[PATCH 1/2] regulator: Add API to re-apply voltage to hardware

[PATCH 1/2] regulator: Add API to re-apply voltage to hardware

[Mark Brown]

When cooperating with an external control source the regulator setup
may be changed underneath the API. Currently consumers can just redo
the regulator_set_voltage() to restore a previously set configuration
but provide an explicit API for doing this as optimsations in the
regulator_set_voltage() implementation will shortly prevent that.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
 drivers/regulator/core.c           |   47 ++++++++++++++++++++++++++++++++++++
 include/linux/regulator/consumer.h |    1 +
 2 files changed, 48 insertions(+), 0 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 3d72cc8..a12cba3 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -1727,6 +1727,53 @@ out:
 }
 EXPORT_SYMBOL_GPL(regulator_set_voltage);
 
+/**
+ * regulator_sync_voltage - re-apply last regulator output voltage
+ * @regulator: regulator source
+ *
+ * Re-apply the last configured voltage.  This is intended to be used
+ * where some external control source the consumer is cooperating with
+ * has caused the configured voltage to change.
+ */
+int regulator_sync_voltage(struct regulator *regulator)
+{
+	struct regulator_dev *rdev = regulator->rdev;
+	int ret, min_uV, max_uV;
+
+	mutex_lock(&rdev->mutex);
+
+	if (!rdev->desc->ops->set_voltage &&
+	    !rdev->desc->ops->set_voltage_sel) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* This is only going to work if we've had a voltage configured. */
+	if (!regulator->min_uV && !regulator->max_uV) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	min_uV = regulator->min_uV;
+	max_uV = regulator->max_uV;
+
+	/* This should be a paranoia check... */
+	ret = regulator_check_voltage(rdev, &min_uV, &max_uV);
+	if (ret < 0)
+		goto out;
+
+	ret = regulator_check_consumers(rdev, &min_uV, &max_uV);
+	if (ret < 0)
+		goto out;
+
+	ret = _regulator_do_set_voltage(rdev, min_uV, max_uV);
+
+out:
+	mutex_unlock(&rdev->mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regulator_sync_voltage);
+
 static int _regulator_get_voltage(struct regulator_dev *rdev)
 {
 	int sel;
diff --git a/include/linux/regulator/consumer.h b/include/linux/regulator/consumer.h
index ebd7472..7954f6b 100644
--- a/include/linux/regulator/consumer.h
+++ b/include/linux/regulator/consumer.h
@@ -154,6 +154,7 @@ int regulator_is_supported_voltage(struct regulator *regulator,
 				   int min_uV, int max_uV);
 int regulator_set_voltage(struct regulator *regulator, int min_uV, int max_uV);
 int regulator_get_voltage(struct regulator *regulator);
+int regulator_sync_voltage(struct regulator *regulator);
 int regulator_set_current_limit(struct regulator *regulator,
 			       int min_uA, int max_uA);
 int regulator_get_current_limit(struct regulator *regulator);
-- 
1.7.1

[PATCH 2/2] regulator: Optimise out noop voltage changes

[Mark Brown]

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>
---
 drivers/regulator/core.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index a12cba3..ab419f8 100644
--- 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) {
-- 
1.7.1

Re: [PATCH 1/2] regulator: Add API to re-apply voltage to hardware

[Liam Girdwood]

On Thu, 2010-12-16 at 15:49 +0000, Mark Brown wrote:
> When cooperating with an external control source the regulator setup
> may be changed underneath the API. Currently consumers can just redo
> the regulator_set_voltage() to restore a previously set configuration
> but provide an explicit API for doing this as optimsations in the
> regulator_set_voltage() implementation will shortly prevent that.
> 
> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
> ---

Both Applied.

Thanks

Liam
-- 
Freelance Developer, SlimLogic Ltd
ASoC and Voltage Regulator Maintainer.
http://www.slimlogic.co.uk