linux-kernel - RE: [RFC PATCH v2 1/2] dt-bindings: phy: Document cadence Sierra PHY bindings

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Date:   Thu, 27 Sep 2018 10:32:12 +0000
From:   Alan Douglas <adouglas@...ence.com>
To:     Rob Herring <robh@...nel.org>
CC:     "kishon@...com" <kishon@...com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: RE: [RFC PATCH v2 1/2] dt-bindings: phy: Document cadence Sierra PHY
 bindings

On 25 September 2018 22:02, Rob Herring wrote:
> On Thu, Sep 06, 2018 at 03:42:29PM +0100, Alan Douglas wrote:
> > Add DT binding documentation for Sierra PHY.  The PHY supports
> > a number of different protocols, including PCIe and USB.
> >
> > The PHY lanes may be configured as single or multi-lane links.
> > Each link is treated as a separate subnode.  For example, if
> > there are 4 lanes in total the first 2 may be configured as
> > a multi-lane PCIe link while the other two are single lane
> > USB links, and in this case there would be 3 subnodes.
> >
> > There are two resets for the PHY block, and additional resets,
> > one for each lane.  For multi-lane links, only the reset for
> > the master lane is required, the resets on other lanes have no
> > effect.
> >
> > Signed-off-by: Alan Douglas <adouglas@...ence.com>
> > ---
> >  .../devicetree/bindings/phy/cdns-sierra-phy.txt    | 65 ++++++++++++++++++++++
> >  1 file changed, 65 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/phy/cdns-sierra-phy.txt
> >
> > diff --git a/Documentation/devicetree/bindings/phy/cdns-sierra-phy.txt b/Documentation/devicetree/bindings/phy/cdns-sierra-
> phy.txt
> > new file mode 100644
> > index 0000000..94a8a7f
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/phy/cdns-sierra-phy.txt
> > @@ -0,0 +1,65 @@
> > +Cadence Sierra PHY
> > +-----------------------
> > +
> > +Required properties:
> > +- compatible:	cdns,sierra-phy-t0
> > +- clocks:	Must contain an entry in clock-names.
> > +		See ../clocks/clock-bindings.txt for details.
> > +- clock-names:	Must be "phy_clk"
> > +- resets:	Must contain an entry for each in reset-names.
> > +		See ../reset/reset.txt for details.
> > +- reset-names:	Must include "sierra_reset" and "sierra_apb" and one for each
> > +		sub-node.
> > +		"sierra_reset" must control the reset line to the PHY.
> > +		"sierra_apb" must control the reset line to the APB PHY
> > +		interface.
> > +		Resets for each subnode must control the master lane for the
> > +		subnode lane group.
> 
> What are the names?
> 
I'll update this to use the full name of the subnode, e.g. for subnodes:
  pcie0_phy0: pcie-phy@0
  pcie0_phy1: pcie-phy@2
then the reset names would be: "pcie-phy@0" and "pcie-phy@2"

> > +- reg:		register range for the PHY.
> > +- reg-names:	Must be "reg".
> 
> Kind of pointless with only 1.
> 
I will remove reg-names.

> > +- #address-cells: Should be 1
> > +- #size-cells:	Should be 0
> > +
> > +Optional properties:
> > +- cdns,autoconf:	If present, indicates that the PHY registers will
> > +			be configured by hardware.  If not present, all
> > +			sub-node optional properties must be provided.
> 
> boolean?
Yes, will update the description

> 
> > +
> > +Sub-nodes:
> > +  Each group of PHY lanes with a single master lane should be represented as
> > +  a sub-node. Note that the actual configuration of each lane is determined by
> > +  hardware strapping, and must match the configuration specified here.
> > +
> > +Sub-node required properties:
> > +- #phy-cells:	Generic PHY binding; must be 0.
> > +
> > +Sub-node optional properties:
> > +- reg:			The master lane number.
> > +- cdns,num-lanes:	Number of lanes in this group.  From 1 to 4.
> > +- cdns,phy-type:	Can be PHY_TYPE_PCIE or PHY_TYPE_USB3, depending on
> > +			configuration of lanes.
> > +
> > +Example:
> > +	pcie_phy4: pcie-phy4@...40000 {
> 
> pcie-phy@...40000
> 
I'll change as suggested.

> > +		compatible = "cdns,sierra-phy-t0";
> > +		reg = <0x0 0xfd240000 0x0 0x40000>;
> > +		reg-names = "reg";
> > +		resets = <&phyrst 0>, <&phyrst 1>,<&phyrst 2>,<&phyrst 4>;
> > +		reset-names = "sierra_reset","sierra_apb","pcie_phy0",pcie_phy1;
> 
> spaces and quotes missing.
> 
I'll reformat.

> > +		clocks = <&phyclock>;
> > +		clock-names = "phy_clk";
> > +		#address-cells = <1>;
> > +		#size-cells = <0>;
> > +		pcie0_phy0: pcie-phy0@0 {
> 
> pcie-phy@0
> 
I'll change as suggested.

> > +				reg = <0>;
> > +				cdns,num-lanes = <2>;
> > +				#phy-cells = <0>;
> > +				cdns,phy-type = <PHY_TYPE_PCIE>;
> > +		};
> > +		pcie0_phy1: pcie-phy1@0 {
> 
> pcie-phy@2
> 
> Or reg should be 1?
> 
reg is the master lane number, and in this case must be 2 or higher,
since the subnode with master lane number 0 has 2 lanes.
I'll change to pcie-phy@2, and add an explanation.

Thanks for your comments

> > +				reg = <2>;
> > +				cdns,num-lanes = <1>;
> > +				#phy-cells = <0>;
> > +				cdns,phy-type = <PHY_TYPE_PCIE>;
> > +		};
> > +
> > --
> > 1.9.0
> >