[PATCH V3 1/2] regulator: DT: Add settling time property for non-linear voltage change

[PATCH V3 1/2] regulator: DT: Add settling time property for non-linear voltage change

[Laxman Dewangan]

Some regulators (some PWM regulators) have the voltage transition
exponentially. On such cases, the settling time for voltage change
is treated as constant time.

Add DT property for providing the settling time for any level of
voltage change for non-linear voltage change.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
CC: Douglas Anderson <dianders@chromium.org>
CC: Aleksandr Frid <afrid@nvidia.com>

---
This patch is continuation of discussion on patch
   regulator: pwm: Fix regulator ramp delay for continuous mode
   https://patchwork.kernel.org/patch/9216857/
where is it discussed to have separate property for PWM which has
exponential voltage transition.

Changes from V1:
- Pass the flag to tell that voltage ramp is exponential instead of
  providing delay.

Changes from V2:
- Based on review comment from V1, make the settling time property
  independent of the regulator-ramp-delay and move this out of PWM
  regulator.
---
 Documentation/devicetree/bindings/regulator/regulator.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/regulator/regulator.txt b/Documentation/devicetree/bindings/regulator/regulator.txt
index 6ab5aef..d18edb0 100644
--- a/Documentation/devicetree/bindings/regulator/regulator.txt
+++ b/Documentation/devicetree/bindings/regulator/regulator.txt
@@ -21,6 +21,9 @@ Optional properties:
   design requires. This property describes the total system ramp time
   required due to the combination of internal ramping of the regulator itself,
   and board design issues such as trace capacitance and load on the supply.
+- regulator-settling-time-us: Settling time, in microseconds, for voltage
+  change if regulator have the constant time for any level voltage change.
+  This is useful when regulator have exponential voltage change.
 - regulator-soft-start: Enable soft start so that voltage ramps slowly
 - regulator-state-mem sub-root node for Suspend-to-RAM mode
   : suspend to memory, the device goes to sleep, but all data stored in memory,
-- 
2.1.4

[PATCH V3 2/2] regulator: Add settling time for non-linear voltage transition

[Laxman Dewangan]

Some regulators (some PWM regulators) have the voltage transition
non-linear i.e. exponentially. On such cases, the settling time
for voltage transition can not be presented in the voltage-ramp-delay.

Add new property for non-linear voltage transition and handle this
in getting the voltage settling time.

Signed-off-by: Laxman Dewangan <ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
CC: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
CC: Aleksandr Frid <afrid-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

---
This patch is continuation of discussion on patch
    regulator: pwm: Fix regulator ramp delay for continuous mode
https://patchwork.kernel.org/patch/9216857/
where is it discussed to have separate property for PWM which has
exponential voltage transition.

Changes from V1:
- Use new DT property to finding that voltage ramp is exponential or
  not and use flag for having fixed delay for all voltage change.

Changes from V2:
- Based on review comment from V1, make the settling time property
  independent of the regulator-ramp-delay and move this to core
  framework instead of handling in PWM regulator.
---
 drivers/regulator/core.c          | 2 ++
 drivers/regulator/of_regulator.c  | 4 ++++
 include/linux/regulator/machine.h | 3 +++
 3 files changed, 9 insertions(+)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 67426c0..06a2477 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2752,6 +2752,8 @@ static int _regulator_set_voltage_time(struct regulator_dev *rdev,
 		ramp_delay = rdev->constraints->ramp_delay;
 	else if (rdev->desc->ramp_delay)
 		ramp_delay = rdev->desc->ramp_delay;
+	else if (rdev->constraints->settling_time)
+		return rdev->constraints->settling_time;
 
 	if (ramp_delay == 0) {
 		rdev_warn(rdev, "ramp_delay not set\n");
diff --git a/drivers/regulator/of_regulator.c b/drivers/regulator/of_regulator.c
index 4f613ec..09d677d 100644
--- a/drivers/regulator/of_regulator.c
+++ b/drivers/regulator/of_regulator.c
@@ -86,6 +86,10 @@ static void of_get_regulation_constraints(struct device_node *np,
 			constraints->ramp_disable = true;
 	}
 
+	ret = of_property_read_u32(np, "regulator-settling-time-us", &pval);
+	if (!ret)
+		constraints->settling_time = pval;
+
 	ret = of_property_read_u32(np, "regulator-enable-ramp-delay", &pval);
 	if (!ret)
 		constraints->enable_time = pval;
diff --git a/include/linux/regulator/machine.h b/include/linux/regulator/machine.h
index ad3e515..598a493 100644
--- a/include/linux/regulator/machine.h
+++ b/include/linux/regulator/machine.h
@@ -108,6 +108,8 @@ struct regulator_state {
  * @initial_state: Suspend state to set by default.
  * @initial_mode: Mode to set at startup.
  * @ramp_delay: Time to settle down after voltage change (unit: uV/us)
+ * @settling_time: Time to settle down after voltage change when voltage
+ *		   change is non-linear (unit: microseconds).
  * @active_discharge: Enable/disable active discharge. The enum
  *		      regulator_active_discharge values are used for
  *		      initialisation.
@@ -149,6 +151,7 @@ struct regulation_constraints {
 	unsigned int initial_mode;
 
 	unsigned int ramp_delay;
+	unsigned int settling_time;
 	unsigned int enable_time;
 
 	unsigned int active_discharge;
-- 
2.1.4

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Re: [PATCH V3 1/2] regulator: DT: Add settling time property for non-linear voltage change

[Rob Herring]

On Wed, Nov 23, 2016 at 04:32:39PM +0530, Laxman Dewangan wrote:
> Some regulators (some PWM regulators) have the voltage transition
> exponentially. On such cases, the settling time for voltage change
> is treated as constant time.
> 
> Add DT property for providing the settling time for any level of
> voltage change for non-linear voltage change.
> 
> Signed-off-by: Laxman Dewangan <ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> CC: Douglas Anderson <dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> CC: Aleksandr Frid <afrid-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
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Applied "regulator: DT: Add settling time property for non-linear voltage change" to the regulator tree

[Mark Brown]

The patch

   regulator: DT: Add settling time property for non-linear voltage change

has been applied to the regulator tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From cfd2cedb482ae29ce13a3db46cc24f0c082ca9cf Mon Sep 17 00:00:00 2001
From: Laxman Dewangan <ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Date: Tue, 4 Apr 2017 18:59:49 +0530
Subject: [PATCH] regulator: DT: Add settling time property for non-linear
 voltage change

Some regulators (some PWM regulators) have the voltage transition
exponentially. On such cases, the settling time for voltage change
is treated as constant time.

Add DT property for providing the settling time for any level of
voltage change for non-linear voltage change.

signed-off-by: Laxman Dewangan <ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

Signed-off-by: Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
---
 Documentation/devicetree/bindings/regulator/regulator.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/regulator/regulator.txt b/Documentation/devicetree/bindings/regulator/regulator.txt
index 6ab5aef619d9..d18edb075e1c 100644
--- a/Documentation/devicetree/bindings/regulator/regulator.txt
+++ b/Documentation/devicetree/bindings/regulator/regulator.txt
@@ -21,6 +21,9 @@ Optional properties:
   design requires. This property describes the total system ramp time
   required due to the combination of internal ramping of the regulator itself,
   and board design issues such as trace capacitance and load on the supply.
+- regulator-settling-time-us: Settling time, in microseconds, for voltage
+  change if regulator have the constant time for any level voltage change.
+  This is useful when regulator have exponential voltage change.
 - regulator-soft-start: Enable soft start so that voltage ramps slowly
 - regulator-state-mem sub-root node for Suspend-to-RAM mode
   : suspend to memory, the device goes to sleep, but all data stored in memory,
-- 
2.11.0

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