Commit c5a4655d authored by MyungJoo Ham's avatar MyungJoo Ham Committed by Liam Girdwood
Browse files

regulator: MAX8998: set_voltage bugfix. ramp_up delay and min/max voltage 



Two issues are addressed for max8998_set_voltage function.

1. Min/Max Voltage.

	max8998_set_voltage had been using the voltage value of

	min ( voltage[i] >= max_vol , i )

	This is corrected to use:

	min ( voltage[i] >= min_vol , i )

2. Ramp Up Delay.

	max8998_set_voltage should provide delay for BUCK1/2
if ENRAMP is on. It reads RAMP value from ONOFF4 register to determine
RAMP delay length. However, when max8998_set_voltage's new voltage is
lower than the previous, we don't care because it does not deteriorate
the stability.

Changes since v1:
- rebased onto latest regulator-for-next tree

Signed-off-by: default avatarMyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: default avatarKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Acked-by: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: default avatarLiam Girdwood <lrg@slimlogic.co.uk>
parent c789ca20

drivers/regulator/max8998.c

+27 −2
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/slab.h>

#include <linux/interrupt.h>

#include <linux/mutex.h>

#include <linux/delay.h>

#include <linux/platform_device.h>

#include <linux/regulator/driver.h>

#include <linux/mfd/max8998.h>
@@ -297,10 +298,13 @@ static int max8998_set_voltage(struct regulator_dev *rdev, 
{

	struct max8998_data *max8998 = rdev_get_drvdata(rdev);

	int min_vol = min_uV / 1000, max_vol = max_uV / 1000;

	int previous_vol = 0;

	const struct voltage_map_desc *desc;

	int ldo = max8998_get_ldo(rdev);

	int reg, shift = 0, mask, ret;

	int i = 0;

	u8 val;

	bool en_ramp = false;



	if (ldo > ARRAY_SIZE(ldo_voltage_map))

		return -EINVAL;
@@ -312,15 +316,36 @@ static int max8998_set_voltage(struct regulator_dev *rdev, 
	if (max_vol < desc->min || min_vol > desc->max)

		return -EINVAL;



	while (desc->min + desc->step*i < max_vol &&

	while (desc->min + desc->step*i < min_vol &&

	       desc->min + desc->step*i < desc->max)

		i++;



	if (desc->min + desc->step*i > max_vol)

		return -EINVAL;



	ret = max8998_get_voltage_register(rdev, &reg, &shift, &mask);

	if (ret)

		return ret;



	return max8998_update_reg(max8998->iodev, reg, i<<shift, mask<<shift);

	/* wait for RAMP_UP_DELAY if rdev is BUCK1/2 and

	 * ENRAMP is ON */

	if (ldo == MAX8998_BUCK1 || ldo == MAX8998_BUCK2) {

		max8998_read_reg(max8998->iodev, MAX8998_REG_ONOFF4, &val);

		if (val & (1 << 4)) {

			en_ramp = true;

			previous_vol = max8998_get_voltage(rdev);

		}

	}



	ret = max8998_update_reg(max8998->iodev, reg, i<<shift, mask<<shift);



	if (en_ramp == true) {

		int difference = desc->min + desc->step*i - previous_vol/1000;

		if (difference > 0)

			udelay(difference / ((val & 0x0f) + 1));

	}



	return ret;

}



static struct regulator_ops max8998_ldo_ops = {

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