Re: [PATCH 7/9] dt-bindings: connector: Add PCIe M.2 Mechanical Key E connector

[Rob Herring <robh@kernel.org>]

On Thu, Nov 13, 2025 at 10:30:42AM +0530, Manivannan Sadhasivam wrote:
> On Wed, Nov 12, 2025 at 12:11:56PM -0500, Frank Li wrote:
> > On Wed, Nov 12, 2025 at 08:15:19PM +0530, Manivannan Sadhasivam wrote:
> > > Add the devicetree binding for PCIe M.2 Mechanical Key E connector defined
> > > in the PCI Express M.2 Specification, r4.0, sec 5.1.2. This connector
> > > provides interfaces like PCIe or SDIO to attach the WiFi devices to the
> > > host machine, USB or UART+PCM interfaces to attach the Bluetooth (BT)
> > > devices along with additional interfaces like I2C for NFC solution. At any
> > > point of time, the connector can only support either PCIe or SDIO as the
> > > WiFi interface and USB or UART as the BT interface.
> > >
> > > The connector provides a primary power supply of 3.3v, along with an
> > > optional 1.8v VIO supply for the Adapter I/O buffer circuitry operating at
> > > 1.8v sideband signaling.
> > >
> > > The connector also supplies optional signals in the form of GPIOs for fine
> > > grained power management.
> > >
> > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> > > ---
> > >  .../bindings/connector/pcie-m2-e-connector.yaml    | 154 +++++++++++++++++++++
> > >  MAINTAINERS                                        |   1 +
> > >  2 files changed, 155 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/connector/pcie-m2-e-connector.yaml b/Documentation/devicetree/bindings/connector/pcie-m2-e-connector.yaml
> > > new file mode 100644
> > > index 0000000000000000000000000000000000000000..91cb56b1a75b7e3de3b9fe9a7537089f96875746
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/connector/pcie-m2-e-connector.yaml
> > > @@ -0,0 +1,154 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/connector/pcie-m2-e-connector.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: PCIe M.2 Mechanical Key E Connector
> > > +
> > > +maintainers:
> > > +  - Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
> > > +
> > > +description:
> > > +  A PCIe M.2 E connector node represents a physical PCIe M.2 Mechanical Key E
> > > +  connector. Mechanical Key E connectors are used to connect Wireless
> > > +  Connectivity devices including combinations of Wi-Fi, BT, NFC to the host
> > > +  machine over interfaces like PCIe/SDIO, USB/UART+PCM, and I2C.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: pcie-m2-e-connector
> > > +
> > > +  vpcie3v3-supply:
> > > +    description: A phandle to the regulator for 3.3v supply.
> > > +
> > > +  vpcie1v8-supply:
> > > +    description: A phandle to the regulator for VIO 1.8v supply.
> > > +
> > > +  ports:
> > > +    $ref: /schemas/graph.yaml#/properties/ports
> > > +    description: OF graph bindings modeling the interfaces exposed on the
> > > +      connector. Since a single connector can have multiple interfaces, every
> > > +      interface has an assigned OF graph port number as described below.
> > > +
> > > +    properties:
> > > +      port@0:
> > > +        $ref: /schemas/graph.yaml#/properties/port
> > > +        description: PCIe/SDIO interface
> > 
> > 
> > PCIe and SDIO is difference signal at key E. why combine to one port? The
> > similar case is USB2.0/UART
> > 
> 
> They will be defined as separate endpoints in the next version.
> 
> > > +
> > > +      port@1:
> > > +        $ref: /schemas/graph.yaml#/properties/port
> > > +        description: USB 2.0/UART interface
> > > +
> > > +      port@2:
> > > +        $ref: /schemas/graph.yaml#/properties/port
> > > +        description: PCM/I2S interface
> > > +
> > > +      port@3:
> > > +        $ref: /schemas/graph.yaml#/properties/port
> > > +        description: I2C interface
> > > +
> > > +    oneOf:
> > > +      - required:
> > > +          - port@0
> > > +
> > > +  clocks:
> > > +    description: 32.768 KHz Suspend Clock (SUSCLK) input from the host system to
> > > +      the M.2 card. Refer, PCI Express M.2 Specification r4.0, sec 3.1.12.1 for
> > > +      more details.
> > > +    maxItems: 1
> > 
> > Do we need add pciref clock here?
> > 
> > > +
> > > +  w_disable1-gpios:
> > 
> > use "-"
> > 
> > w-disable1-gpios
> > 
> 
> I just went with the spec that defines the signal as W_DISABLE.
> 
> > > +    description: GPIO controlled connection to W_DISABLE1# signal. This signal
> > > +      is used by the system to disable WiFi radio in the M.2 card. Refer, PCI
> > > +      Express M.2 Specification r4.0, sec 3.1.12.3 for more details.
> > > +    maxItems: 1
> > > +
> > > +  w_disable2-gpios:
> > > +    description: GPIO controlled connection to W_DISABLE2# signal. This signal
> > > +      is used by the system to disable BT radio in the M.2 card. Refer, PCI
> > > +      Express M.2 Specification r4.0, sec 3.1.12.3 for more details.
> > > +    maxItems: 1
> > > +
> > > +  led1-gpios:
> > > +    description: GPIO controlled connection to LED_1# signal. This signal is
> > > +      used by the M.2 card to indicate the card status via the system mounted
> > > +      LED. Refer, PCI Express M.2 Specification r4.0, sec 3.1.12.2 for more
> > > +      details.
> > > +    maxItems: 1
> > > +
> > > +  led2-gpios:
> > > +    description: GPIO controlled connection to LED_2# signal. This signal is
> > > +      used by the M.2 card to indicate the card status via the system mounted
> > > +      LED. Refer, PCI Express M.2 Specification r4.0, sec 3.1.12.2 for more
> > > +      details.
> > > +    maxItems: 1
> > > +
> > > +  viocfg-gpios:
> > > +    description: GPIO controlled connection to IO voltage configuration
> > > +      (VIO_CFG) signal. This signal is used by the M.2 card to indicate to the
> > > +      host system that the card supports an independent IO voltage domain for
> > > +      the sideband signals. Refer, PCI Express M.2 Specification r4.0, sec
> > > +      3.1.15.1 for more details.
> > > +    maxItems: 1
> > > +
> > > +  uim_power_src-gpios:
> > 
> > property use -
> > 
> 
> Again, this is as per the spec. If DT maintainers object to it, I'll change it.

Use '-'.

Rob