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>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index b146d76f04c..4fa1a22c55e 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);
 	}