> -----Original Message----- > From: Lucas Stach <l.stach@xxxxxxxxxxxxxx> > Sent: Monday, March 22, 2021 8:15 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: Re: [PATCH 1/3] dt-bindings: imx6q-pcie: specify the > imx8mq pcie phy voltage > 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: 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. [Richard Zhu] Hi Lucas: Yes it is. The PCIe PHY power down manipulations are not described in the RM document. How about to get voltage here only currently, and the regulator enable/disable operations would be added further if these enable/disable operations are possible and required later? Best Regards Richard > > Regards, > Lucas
