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Subject[PATCH] PM / devfreq: add relation of recommended frequency.
Date
The semantics of "target frequency" given to devfreq driver from
devfreq framework has always been interpretted as "at least" or GLB
(greatest lower bound). However, the framework might want the
device driver to limit its max frequency (LUB: least upper bound),
especially if it is given by thermal framework (it's too hot).

Thus, the target fuction should have another parameter to express
whether the framework wants GLB or LUB. And, the additional parameter,
"u32 options", does it.

With the update, devfreq_recommended_opp() is also updated.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
drivers/devfreq/devfreq.c | 44 ++++++++++++++++++++++++++++++----------
drivers/devfreq/exynos4_bus.c | 16 +++++++++++---
include/linux/devfreq.h | 18 ++++++++++++++--
3 files changed, 60 insertions(+), 18 deletions(-)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index a33fc6c..83392a6 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -84,6 +84,7 @@ int update_devfreq(struct devfreq *devfreq)
{
unsigned long freq;
int err = 0;
+ u32 options = 0;

if (!mutex_is_locked(&devfreq->lock)) {
WARN(true, "devfreq->lock must be locked by the caller.\n");
@@ -104,18 +105,23 @@ int update_devfreq(struct devfreq *devfreq)
* qos_min_freq
*/

- if (devfreq->qos_min_freq && freq < devfreq->qos_min_freq)
+ if (devfreq->qos_min_freq && freq < devfreq->qos_min_freq) {
freq = devfreq->qos_min_freq;
- if (devfreq->max_freq && freq > devfreq->max_freq)
+ options &= ~(1 << 0);
+ options |= DEVFREQ_OPTION_FREQ_LUB;
+ }
+ if (devfreq->max_freq && freq > devfreq->max_freq) {
freq = devfreq->max_freq;
- if (devfreq->min_freq && freq < devfreq->min_freq)
+ options &= ~(1 << 0);
+ options |= DEVFREQ_OPTION_FREQ_GLB;
+ }
+ if (devfreq->min_freq && freq < devfreq->min_freq) {
freq = devfreq->min_freq;
+ options &= ~(1 << 0);
+ options |= DEVFREQ_OPTION_FREQ_LUB;
+ }

- /*
- * TODO in the devfreq-next:
- * add relation or use rance (freq_min, freq_max)
- */
- err = devfreq->profile->target(devfreq->dev.parent, &freq);
+ err = devfreq->profile->target(devfreq->dev.parent, &freq, options);
if (err)
return err;

@@ -771,14 +777,30 @@ module_exit(devfreq_exit);
* freq value given to target callback.
* @dev The devfreq user device. (parent of devfreq)
* @freq The frequency given to target function
+ * @floor false: find LUB first and use GLB if LUB not available.
+ * true: find GLB first and use LUB if GLB not available.
+ *
+ * LUB: least upper bound (at least this freq or above, but the least)
+ * GLB: greatest lower bound (at most this freq or below, but the most)
*
*/
-struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq)
+struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq,
+ bool floor)
{
- struct opp *opp = opp_find_freq_ceil(dev, freq);
+ struct opp *opp;

- if (opp == ERR_PTR(-ENODEV))
+ if (floor) {
opp = opp_find_freq_floor(dev, freq);
+
+ if (opp == ERR_PTR(-ENODEV))
+ opp = opp_find_freq_ceil(dev, freq);
+ } else {
+ opp = opp_find_freq_ceil(dev, freq);
+
+ if (opp == ERR_PTR(-ENODEV))
+ opp = opp_find_freq_floor(dev, freq);
+ }
+
return opp;
}

diff --git a/drivers/devfreq/exynos4_bus.c b/drivers/devfreq/exynos4_bus.c
index 590d686..c0a78da 100644
--- a/drivers/devfreq/exynos4_bus.c
+++ b/drivers/devfreq/exynos4_bus.c
@@ -619,13 +619,21 @@ static int exynos4_bus_setvolt(struct busfreq_data *data, struct opp *opp,
return err;
}

-static int exynos4_bus_target(struct device *dev, unsigned long *_freq)
+static int exynos4_bus_target(struct device *dev, unsigned long *_freq,
+ u32 options)
{
int err = 0;
- struct busfreq_data *data = dev_get_drvdata(dev);
- struct opp *opp = devfreq_recommended_opp(dev, _freq);
- unsigned long old_freq = opp_get_freq(data->curr_opp);
+ unsigned long def = *_freq;
+ struct platform_device *pdev = container_of(dev, struct platform_device,
+ dev);
+ struct busfreq_data *data = platform_get_drvdata(pdev);
+ struct opp *opp = devfreq_recommended_opp(dev, _freq, options &
+ DEVFREQ_OPTION_FREQ_GLB);
unsigned long freq = opp_get_freq(opp);
+ unsigned long old_freq = opp_get_freq(data->curr_opp);
+
+ if (IS_ERR(opp))
+ return PTR_ERR(opp);

if (old_freq == freq)
return 0;
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index b853379..1aff012 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -59,6 +59,16 @@ struct devfreq_pm_qos_table {
s32 qos_value;
};

+/*
+ * target callback, which is to provide additional information to the
+ * devfreq driver.
+ */
+
+/* The resulting frequency should be at least this. (least upper bound) */
+#define DEVFREQ_OPTION_FREQ_LUB 0x0
+/* The resulting frequency should be at most this. (greatest lower bound) */
+#define DEVFREQ_OPTION_FREQ_GLB 0x1
+
/**
* struct devfreq_dev_profile - Devfreq's user device profile
* @initial_freq The operating frequency when devfreq_add_device() is
@@ -76,6 +86,8 @@ struct devfreq_pm_qos_table {
* higher than any operable frequency, set maximum.
* Before returning, target function should set
* freq at the current frequency.
+ * The "option" parameter's possible values are
+ * explained above with "DEVFREQ_OPTION_*" macros.
* @get_dev_status The device should provide the current performance
* status to devfreq, which is used by governors.
* @exit An optional callback that is called when devfreq
@@ -95,7 +107,7 @@ struct devfreq_dev_profile {
bool qos_use_max;
struct devfreq_pm_qos_table *qos_list;

- int (*target)(struct device *dev, unsigned long *freq);
+ int (*target)(struct device *dev, unsigned long *freq, u32 options);
int (*get_dev_status)(struct device *dev,
struct devfreq_dev_status *stat);
void (*exit)(struct device *dev);
@@ -198,7 +210,7 @@ extern int devfreq_remove_device(struct devfreq *devfreq);

/* Helper functions for devfreq user device driver with OPP. */
extern struct opp *devfreq_recommended_opp(struct device *dev,
- unsigned long *freq);
+ unsigned long *freq, bool floor);
extern int devfreq_register_opp_notifier(struct device *dev,
struct devfreq *devfreq);
extern int devfreq_unregister_opp_notifier(struct device *dev,
@@ -253,7 +265,7 @@ static int devfreq_remove_device(struct devfreq *devfreq)
}

static struct opp *devfreq_recommended_opp(struct device *dev,
- unsigned long *freq)
+ unsigned long *freq, bool floor)
{
return -EINVAL;
}
--
1.7.4.1


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