On Mon, Nov 26, 2018 at 05:27:47PM +0200, Priit Laes wrote: > From: Olliver Schinagl <[email protected]> > > In the past, there have been words on various lists that if LDO3 is > disabled in u-boot, but enabled in the DTS, the axp209 driver would > fail to continue/hang. Several enable/disable patches have been > issues to devicetree's in both the kernel and u-boot to address > this issue. > > What really happened however, was that the AXP209 shuts down without > a notice and without setting an interrupt. This is caused when LDO3 > gets overloaded, for example with large capacitors on the LDO3 output. > > Normally, we would expect that AXP209 would source 200 mA as per > datasheet and set and trigger an interrupt when being overloaded. > For some reason however, this does not happen. > > As a work-around, we use the soft-start constraint of the regulator > node to first bring up the LDO3 to the lowest possible voltage and > then enable the LDO. After that, we can set the requested voltage > as usual. > > Combining this setting with the regulator-ramp-delay allows LDO3 to > enable voltage slowly and staggered, potentially reducing overall > inrush current. > > Signed-off-by: Olliver Schinagl <[email protected]> > Signed-off-by: Priit Laes <[email protected]> > --- > drivers/regulator/axp20x-regulator.c | 57 ++++++++++++++++++++++++++++- > 1 file changed, 56 insertions(+), 1 deletion(-) > > diff --git a/drivers/regulator/axp20x-regulator.c > b/drivers/regulator/axp20x-regulator.c > index 1d9fa62..e8a895b 100644 > --- a/drivers/regulator/axp20x-regulator.c > +++ b/drivers/regulator/axp20x-regulator.c > @@ -14,6 +14,7 @@ > */ > > #include <linux/bitops.h> > +#include <linux/delay.h> > #include <linux/err.h> > #include <linux/init.h> > #include <linux/mfd/axp20x.h> > @@ -23,6 +24,7 @@ > #include <linux/platform_device.h> > #include <linux/regmap.h> > #include <linux/regulator/driver.h> > +#include <linux/regulator/machine.h> > #include <linux/regulator/of_regulator.h> > > #define AXP20X_GPIO0_FUNC_MASK GENMASK(3, 0) > @@ -430,6 +432,59 @@ static int axp20x_set_ramp_delay(struct regulator_dev > *rdev, int ramp) > return regmap_update_bits(axp20x->regmap, reg, mask, cfg); > } > > +static int axp20x_regulator_enable_regmap(struct regulator_dev *rdev) > +{ > + struct axp20x_dev *axp20x = rdev_get_drvdata(rdev); > + const struct regulator_desc *desc = rdev->desc; > + > + if (!rdev) > + return -EINVAL; > + > + switch (axp20x->variant) { > + case AXP209_ID: > + if ((desc->id == AXP20X_LDO3) && > + rdev->constraints && rdev->constraints->soft_start) { > + int v_out; > + int ret; > + > + /* > + * On some boards, the LDO3 can be overloaded when > + * turning on, causing the entire PMIC to shutdown > + * without warning. Turning it on at the minimal voltage > + * and then setting the voltage to the requested value > + * works reliably. > + */ > + if (regulator_is_enabled_regmap(rdev)) > + break; > + > + v_out = regulator_get_voltage_sel_regmap(rdev); > + if (v_out < 0) > + return v_out; > + > + if (v_out == 0) > + break; > + > + ret = regulator_set_voltage_sel_regmap(rdev, 0x00); > + /* > + * A small pause is needed between > + * setting the voltage and enabling the LDO to give the > + * internal state machine time to process the request. > + */ > + usleep_range(1000, 5000); > + ret |= regulator_enable_regmap(rdev); > + ret |= regulator_set_voltage_sel_regmap(rdev, v_out); > + > + return ret; > + } > + break; > + default: > + /* No quirks */ > + break; > + } > + > + return regulator_enable_regmap(rdev); > +}; > +
This is some pretty generic code, and could be useful to some other users. I guess a generic function would be better for this. Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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