On Thu, 21 Dec 2023 10:20:49 +0800
fuyao <fuyao@xxxxxxxxxx> wrote:
Hi,
thanks for the reply!
> On Wed, Dec 20, 2023 at 03:04:00PM +0000, Andre Przywara wrote:
> > On Wed, 20 Dec 2023 16:18:43 +0800
> > fuyao <fuyao1697@xxxxxxx> wrote:
> >
> > Hi,
> >
> > > the aldo1 is connect regulator pin which power the TV.
> >
> > What do you mean with that? That ALDO1 is connected to VCC-TVOUT and/or
> > VCC-TVIN on the R40 SoC?
>
> The ALDO1 is connected to VCC-TVOUT on the R40 Soc.
Ah, thanks for the confirmation.
> > > The USB core use TV ref as reference Voltage.
> >
> > The USB core in the SoC? So pin VCC-USB, which requires 3.3V, the same
> > voltage as the TV pins?
> > Which means this doesn't really have much to do with TV, it's just that
> > USB and also "TV" are supplied by ALDO1?
>
> The internal USB PHY requires a reference voltage. It seems that in
> order to save costs, the reference voltage of the TVOUT module is used.
Do you mean a USB *reference* voltage that is separate from the USB PHY
power supply voltage, so pin VCC-USB on the SoC? And that it is internally
connected to some TV-OUT related circuits? So that would apply to all
devices using the R40 SoC then?
Or is it simply that the SoC pins VCC-TVOUT and VCC-USB are connected
together, on this SoM?
Do you have access to some schematic? I couldn't find one online easily,
so cannot check this myself.
Thanks,
Andre
> > > Signed-off-by: fuyao <fuyao1697@xxxxxxx>
> > > ---
> > > arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi | 7 +++++++
> > > 1 file changed, 7 insertions(+)
> > >
> > > diff --git a/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi b/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi
> > > index 9f39b5a2bb35..8906170461df 100644
> > > --- a/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi
> > > +++ b/arch/arm/boot/dts/allwinner/sun8i-r40-feta40i.dtsi
> > > @@ -42,6 +42,13 @@ &pio {
> > > vcc-pg-supply = <®_dldo1>;
> > > };
> > >
> > > +®_aldo1 {
> > > + regulator-always-on;
> >
> > So did USB never work before, with the DT as in mainline?
> >
>
> The USB can work, but is unstable. Occasionally disconnected because of
> the D+/D- electrical characteristics.
>
> > For always-on regulators it would be good to see some rationale why this
> > cannot be referenced by its consumer. If it is really supplying the USB
> > core, that would be a reason, because we don't have a good way of
> > describing this.
> >
> > > + regulator-min-microvolt = <3300000>;
> > > + regulator-max-microvolt = <3300000>;
> > > + regulator-name = "vcc-aldo1";
> >
> > Regulators should be named after their users, so use something like:
> > regulator-name = "vcc-3v3-tv-usb";
> >
>
> thanks.
>
> > That then also serves as documentation of why this is always on.
> >
> > Cheers,
> > Andre
> >
> > > +};
> > > +
> > > ®_aldo2 {
> > > regulator-always-on;
> > > regulator-min-microvolt = <1800000>;
> >
>
