Hi Richard, Am Montag, dem 22.03.2021 um 09:06 +0000 schrieb Richard Zhu: > > -----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? The regulator API doesn't care, you can call enable/disable in the driver as normal. If the regulator is marked as always-on it will just stay enabled even if the use-count drops to 0. The other question however is if it's even allowed by the SoC design to disable this supply outside of deep power down. A quick look into the reference manual and datasheet didn't yield any information about this. Regards, Lucas
