Re: [RFCv1 2/3] ARM: dts: meson8b: odroidc1: fix USB power supplies for phy

[Martin Blumenstingl <martin.blumenstingl@googlemail.com>]

Hi Anand,

On Mon, Feb 4, 2019 at 9:03 PM Anand Moon <linux.amoon@gmail.com> wrote:
>
> Hi Martin,
>
> Thanks for your comments.
> Please find my comments below.
>
> On Mon, 4 Feb 2019 at 18:59, Martin Blumenstingl
> <martin.blumenstingl@googlemail.com> wrote:
> >
> > Hi Anand,
> >
> > On Wed, Jan 23, 2019 at 4:12 PM Anand Moon <linux.amoon@gmail.com> wrote:
> > >
> > > This patch enables the USB Host controller (USB0) and the relative USB0 PHY.
> > > From the shematics GPIOAO.BIT5 gpio input for the PWREN signal of the
> > > USB_OTG controller (usb0) which is also linked to USB_HOST controller (usb1).
> > > Add missing phy-supply link to both  USB0 and USB1 phy controller
> > > This changes fixed the power issue on usb ports. Changes help fix usb reset warning.
> > I prefer to change the way patches 2 and 3 are split:
> > - this one should only add the regulators and link it with the USB controller
> > - patch 3 should enable usb0 and usb0_phy
> >
> > the reason behind this is the "Fixes" tag below. it's good to have it,
> > so please keep it in this patch!
> > however, enabling usb0 is not a fix for a commit which enables the
> > "USB host controller on Odroid-C1/C1+" (which is why enabling usb0 and
> > usb0_phy should be part of patch 3)
> >
>
> Ok I will split this changes as per your suggestion.
thank you!

> > > [  821.991470] usb 1-1.2: reset high-speed USB device number 3 using dwc2
> > > [  825.243385] usb 1-1.2: reset high-speed USB device number 3 using dwc2
> > > [  828.151310] usb 1-1.2: reset high-speed USB device number 3 using dwc2
> > > [  830.991241] usb 1-1.2: reset high-speed USB device number 3 using dwc2
> > >
> > > Fixes: 2eb79a4d15ff ("ARM: dts: meson: enabling the USB Host controller on Odroid-C1/C1+ board")
> > > Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> > > Cc: Jerome Brunet <jbrunet@baylibre.com>
> > > Cc: Neil Armstrong <narmstrong@baylibre.com>
> > > Cc: Kevin Hilman <khilman@baylibre.com>
> > > Signed-off-by: Anand Moon <linux.amoon@gmail.com>
> > > ---
> > > Changes from previous patch.
> > >
> > > Fix the subject and commit message as per Martin's request
> > >  --Add the signal name in the comment
> > >  --Replace vbus-supply with phy-supply linking the power supply to phy node as pointed by Marine
> > >    which a PWREN signal in the USB_HOST controller (usb1)
> > >
> > > USB_VBUS                      4    2      0 unknown  5000mV     0mA  5000mV  5000mV
> > >    phy-c1108820.phy.1         2                                 0mA     0mV     0mV
> > >    phy-c1108800.phy.0         2                                 0mA     0mV     0mV
> > > ---
> > >  arch/arm/boot/dts/meson8b-odroidc1.dts | 26 ++++++++++++++++++++++++++
> > >  1 file changed, 26 insertions(+)
> > >
> > > diff --git a/arch/arm/boot/dts/meson8b-odroidc1.dts b/arch/arm/boot/dts/meson8b-odroidc1.dts
> > > index 58669abda259..bfa472a679d9 100644
> > > --- a/arch/arm/boot/dts/meson8b-odroidc1.dts
> > > +++ b/arch/arm/boot/dts/meson8b-odroidc1.dts
> > > @@ -83,6 +83,22 @@
> > >                 regulator-max-microvolt = <5000000>;
> > >         };
> > >
> > > +       usb_vbus: regulator-usb-vbus {
> > > +               compatible = "regulator-fixed";
> > > +
> > > +               regulator-name = "USB_VBUS";
> > > +               regulator-min-microvolt = <5000000>;
> > > +               regulator-max-microvolt = <5000000>;
> > > +
> > > +               vin-supply = <&p5v0>;
> > > +
> > > +               /*
> > > +                * signal name from schematics: PWREN
> > > +                */
> > > +               gpio = <&gpio_ao GPIOAO_5 GPIO_ACTIVE_HIGH>;
> > > +               enable-active-high;
> > > +       };
> > > +
> > >         tflash_vdd: regulator-tflash_vdd {
> > >                 /*
> > >                  * signal name from schematics: TFLASH_VDD_EN
> > > @@ -295,8 +311,18 @@
> > >         pinctrl-names = "default";
> > >  };
> > >
> > > +&usb0_phy {
> > > +       status = "okay";
> > > +       phy-supply = <&usb_vbus>;
> > I'm not sure whether phy-supply is correct here
> > with the PHY framework and the dwc2 controller regulators can be set as:
> > - phy-supply (inside the PHY node)
> > - vbus-supply (inside the dwc2 controller node)
> >
> > phy-supply is always enabled when the PHY is enabled.
> > vbus-supply is smarter: it's enabled whenever the controller is in
> > host mode (or OTG detects hosts mode), but disabled in
> > device/peripheral mode
> >
> phy-supply enables the power per port power setting which get on when
> device is connected.
the actual dt-bindings description is "a regulator that provides power
to the PHY", see [0]
(note that it states that it powers the PHY, not the bus or any
connected device)

> vbus-supply controls the D+ D- signal during high seed data transfer.
I believe this is not the case. the vbus-supply seems undocumented at the moment

however, the dwc2 driver has separate supplies for vusb_a (analog) and
vusb_d (digital), see [1] (these are used here: [2])

VBUS (in my own words) is the +5V power signal which is provided by
the USB host to power the USB device.

my interpretationfor the Amlogic SoCs is:
- vusb_a and vusb_d are generated internally, not sure if there's an
external fixed regulator
- there is no phy-supply (the PHY itself is powered by clock-gating
using the CLKID_USB clock)
- usb0 VBUS is controlled by GPIOAO_5


Regards
Martin


[0] https://elixir.bootlin.com/linux/v5.0-rc5/source/Documentation/devicetree/bindings/phy/phy-bindings.txt
[1] https://elixir.bootlin.com/linux/v5.0-rc5/source/drivers/usb/dwc2/core.h#L72
[2] https://elixir.bootlin.com/linux/v5.0-rc5/source/drivers/usb/dwc2/platform.c#L293