret = devfreq->profile->get_cur_freq(devfreq->dev.parent,&freq);if (!ret)return sprintf(buf, "%lu\n", freq);}return sprintf(buf, "<unknown>");}
static ssize_t store_min_freq(struct device *dev, struct device_attribute *attr, diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h index 7c6517f..43f111f 100644 --- a/include/linux/devfreq.h +++ b/include/linux/devfreq.h @@ -76,6 +76,8 @@ struct devfreq_dev_status {
explained above with "DEVFREQ_FLAG_*" macros.- @get_dev_status The device should provide the current performance
status to devfreq, which is used by governors.
- @get_cur_freq The device should provide the current frequency
at which it is operating.- @exit An optional callback that is called when devfreq
is removing the devfreq object due to error orfrom devfreq_remove_device() call. If the user@@ -91,6 +93,7 @@ struct devfreq_dev_profile { int (*target)(struct device *dev, unsigned long *freq, u32 flags); int (*get_dev_status)(struct device *dev, struct devfreq_dev_status *stat);
int (*get_cur_freq)(struct device *dev, unsigned long *freq); void (*exit)(struct device *dev);};
@@ -119,7 +122,6 @@ struct devfreq_governor {
- @nb notifier block used to notify devfreq object that it should
reevaluate operable frequencies. Devfreq users may usedevfreq.nb to the corresponding register notifier call chain.
- @previous_freq previously configured frequency value.
- @governor_data Private data of the governor. The devfreq framework
does not touch this.- @min_freq Limit minimum frequency requested by user (0: none)
@@ -142,8 +144,6 @@ struct devfreq { const struct devfreq_governor *governor; struct notifier_block nb;
unsigned long previous_freq;void *governor_data; /* private data for governors */ unsigned long min_freq;-- 1.7.11.3
-- Regards, Rajagopal