linux-kernel - [PATCH] regulator: lp87565: Add margin while populating ramp

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Date:   Tue, 17 Apr 2018 13:48:11 +0530
From:   Keerthy <j-keerthy@...com>
To:     <broonie@...nel.org>
CC:     <j-keerthy@...com>, <linux-kernel@...r.kernel.org>,
        <linux-omap@...r.kernel.org>, <t-kristo@...com>
Subject: [PATCH] regulator: lp87565: Add margin while populating ramp_delay

The slew rate might need a +/- 15% margin as per the latest data manual:

	http://www.ti.com/lit/ds/snvsb22/snvsb22.pdf

Hence take a conservative approach to program 85% of the original
hardware slew rate so that the software accommodates the margin
delay while voltage switching. Hence reduce the default ramp_delay
populated in the descriptors also by 15%.

Signed-off-by: Keerthy <j-keerthy@...com>
---
 drivers/regulator/lp87565-regulator.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/regulator/lp87565-regulator.c b/drivers/regulator/lp87565-regulator.c
index 04a76ec..9ee08d6 100644
--- a/drivers/regulator/lp87565-regulator.c
+++ b/drivers/regulator/lp87565-regulator.c
@@ -95,6 +95,10 @@ static int lp87565_buck_set_ramp_delay(struct regulator_dev *rdev,
 
 	rdev->constraints->ramp_delay = lp87565_buck_ramp_delay[reg];
 
+	/* Conservatively give a 15% margin */
+	rdev->constraints->ramp_delay =
+				rdev->constraints->ramp_delay * 85 / 100;
+
 	return 0;
 }
 
@@ -154,32 +158,32 @@ static const struct lp87565_regulator regulators[] = {
 	LP87565_REGULATOR("BUCK0", LP87565_BUCK_0, "buck0", lp87565_buck_ops,
 			  256, LP87565_REG_BUCK0_VOUT, LP87565_BUCK_VSET,
 			  LP87565_REG_BUCK0_CTRL_1,
-			  LP87565_BUCK_CTRL_1_EN, 3800,
+			  LP87565_BUCK_CTRL_1_EN, 3230,
 			  buck0_1_2_3_ranges, LP87565_REG_BUCK0_CTRL_2),
 	LP87565_REGULATOR("BUCK1", LP87565_BUCK_1, "buck1", lp87565_buck_ops,
 			  256, LP87565_REG_BUCK1_VOUT, LP87565_BUCK_VSET,
 			  LP87565_REG_BUCK1_CTRL_1,
-			  LP87565_BUCK_CTRL_1_EN, 3800,
+			  LP87565_BUCK_CTRL_1_EN, 3230,
 			  buck0_1_2_3_ranges, LP87565_REG_BUCK1_CTRL_2),
 	LP87565_REGULATOR("BUCK2", LP87565_BUCK_2, "buck2", lp87565_buck_ops,
 			  256, LP87565_REG_BUCK2_VOUT, LP87565_BUCK_VSET,
 			  LP87565_REG_BUCK2_CTRL_1,
-			  LP87565_BUCK_CTRL_1_EN, 3800,
+			  LP87565_BUCK_CTRL_1_EN, 3230,
 			  buck0_1_2_3_ranges, LP87565_REG_BUCK2_CTRL_2),
 	LP87565_REGULATOR("BUCK3", LP87565_BUCK_3, "buck3", lp87565_buck_ops,
 			  256, LP87565_REG_BUCK3_VOUT, LP87565_BUCK_VSET,
 			  LP87565_REG_BUCK3_CTRL_1,
-			  LP87565_BUCK_CTRL_1_EN, 3800,
+			  LP87565_BUCK_CTRL_1_EN, 3230,
 			  buck0_1_2_3_ranges, LP87565_REG_BUCK3_CTRL_2),
 	LP87565_REGULATOR("BUCK10", LP87565_BUCK_10, "buck10", lp87565_buck_ops,
 			  256, LP87565_REG_BUCK0_VOUT, LP87565_BUCK_VSET,
 			  LP87565_REG_BUCK0_CTRL_1,
-			  LP87565_BUCK_CTRL_1_EN, 3800,
+			  LP87565_BUCK_CTRL_1_EN, 3230,
 			  buck0_1_2_3_ranges, LP87565_REG_BUCK0_CTRL_2),
 	LP87565_REGULATOR("BUCK23", LP87565_BUCK_23, "buck23", lp87565_buck_ops,
 			  256, LP87565_REG_BUCK2_VOUT, LP87565_BUCK_VSET,
 			  LP87565_REG_BUCK2_CTRL_1,
-			  LP87565_BUCK_CTRL_1_EN, 3800,
+			  LP87565_BUCK_CTRL_1_EN, 3230,
 			  buck0_1_2_3_ranges, LP87565_REG_BUCK2_CTRL_2),
 };
 
-- 
1.9.1