RE: [PATCH v1 1/7] arm64: dts: imx8dxl-evk: Add vpcie3v3aux regulator for PCIe M.2 connector

[Hongxing Zhu]

> -----Original Message-----
> From: Shawn Guo <shawnguo2@xxxxxxxx>
> Sent: 2025年11月11日 15:37
> To: Hongxing Zhu <hongxing.zhu@xxxxxxx>
> Cc: robh@xxxxxxxxxx; krzk+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx;
> shawnguo@xxxxxxxxxx; Frank Li <frank.li@xxxxxxx>;
> s.hauer@xxxxxxxxxxxxxx; festevam@xxxxxxxxx; kernel@xxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v1 1/7] arm64: dts: imx8dxl-evk: Add vpcie3v3aux
> regulator for PCIe M.2 connector
> 
> On Fri, Oct 24, 2025 at 03:31:46PM +0800, Richard Zhu wrote:
> > Refer to PCI Express M.2 Specification r5.1 sec3.1.1 Power Sources and
> > Grounds.
> >
> > PCI Express M.2 Socket 1 utilizes a 3.3 V power source. The voltage
> > source, 3.3 V, is expected to be available during the system’s
> > stand-by/suspend state to support wake event processing on the
> > communications card.
> >
> > Add vpcie3v3aux regulator to let this 3.3 V power source always on for
> > PCIe M.2 Key E connector on i.MX8DXL EVK board.
> >
> > Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> > ---
> >  arch/arm64/boot/dts/freescale/imx8dxl-evk.dts | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm64/boot/dts/freescale/imx8dxl-evk.dts
> > b/arch/arm64/boot/dts/freescale/imx8dxl-evk.dts
> > index 25a77cac6f0b5..7704dba9e37c0 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8dxl-evk.dts
> > +++ b/arch/arm64/boot/dts/freescale/imx8dxl-evk.dts
> > @@ -649,6 +649,7 @@ &pcie0 {
> >  	pinctrl-names = "default";
> >  	reset-gpio = <&lsio_gpio4 0 GPIO_ACTIVE_LOW>;
> >  	vpcie-supply = <&reg_pcieb>;
> > +	vpcie3v3aux-supply = <&reg_pcieb>;
> 
> Is it a documented binding?
Yes, it is. Please refer to what's Rob said below.

"
It is standard because PCIe spec defines them. pci-bus-common.yaml already defines these:

  vpcie12v-supply:
    description: 12v regulator phandle for the slot

  vpcie3v3-supply:
    description: 3.3v regulator phandle for the slot

  vpcie3v3aux-supply:
    description: 3.3v AUX regulator phandle for the slot

Note that these should really be defined in the root port node rather than the host bridge node. We've done the latter because the RP node is often not defined.

Rob
"

Best Regards
Richard Zhu
> 
> Shawn
> 
> >  	status = "okay";
> >  };
> >
> > --
> > 2.37.1
> >