> -----Original Message----- > From: Lucas Stach <l.stach@xxxxxxxxxxxxxx> > Sent: Friday, March 19, 2021 5:49 PM > To: Richard Zhu <hongxing.zhu@xxxxxxx>; andrew.smirnov@xxxxxxxxx; > shawnguo@xxxxxxxxxx; kw@xxxxxxxxx; bhelgaas@xxxxxxxxxx; > stefan@xxxxxxxx; lorenzo.pieralisi@xxxxxxx > Cc: linux-pci@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx>; > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > kernel@xxxxxxxxxxxxxx > Subject: [EXT] Re: [PATCH 1/3] dt-bindings: imx6q-pcie: specify the imx8mq > pcie phy voltage > Am Freitag, dem 19.03.2021 um 16:24 +0800 schrieb Richard Zhu: > > Both 1.8v and 3.3v power supplies can be feeded to i.MX8MQ PCIe PHY. > > In default, the PCIE_VPH voltage is suggested to be 1.8v refer to data > > sheet. When PCIE_VPH is supplied by 3.3v in the HW schematic design, > > the VREG_BYPASS bits of GPR registers should be cleared from default > > value 1b'1 to 1b'0. > > > > Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx> > > --- > > Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt > > b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt > > index de4b2baf91e8..23efbad9e804 100644 > > --- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt > > +++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt > > @@ -59,6 +59,10 @@ Additional required properties for imx7d-pcie and > imx8mq-pcie: > > Additional required properties for imx8mq-pcie: > > - clock-names: Must include the following additional entries: > > - "pcie_aux" > > +- pcie-vph-3v3: If present then PCIE_VPH is feeded by 3.3v in the HW > > + schematic design. The PCIE_VPH is suggested to be 1.8v refer to the > > + data sheet. If the PCIE_VPH is supplied by 3.3V, the VREG_BYPASS > > + should be cleared to zero accordingly. > > Uhm, no. Please don't add boolean DT properties for random parts of the > board design. > > If we need to know the voltage of PCIE_VPH, we should really add the VPH > regulator as a supply to the PCIe controller node, then work out the voltage > the usual way by using the Linux regulator API. > [Richard Zhu] Hi Lucas: Thanks for your comments. Since the vgen5_reg is used to power up PCIe PHY on i.MX8MQ EVK board, and it's set to be "regulator-always-on;". Did only the regulator_get_voltage or combined with regulator_enable/regulator_disable can be used in the driver? Best Regards Richard Zhu > Regards, > Lucas
