[PATCH v2 1/4] riscv: dts: spacemit: k1-bananapi-f3: Add vcc5v0_sys regulator for Banana Pi F3

[Anand Moon]

Hi Yixun,

On Sat, 9 May 2026 at 17:48, Yixun Lan <dlan at kernel.org> wrote:
>
> Hi Anand,
>
> On 13:06 Fri 08 May     , Anand Moon wrote:
> > Hi Yixun,
> >
> > Thanks for your review comments.
> >
> > On Thu, 7 May 2026 at 08:15, Yixun Lan <dlan at kernel.org> wrote:
> > >
> > > Hi Anand,
> > >
> > > On 10:48 Sat 02 May     , Anand Moon wrote:
> > > > Define the system 5V fixed regulator (vcc5v0_sys) supplied by the
> > > > DC input. As per the schematics, vcc5v0_sys is the input power source
> > > > for the VCC5V0_HUB and 5V_VBUS reglators. Update these regulators
> > > > to correctly reference vcc5v0_sys as their parent (vin-supply).
> > > >
> > > > Cc: Han Gao <gaohan at iscas.ac.cn>
> > > > Cc: Ze Huang <huang.ze at linux.dev>
> > > > Cc: Chukun Pan <amadeus at jmu.edu.cn>
> > > > Signed-off-by: Anand Moon <linux.amoon at gmail.com>
> > > > ---
> > > >  arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts | 12 ++++++++++++
> > > >  1 file changed, 12 insertions(+)
> > > >
> > > > diff --git a/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts b/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts
> > > > index 5790d927b93d..9727ecdd9f6b 100644
> > > > --- a/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts
> > > > +++ b/arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts
> > > > @@ -50,6 +50,16 @@ reg_dc_in: regulator-dc-in-12v {
> > > >               regulator-always-on;
> > > >       };
> > > >
> > > > +     reg_vcc5v0_sys: regulator-vcc5v0-sys {
> > > This will fall into the catogery of "non-controllable & serve no devices"
> > > see similar comment for 'reg_dc_in' which raised by Krzysztof
> > >
> > > https://lore.kernel.org/all/6530526f-59ca-4753-a068-46c62a1a1fed@kernel.org/
> > >
> > > or should I ask, what's the real problem if regulator has no vin-supply?
> >
> > If the device tree is not configured with the correct power source it
> > will affect performance.
> >
> Please elaborate, or provide enough evidence to prove this, because the
> conclusion you gave here contradicts with what Krzysztof pointed out
I don’t have the schematic for that board, so I skipped replying.

Please refer to the POWER TREE diagram, which provides a clear
visualization of the power sources.

This board accepts two primary power sources: a 12 V DC input and USB
Type‑C power.
>From the schematic’s power tree (page 4):

Type‑C → DC_IN→ SY8386J (Uxxx) → PI PMIC

According to the block diagram, the SY8386J regulator IC is
responsible for generating the VCC5V0_SYS rail  VCC4V0_SYS (see page
13).

USBVBUS → SY8386J → VCC5V0_SYS
USBVBUS → SY8386J → VCC4V0_SYS

USBVBUS ( TypeC port) --> DC_IN--> 12V

In this design, the SY8386J operates as a step‑down converter, supplying
both VCC4V0_SYS and VCC5V0_SYS rails and P! PMIC.

SY8386 is a high-efficiency synchronous step-down DC/DC regulator
capable of delivering up to 6A with wide input voltage support and multiple
protection features.
Datasheet [1] https://datasheet4u.com/download_new.php?id=1604744

I have tried to elaborate as clearly as I can.
>
> > > Any probe failure or something bad happen? (besides /sys/../regulator_summay)
> >
> > Not really; the regulator summary just confirms the PMIC used the
> > correct power source.
> > with te device ip blocks.
> >
> then I see it's unnecessary to add this
>
> > Bananapi F3 schematics.
> > [1] https://drive.google.com/file/d/19iLJ5xnCB_oK8VeQjkPGjzAn39WYyylv/view
> > (page 24)
> >
> > Please check the shematics VCC5V0_SYS page 4
> > VCC5V0_SYS->USB_VCC5V0->HDMI_VCC5V0->FAN_VCC5V0->VCC3V3_SYS
> >
> > Please check the shematics VCC5V0_SYS page 24
> > VCC5V0_SYS input for VCC5V0_HUB and 5V_VBUS give the USB hub,
> > which is enabled by USB3_PWREN (gpio pin)>
> >
> > Plese check power tree page 4
> > USBVBUS->SY8386J UXXX -> PCIE_VCC3V3 for pcie vin source
> >
> > So, this series tries to fix the vin source for USB 3.0 and PCIe nodes.
> >
> This is not what I ask..
Opps, I tried, but I wasn’t able to clearly elaborate on how the power sources
are distributed across the various peripherals.
>
> --
> Yixun Lan (dlan)
Thanks
-Anand