Re: [linux-sunxi] Re: [PATCH] regulator: axp20x: Add support for the (external) drivebus regulator

[Hans de Goede]

Hi,

On 16-05-16 19:06, Chen-Yu Tsai wrote:
> Hi,
>
> On Sun, May 15, 2016 at 1:55 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> > The axp20x pmics have 2 power inputs, one called ACIN which is intended
> > for to be supplied via a powerbarrel on the board and one called VBUS
> > which is intended to be supplied via an otg connector.
> >
> > In the VBUS case the pmic needs to know if the board is supplying power
> > to the otg connector, because then it should not take any power from
> > its VBUS pin. The axp209 pmic has a N_VBUSEN input pin via which the
> > board can signal to the pmic whether the board is supplying power to the
> > otg connector or not.
> >
> > On the axp221/axp223 this pin can alternatively be used as an output
> > which controls an external regulator which (optionally) supplies
> > power to the otg connector from the board. When the pin is used as
> > output it is called DRIVEBUS in the datasheet.
>
> The datasheet actually calls it DRIVEVBUS. DRIVEBUS seems to be some
> typo Allwinner has in their code.

Fixed for v2.

> > This commit adds support for the DRIVEBUS pin as an extra pmic
> > controlled regulator. Since this is optional a new x-powers,drivebus dt
> > property is added. When this is present the misc-control register is
> > written to change the N_VBUSEN input pin to DRIVEBUS output pin mode and
> > the extra drivebus regulator is registered with the regulator subsystem.
> >
> > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > ---
> >  Documentation/devicetree/bindings/mfd/axp20x.txt |  5 ++++
> >  drivers/regulator/axp20x-regulator.c             | 30 ++++++++++++++++++++++++
> >  2 files changed, 35 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/mfd/axp20x.txt b/Documentation/devicetree/bindings/mfd/axp20x.txt
> > index d20b103..7a88479 100644
> > --- a/Documentation/devicetree/bindings/mfd/axp20x.txt
> > +++ b/Documentation/devicetree/bindings/mfd/axp20x.txt
> > @@ -22,6 +22,11 @@ Optional properties:
> >                       AXP152/20X: range:  750-1875, Default: 1.5 MHz
> >                       AXP22X/80X: range: 1800-4050, Default: 3   MHz
> >
> > +- x-powers,drivebus: axp221 / axp223 only boolean, set this when the N_VBUSEN
> > +                  pin is used as an output pin to control an external regulator
> > +                  to drive the OTG VBus, rather then as an input pin which
> > +                  signals whether the board is driving OTG VBus or not.
> > +
>
> You should also add it to the regulators table further down in the binding.
> And, as Rob mentioned, x-powers,drive-vbus-en (or drivevbus-en) is better
> for a boolean property.

Both fixed for v2.

> >  - <input>-supply: a phandle to the regulator supply node. May be omitted if
> >                   inputs are unregulated, such as using the IPSOUT output
> >                   from the PMIC.
> > diff --git a/drivers/regulator/axp20x-regulator.c b/drivers/regulator/axp20x-regulator.c
> > index 514a5e8..2422ddd 100644
> > --- a/drivers/regulator/axp20x-regulator.c
> > +++ b/drivers/regulator/axp20x-regulator.c
> > @@ -36,6 +36,8 @@
> >
> >  #define AXP20X_FREQ_DCDC_MASK          0x0f
> >
> > +#define AXP22X_MISC_N_VBUSEN_FUNC      BIT(4)
> > +
> >  #define AXP_DESC_IO(_family, _id, _match, _supply, _min, _max, _step, _vreg,   \
> >                     _vmask, _ereg, _emask, _enable_val, _disable_val)           \
> >         [_family##_##_id] = {                                                   \
> > @@ -230,6 +232,18 @@ static const struct regulator_desc axp22x_regulators[] = {
> >         AXP_DESC_FIXED(AXP22X, RTC_LDO, "rtc_ldo", "ips", 3000),
> >  };
> >
> > +static const struct regulator_desc axp22x_drivebus_regulator = {
> > +       .name           = "drivebus",
> > +       .supply_name    = "ips",
>
> Given that you are approximating a gpio (in this case, the
> N_VBUSEN/DRIVEVBUS pin)
> controlled fixed voltage regulator, it would be better if you could:
>
> a) have some way to specify the output voltage, so it looks like a fixed voltage
>    regulator that can be turned on/off.

This is fixed by your suggestion b) actually, if no get_voltage* ops are specified,
it will inherit the voltage of it supply.

> And
>
> b) have a separate supply name for this so it properly propagates enable/disable
>    calls. It would also pass the upstream voltage, thus behaving like a switch
>    you intended with the axp20x_ops_sw below.

Ack, fixed for v2.

Thanks for the review.

Regards,

Hans