regulator: Optimise out noop voltage changes

If a consumer sets the same voltage range as is currently configured
for that consumer there's no need to run through setting the voltage
again. This pattern may occur with some CPUfreq implementations where
the same voltage range is used for multiple frequencies.

Reported-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index a12cba32460e210bd9c56b0c494de4f2d320365a..ab419f8b2a84c3cf19961fa098cda8a22a35bc54 100644 (file)
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1697,10 +1697,17 @@ static int _regulator_do_set_voltage(struct regulator_dev *rdev,
 int regulator_set_voltage(struct regulator *regulator, int min_uV, int max_uV)
 {
        struct regulator_dev *rdev = regulator->rdev;
-       int ret;
+       int ret = 0;
 
        mutex_lock(&rdev->mutex);
 
+       /* If we're setting the same range as last time the change
+        * should be a noop (some cpufreq implementations use the same
+        * voltage for multiple frequencies, for example).
+        */
+       if (regulator->min_uV == min_uV && regulator->max_uV == max_uV)
+               goto out;
+
        /* sanity check */
        if (!rdev->desc->ops->set_voltage &&
            !rdev->desc->ops->set_voltage_sel) {