Both 1.8v and 3.3v power supplies can be used by 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. Thus, the internal 3v3 to 1v8 translator would be
turned on.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
---
 Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
index de4b2baf91e8..e6d1886144ce 100644
--- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
+++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt

@@ -38,6 +38,9 @@ Optional properties:

   The regulator will be enabled when initializing the PCIe host and
   disabled either as part of the init process or when shutting down the
   host.
+- vph-supply: Should specify the regulator in charge of VPH one of the three
+  PCIe PHY powers. This regulator can be supplied by both 1.8v and 3.3v voltage
+  supplies. Might be used to distinguish different HW board designs.