PM / OPP: predictable fail results for opp_find* functions, v2

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:
The search fails when an unregistered device pointer is provided.
This is a trigger to change the search direction and search for
a better fit, however, if we cannot differentiate between a valid
search range failure Vs an unregistered device, second search goes
through the same fail return condition. This can be avoided by
appropriate handling of error return code.

With this change, we also fix devfreq for the improved search
strategy with updated error code.

Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index 66888861f9eb1a0fdb34bbeaaf88f99cd005a642..c8a908b099c0e1074e7a0342271a353c934d8d94 100644 (file)
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -235,7 +235,10 @@ 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
@@ -254,7 +257,7 @@ 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)) {
@@ -284,7 +287,11 @@ 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
@@ -295,7 +302,7 @@ 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);
@@ -304,7 +311,7 @@ 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) {
@@ -327,7 +334,11 @@ 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
@@ -338,7 +349,7 @@ 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);
@@ -347,7 +358,7 @@ 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 b146d76f04cfaf9361f3e9ebd767d5c99e8e45d6..4fa1a22c55eabe578cb8e285d0630290c957a891 100644 (file)
--- 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);
        }