| Message ID | 1351207963-30075-1-git-send-email-nm@ti.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Thursday, October 25, 2012 06:32:43 PM Nishanth Menon wrote: > devfreq governors such as ondemand are controlled by a min and > max frequency, while governors like userspace governor allow us > to set a specific frequency. > However, for the same specific device, depending on the SoC, the > available frequencies can vary. > > So expose the available frequencies as a snapshot over sysfs to > allow informed decisions. > > This was inspired by cpufreq framework's equivalent for similar > usage sysfs node: scaling_available_frequencies. > > Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org> > Cc: MyungJoo Ham <myungjoo.ham@samsung.com> > Cc: Kyungmin Park <kyungmin.park@samsung.com> > Cc: "Rafael J. Wysocki" <rjw@sisk.pl> > Cc: Kevin Hilman <khilman@ti.com> > Cc: linux-pm@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > > Signed-off-by: Nishanth Menon <nm@ti.com> > --- > Applies on top of Rafael's linux-next branch: > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git > linux-next b960e9a Merge branch 'pm-sleep-next' into linux-next > > Example output from Beagleboard XM (3730) using a dummy test driver > http://pastebin.pandaboard.org/index.php/view/85100576 : > > /sys/devices/platform/iva.0/devfreq/iva.0 # cat available_frequencies > 260000000 520000000 660000000 > > Documentation/ABI/testing/sysfs-class-devfreq | 9 +++++++++ > drivers/devfreq/devfreq.c | 26 +++++++++++++++++++++++++ > 2 files changed, 35 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq > index e6cf08e..e672ccb 100644 > --- a/Documentation/ABI/testing/sysfs-class-devfreq > +++ b/Documentation/ABI/testing/sysfs-class-devfreq > @@ -51,3 +51,12 @@ Description: > The /sys/class/devfreq/.../userspace/set_freq shows and > sets the requested frequency for the devfreq object if > userspace governor is in effect. > + > +What: /sys/class/devfreq/.../available_frequencies > +Date: October 2012 > +Contact: Nishanth Menon <nm@ti.com> > +Description: > + The /sys/class/devfreq/.../available_frequencies shows > + the available frequencies of the corresponding devfreq object. > + This is a snapshot of available frequencies and not limited > + by the min/max frequency restrictions. > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c > index d02ee7e..2f6ad6b 100644 > --- a/drivers/devfreq/devfreq.c > +++ b/drivers/devfreq/devfreq.c > @@ -571,9 +571,35 @@ static ssize_t show_max_freq(struct device *dev, struct device_attribute *attr, > return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq); > } > > +static ssize_t show_available_freqs(struct device *d, > + struct device_attribute *attr, > + char *buf) > +{ > + struct devfreq *df = to_devfreq(d); > + struct device *dev = df->dev.parent; > + struct opp *opp; > + ssize_t count = 0; > + unsigned long freq = 0; > + > + rcu_read_lock(); > + do { > + opp = opp_find_freq_ceil(dev, &freq); > + if (IS_ERR(opp)) > + break; > + > + count += sprintf(&buf[count], "%lu ", freq); > + freq++; > + } while (1); > + rcu_read_unlock(); > + count += sprintf(&buf[count], "\n"); Care to avoid printing the tailing space? Rafael > + > + return count; > +} > + > static struct device_attribute devfreq_attrs[] = { > __ATTR(governor, S_IRUGO, show_governor, NULL), > __ATTR(cur_freq, S_IRUGO, show_freq, NULL), > + __ATTR(available_frequencies, S_IRUGO, show_available_freqs, NULL), > __ATTR(target_freq, S_IRUGO, show_target_freq, NULL), > __ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval, > store_polling_interval), >
On 01:56-20121026, Rafael J. Wysocki wrote: > On Thursday, October 25, 2012 06:32:43 PM Nishanth Menon wrote: [..] > > +static ssize_t show_available_freqs(struct device *d, > > + struct device_attribute *attr, > > + char *buf) > > +{ > > + struct devfreq *df = to_devfreq(d); > > + struct device *dev = df->dev.parent; > > + struct opp *opp; > > + ssize_t count = 0; > > + unsigned long freq = 0; > > + > > + rcu_read_lock(); > > + do { > > + opp = opp_find_freq_ceil(dev, &freq); > > + if (IS_ERR(opp)) > > + break; > > + > > + count += sprintf(&buf[count], "%lu ", freq); > > + freq++; > > + } while (1); > > + rcu_read_unlock(); > > + count += sprintf(&buf[count], "\n"); > > Care to avoid printing the tailing space? count -= count ? 1 : 0; count += sprintf(&buf[count], "\n"); should take care of empty list and the trailing space. Sounds reasonable?
On Thursday, October 25, 2012 07:03:21 PM Nishanth Menon wrote: > On 01:56-20121026, Rafael J. Wysocki wrote: > > On Thursday, October 25, 2012 06:32:43 PM Nishanth Menon wrote: > [..] > > > +static ssize_t show_available_freqs(struct device *d, > > > + struct device_attribute *attr, > > > + char *buf) > > > +{ > > > + struct devfreq *df = to_devfreq(d); > > > + struct device *dev = df->dev.parent; > > > + struct opp *opp; > > > + ssize_t count = 0; > > > + unsigned long freq = 0; > > > + > > > + rcu_read_lock(); > > > + do { > > > + opp = opp_find_freq_ceil(dev, &freq); > > > + if (IS_ERR(opp)) > > > + break; > > > + > > > + count += sprintf(&buf[count], "%lu ", freq); > > > + freq++; > > > + } while (1); > > > + rcu_read_unlock(); > > > + count += sprintf(&buf[count], "\n"); > > > > Care to avoid printing the tailing space? > count -= count ? 1 : 0; What about if (count) count--; instead? > count += sprintf(&buf[count], "\n"); > should take care of empty list and the trailing space. Sounds reasonable? Thanks, Rafael
diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq index e6cf08e..e672ccb 100644 --- a/Documentation/ABI/testing/sysfs-class-devfreq +++ b/Documentation/ABI/testing/sysfs-class-devfreq @@ -51,3 +51,12 @@ Description: The /sys/class/devfreq/.../userspace/set_freq shows and sets the requested frequency for the devfreq object if userspace governor is in effect. + +What: /sys/class/devfreq/.../available_frequencies +Date: October 2012 +Contact: Nishanth Menon <nm@ti.com> +Description: + The /sys/class/devfreq/.../available_frequencies shows + the available frequencies of the corresponding devfreq object. + This is a snapshot of available frequencies and not limited + by the min/max frequency restrictions. diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index d02ee7e..2f6ad6b 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -571,9 +571,35 @@ static ssize_t show_max_freq(struct device *dev, struct device_attribute *attr, return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq); } +static ssize_t show_available_freqs(struct device *d, + struct device_attribute *attr, + char *buf) +{ + struct devfreq *df = to_devfreq(d); + struct device *dev = df->dev.parent; + struct opp *opp; + ssize_t count = 0; + unsigned long freq = 0; + + rcu_read_lock(); + do { + opp = opp_find_freq_ceil(dev, &freq); + if (IS_ERR(opp)) + break; + + count += sprintf(&buf[count], "%lu ", freq); + freq++; + } while (1); + rcu_read_unlock(); + count += sprintf(&buf[count], "\n"); + + return count; +} + static struct device_attribute devfreq_attrs[] = { __ATTR(governor, S_IRUGO, show_governor, NULL), __ATTR(cur_freq, S_IRUGO, show_freq, NULL), + __ATTR(available_frequencies, S_IRUGO, show_available_freqs, NULL), __ATTR(target_freq, S_IRUGO, show_target_freq, NULL), __ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval, store_polling_interval),
devfreq governors such as ondemand are controlled by a min and max frequency, while governors like userspace governor allow us to set a specific frequency. However, for the same specific device, depending on the SoC, the available frequencies can vary. So expose the available frequencies as a snapshot over sysfs to allow informed decisions. This was inspired by cpufreq framework's equivalent for similar usage sysfs node: scaling_available_frequencies. Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org> Cc: MyungJoo Ham <myungjoo.ham@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Kevin Hilman <khilman@ti.com> Cc: linux-pm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Nishanth Menon <nm@ti.com> --- Applies on top of Rafael's linux-next branch: git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git linux-next b960e9a Merge branch 'pm-sleep-next' into linux-next Example output from Beagleboard XM (3730) using a dummy test driver http://pastebin.pandaboard.org/index.php/view/85100576 : /sys/devices/platform/iva.0/devfreq/iva.0 # cat available_frequencies 260000000 520000000 660000000 Documentation/ABI/testing/sysfs-class-devfreq | 9 +++++++++ drivers/devfreq/devfreq.c | 26 +++++++++++++++++++++++++ 2 files changed, 35 insertions(+)