From mboxrd@z Thu Jan 1 00:00:00 1970 From: MyungJoo Ham Subject: [PATCH v4 2/3] PM / DEVFREQ: add example governors Date: Fri, 15 Jul 2011 17:11:49 +0900 Message-ID: <1310717510-19002-3-git-send-email-myungjoo.ham@samsung.com> References: <1310717510-19002-1-git-send-email-myungjoo.ham@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <1310717510-19002-1-git-send-email-myungjoo.ham@samsung.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: linux-pm@lists.linux-foundation.org Cc: Len Brown , Greg Kroah-Hartman , Kyungmin Park , Thomas Gleixner List-Id: linux-pm@vger.kernel.org Three CPUFREQ-like governors are provided as examples. powersave: use the lowest frequency possible. The user (device) should set the polling_ms as 0 because polling is useless for this governor. performance: use the highest freqeuncy possible. The user (device) should set the polling_ms as 0 because polling is useless for this governor. simple_ondemand: simplified version of CPUFREQ's ONDEMAND governor. When a user updates OPP entries (enable/disable/add), OPP framework automatically notifies DEVFREQ to update operating frequency accordingly. Thus, DEVFREQ users (device drivers) do not need to update DEVFREQ manually with OPP entry updates or set polling_ms for powersave , performance, or any other "static" governors. Signed-off-by: MyungJoo Ham Signed-off-by: Kyungmin Park --- Changes from v3: - Bugfixes on simple-ondemand governor (divide by zero / overflow) - Style fixes - Give names to governors --- drivers/base/power/devfreq.c | 85 ++++++++++++++++++++++++++++++++++++++++++ include/linux/devfreq.h | 5 ++ 2 files changed, 90 insertions(+), 0 deletions(-) diff --git a/drivers/base/power/devfreq.c b/drivers/base/power/devfreq.c index aba9768..e5a73aa 100644 --- a/drivers/base/power/devfreq.c +++ b/drivers/base/power/devfreq.c @@ -395,3 +395,88 @@ static int __init devfreq_init(void) return 0; } late_initcall(devfreq_init); + +static int devfreq_powersave_func(struct devfreq *df, + unsigned long *freq) +{ + *freq = 0; /* devfreq_do will run "ceiling" to 0 */ + return 0; +} + +struct devfreq_governor devfreq_powersave = { + .name = "powersave", + .get_target_freq = devfreq_powersave_func, +}; + +static int devfreq_performance_func(struct devfreq *df, + unsigned long *freq) +{ + *freq = UINT_MAX; /* devfreq_do will run "floor" */ + return 0; +} + +struct devfreq_governor devfreq_performance = { + .name = "performance", + .get_target_freq = devfreq_performance_func, +}; + +/* Constants for DevFreq-Simple-Ondemand (DFSO) */ +#define DFSO_UPTHRESHOLD (90) +#define DFSO_DOWNDIFFERENCTIAL (5) +static int devfreq_simple_ondemand_func(struct devfreq *df, + unsigned long *freq) +{ + struct devfreq_dev_status stat; + int err = df->profile->get_dev_status(df->dev, &stat); + unsigned long long a, b; + + if (err) + return err; + + /* Assume MAX if it is going to be divided by zero */ + if (stat.total_time == 0) { + *freq = UINT_MAX; + return 0; + } + + /* Prevent overflow */ + if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) { + stat.busy_time >>= 7; + stat.total_time >>= 7; + } + + /* Set MAX if it's busy enough */ + if (stat.busy_time * 100 > + stat.total_time * DFSO_UPTHRESHOLD) { + *freq = UINT_MAX; + return 0; + } + + /* Set MAX if we do not know the initial frequency */ + if (stat.current_frequency == 0) { + *freq = UINT_MAX; + return 0; + } + + /* Keep the current frequency */ + if (stat.busy_time * 100 > + stat.total_time * (DFSO_UPTHRESHOLD - DFSO_DOWNDIFFERENCTIAL)) { + *freq = stat.current_frequency; + return 0; + } + + /* Set the desired frequency based on the load */ + a = stat.busy_time; + a *= stat.current_frequency; + b = div_u64(a, stat.total_time); + b *= 100; + b = div_u64(b, (DFSO_UPTHRESHOLD - DFSO_DOWNDIFFERENCTIAL / 2)); + *freq = (unsigned long) b; + + return 0; +} + +struct devfreq_governor devfreq_simple_ondemand = { + .name = "simple_ondemand", + .get_target_freq = devfreq_simple_ondemand_func, +}; diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h index 7c881cc..baa074c 100644 --- a/include/linux/devfreq.h +++ b/include/linux/devfreq.h @@ -84,6 +84,11 @@ extern int devfreq_add_device(struct device *dev, extern int devfreq_remove_device(struct device *dev); extern int devfreq_update(struct device *dev); extern int devfreq_tickle_device(struct device *dev, unsigned long duration_ms); + +extern struct devfreq_governor devfreq_powersave; +extern struct devfreq_governor devfreq_performance; +extern struct devfreq_governor devfreq_simple_ondemand; + #else /* !CONFIG_PM_DEVFREQ */ static int devfreq_add_device(struct device *dev, struct devfreq_dev_profile *profile, -- 1.7.4.1