On Wed, Dec 12, 2018 at 12:14:57AM +1100, Julian Calaby wrote:
> Hi Priit and Olliver,
>
> On Tue, Dec 11, 2018 at 5:42 AM Priit Laes <plaes@xxxxxxxxx> wrote:
> >
> > From: Olliver Schinagl <oliver@xxxxxxxxxxx>
> >
> > The AXP209 supports ramping up voltages on several regulators such as
> > DCDC2 and LDO3.
> >
> > This patch adds preliminary support for the regulator-ramp-delay property
> > for these 2 regulators. Note that the voltage ramp only works when
> > regulator is already enabled. E.g. when going from say 0.7 V to 3.6 V.
> >
> > When turning on the regulator, no voltage ramp is performed in hardware.
> >
> > What this means, is that if the bootloader brings up the voltage at 0.7 V,
> > the ramp delay property is properly applied. If however, the bootloader
> > leaves the power off, no ramp delay is applied when the power is
> > enabled by the regulator framework.
> >
> > Signed-off-by: Olliver Schinagl <oliver@xxxxxxxxxxx>
> > Signed-off-by: Priit Laes <plaes@xxxxxxxxx>
> > ---
> > drivers/regulator/axp20x-regulator.c | 85 +++++++++++++++++++++++++++++-
> > 1 file changed, 85 insertions(+)
> >
> > diff --git a/drivers/regulator/axp20x-regulator.c b/drivers/regulator/axp20x-regulator.c
> > index 9a2db28..1d9fa62 100644
> > --- a/drivers/regulator/axp20x-regulator.c
> > +++ b/drivers/regulator/axp20x-regulator.c
> > @@ -346,6 +357,79 @@
> > .ops = &axp20x_ops_range, \
> > }
> >
> > +static const int axp209_dcdc2_ldo3_slew_rates[] = {
> > + 1600,
> > + 800,
> > +};
> > +
> > +static int axp20x_set_ramp_delay(struct regulator_dev *rdev, int ramp)
> > +{
> > + struct axp20x_dev *axp20x = rdev_get_drvdata(rdev);
> > + const struct regulator_desc *desc = rdev->desc;
> > + u8 reg, mask, enable, cfg = 0xff;
> > + const int *slew_rates;
> > + int rate_count = 0;
> > +
> > + if (!rdev)
> > + return -EINVAL;
> > +
> > + switch (axp20x->variant) {
> > + case AXP209_ID:
> > + if (desc->id == AXP20X_DCDC2) {
>
> Is slew_rates supposed to be set here?
Yes, nice catch.
>
> > + rate_count = ARRAY_SIZE(axp209_dcdc2_ldo3_slew_rates);
> > + reg = AXP20X_DCDC2_LDO3_V_RAMP;
> > + mask = AXP20X_DCDC2_LDO3_V_RAMP_DCDC2_RATE_MASK |
> > + AXP20X_DCDC2_LDO3_V_RAMP_DCDC2_EN_MASK;
> > + enable = (ramp > 0) ?
> > + AXP20X_DCDC2_LDO3_V_RAMP_DCDC2_EN :
> > + !AXP20X_DCDC2_LDO3_V_RAMP_DCDC2_EN;
> > + break;
> > + }
> > +
> > + if (desc->id == AXP20X_LDO3) {
> > + slew_rates = axp209_dcdc2_ldo3_slew_rates;
> > + rate_count = ARRAY_SIZE(axp209_dcdc2_ldo3_slew_rates);
> > + reg = AXP20X_DCDC2_LDO3_V_RAMP;
> > + mask = AXP20X_DCDC2_LDO3_V_RAMP_LDO3_RATE_MASK |
> > + AXP20X_DCDC2_LDO3_V_RAMP_LDO3_EN_MASK;
> > + enable = (ramp > 0) ?
> > + AXP20X_DCDC2_LDO3_V_RAMP_LDO3_EN :
> > + !AXP20X_DCDC2_LDO3_V_RAMP_LDO3_EN;
> > + break;
> > + }
> > +
> > + if (rate_count > 0)
> > + break;
>
> You could save one to two tests by combining the above three if statements, i.e.
>
> if (DCDC2) {
> // set DCDC2 stuff
>
> break;
> } else if (LDO3) {
> // set LDO3 stuff
>
> break;
> }
OK, will look into it.
>
> As written, the rate_count > 0 test will never be true as every block
> that sets rate_count breaks out of the switch block.
Yes, it is somewhat superfluous, as each regulator which supports ramping
should break out of the switch itself.
> You could then calculate rate_count below the switch block.
>
> > +
> > + /* fall through */
> > + default:
> > + /* Not supported for this regulator */
> > + return -ENOTSUPP;
> > + }
> > +
> > + if (ramp == 0) {
> > + cfg = enable;
> > + } else {
> > + int i;
> > +
> > + for (i = 0; i < rate_count; i++) {
> > + if (ramp <= slew_rates[i])
> > + cfg = AXP20X_DCDC2_LDO3_V_RAMP_LDO3_RATE(i);
> > + else
> > + break;
> > + }
> > +
> > + if (cfg == 0xff) {
> > + dev_err(axp20x->dev, "unsupported ramp value %d", ramp);
> > + return -EINVAL;
> > + }
> > +
> > + cfg |= enable;
> > + }
> > +
> > + return regmap_update_bits(axp20x->regmap, reg, mask, cfg);
> > +}
> > +
>
>
>
> --
> Julian Calaby
>
> Email: julian.calaby@xxxxxxxxx
> Profile: http://www.google.com/profiles/julian.calaby/
