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Date: Thu, 11 Oct 2012 08:40:03 -0500
From: Nishanth Menon <nm@...com>
To: <linux-pm@...r.kernel.org>
CC: Nishanth Menon <nm@...com>,
MyungJoo Ham <myungjoo.ham@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
"Rafael J. Wysocki" <rjw@...k.pl>, Kevin Hilman <khilman@...com>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH] PM / OPP: predictable fail results for opp_find* functions
Currently the opp_find* functions return -ENODEV when:
a) it cant find a device (e.g. request for an OPP search on device
which was not registered)
b) When it cant find a match for the search strategy used
This makes life a little in-efficient for users such as devfreq
to make reasonable judgement before switching search strategies.
So, standardize the return results as following:
-EINVAL for bad pointer parameters
-ENODEV when device cannot be found
-ERANGE when search fails
This has the following benefit for devfreq implementation:
Current code:
opp = opp_find_freq_floor(dev, freq);
/* Following search triggers even for un-registered device */
if (opp == ERR_PTR(-ENODEV))
opp = opp_find_freq_ceil(dev, freq);
Vs (after this change):
opp = opp_find_freq_floor(dev, freq);
/* Will only be triggered if search logic fails: intended usage */
if (opp == ERR_PTR(-ERANGE))
opp = opp_find_freq_ceil(dev, freq);
Cc: MyungJoo Ham <myungjoo.ham@...sung.com>
Cc: Kyungmin Park <kyungmin.park@...sung.com>
Cc: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: Kevin Hilman <khilman@...com>
Cc: linux-pm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Nishanth Menon <nm@...com>
---
drivers/base/power/opp.c | 27 +++++++++++++++++++--------
drivers/devfreq/devfreq.c | 4 ++--
2 files changed, 21 insertions(+), 10 deletions(-)
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index 04d443f..a60a8d1 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -233,7 +233,10 @@ EXPORT_SYMBOL(opp_get_opp_count);
*
* Searches for exact match in the opp list and returns pointer to the matching
* opp if found, else returns ERR_PTR in case of error and should be handled
- * using IS_ERR.
+ * using IS_ERR. Error return values can be:
+ * EINVAL: for bad pointer
+ * ERANGE: no match found for search
+ * ENODEV: if device not found in list of registered devices
*
* Note: available is a modifier for the search. if available=true, then the
* match is for exact matching frequency and is available in the stored OPP
@@ -252,7 +255,7 @@ struct opp *opp_find_freq_exact(struct device *dev, unsigned long freq,
bool available)
{
struct device_opp *dev_opp;
- struct opp *temp_opp, *opp = ERR_PTR(-ENODEV);
+ struct opp *temp_opp, *opp = ERR_PTR(-ERANGE);
dev_opp = find_device_opp(dev);
if (IS_ERR(dev_opp)) {
@@ -282,7 +285,11 @@ EXPORT_SYMBOL(opp_find_freq_exact);
* for a device.
*
* Returns matching *opp and refreshes *freq accordingly, else returns
- * ERR_PTR in case of error and should be handled using IS_ERR.
+ * ERR_PTR in case of error and should be handled using IS_ERR. Error return
+ * values can be:
+ * EINVAL: for bad pointer
+ * ERANGE: no match found for search
+ * ENODEV: if device not found in list of registered devices
*
* Locking: This function must be called under rcu_read_lock(). opp is a rcu
* protected pointer. The reason for the same is that the opp pointer which is
@@ -293,7 +300,7 @@ EXPORT_SYMBOL(opp_find_freq_exact);
struct opp *opp_find_freq_ceil(struct device *dev, unsigned long *freq)
{
struct device_opp *dev_opp;
- struct opp *temp_opp, *opp = ERR_PTR(-ENODEV);
+ struct opp *temp_opp, *opp = ERR_PTR(-ERANGE);
if (!dev || !freq) {
dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
@@ -302,7 +309,7 @@ struct opp *opp_find_freq_ceil(struct device *dev, unsigned long *freq)
dev_opp = find_device_opp(dev);
if (IS_ERR(dev_opp))
- return opp;
+ return ERR_CAST(dev_opp);
list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
if (temp_opp->available && temp_opp->rate >= *freq) {
@@ -325,7 +332,11 @@ EXPORT_SYMBOL(opp_find_freq_ceil);
* for a device.
*
* Returns matching *opp and refreshes *freq accordingly, else returns
- * ERR_PTR in case of error and should be handled using IS_ERR.
+ * ERR_PTR in case of error and should be handled using IS_ERR. Error return
+ * values can be:
+ * EINVAL: for bad pointer
+ * ERANGE: no match found for search
+ * ENODEV: if device not found in list of registered devices
*
* Locking: This function must be called under rcu_read_lock(). opp is a rcu
* protected pointer. The reason for the same is that the opp pointer which is
@@ -336,7 +347,7 @@ EXPORT_SYMBOL(opp_find_freq_ceil);
struct opp *opp_find_freq_floor(struct device *dev, unsigned long *freq)
{
struct device_opp *dev_opp;
- struct opp *temp_opp, *opp = ERR_PTR(-ENODEV);
+ struct opp *temp_opp, *opp = ERR_PTR(-ERANGE);
if (!dev || !freq) {
dev_err(dev, "%s: Invalid argument freq=%p\n", __func__, freq);
@@ -345,7 +356,7 @@ struct opp *opp_find_freq_floor(struct device *dev, unsigned long *freq)
dev_opp = find_device_opp(dev);
if (IS_ERR(dev_opp))
- return opp;
+ return ERR_CAST(dev_opp);
list_for_each_entry_rcu(temp_opp, &dev_opp->opp_list, node) {
if (temp_opp->available) {
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index e4d48d2..3838f99 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -656,14 +656,14 @@ struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq,
opp = opp_find_freq_floor(dev, freq);
/* If not available, use the closest opp */
- if (opp == ERR_PTR(-ENODEV))
+ if (opp == ERR_PTR(-ERANGE))
opp = opp_find_freq_ceil(dev, freq);
} else {
/* The freq is an lower bound. opp should be higher */
opp = opp_find_freq_ceil(dev, freq);
/* If not available, use the closest opp */
- if (opp == ERR_PTR(-ENODEV))
+ if (opp == ERR_PTR(-ERANGE))
opp = opp_find_freq_floor(dev, freq);
}
--
1.7.9.5
--
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