RE: [EXT] Re: [PATCH v2 1/3] dt-bindings: usb: cdns-imx8qm: add imx8qm cdns3 glue bindings

[Frank Li <frank.li@nxp.com>]

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Sent: Friday, March 17, 2023 4:09 AM
> To: Frank Li <frank.li@nxp.com>; shawnguo@kernel.org
> Cc: devicetree@vger.kernel.org; festevam@gmail.com; imx@lists.linux.dev;
> kernel@pengutronix.de; krzysztof.kozlowski+dt@linaro.org; linux-arm-
> kernel@lists.infradead.org; dl-linux-imx <linux-imx@nxp.com>; linux-
> kernel@vger.kernel.org; robh+dt@kernel.org; s.hauer@pengutronix.de
> Subject: [EXT] Re: [PATCH v2 1/3] dt-bindings: usb: cdns-imx8qm: add
> imx8qm cdns3 glue bindings
> 
> Caution: EXT Email
> 
> On 16/03/2023 22:27, Frank Li wrote:
> > NXP imx8qm integrates 1 cdns3 IP. This is glue layer device bindings.
> >
> 
> Subject: drop second/last, redundant "bindings". The "dt-bindings"
> prefix is already stating that these are bindings.
> 
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> >  .../bindings/usb/fsl,imx8qm-cdns3.yaml        | 122 ++++++++++++++++++
> >  1 file changed, 122 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/usb/fsl,imx8qm-
> cdns3.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/usb/fsl,imx8qm-
> cdns3.yaml b/Documentation/devicetree/bindings/usb/fsl,imx8qm-
> cdns3.yaml
> > new file mode 100644
> > index 000000000000..fc24df1e4483
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/usb/fsl,imx8qm-cdns3.yaml
> > @@ -0,0 +1,122 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +# Copyright (c) 2020 NXP
> > +%YAML 1.2
> > +---
> > +$id:
> https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevice
> tree.org%2Fschemas%2Fusb%2Ffsl%2Cimx8qm-
> cdns3.yaml%23&data=05%7C01%7CFrank.Li%40nxp.com%7Cac9af3d617dc4cf
> 14baf08db26c74b07%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6
> 38146409617970248%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMD
> AiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C
> &sdata=EczZhjyMUGnnp7ZGfSvTj4lmOUuGlOtWYIsxxXIlNXw%3D&reserved
> =0
> > +$schema:
> https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevice
> tree.org%2Fmeta-
> schemas%2Fcore.yaml%23&data=05%7C01%7CFrank.Li%40nxp.com%7Cac9a
> f3d617dc4cf14baf08db26c74b07%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C
> 0%7C0%7C638146409617970248%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiM
> C4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000
> %7C%7C%7C&sdata=uTNYuDm%2ByhZ56oQET2pX8sHpEqVvsUYtmOBCPXEK
> v40%3D&reserved=0
> > +
> > +title: NXP iMX8QM Soc USB Controller
> > +
> > +maintainers:
> > +  - Frank Li <Frank.Li@nxp.com>
> > +
> > +properties:
> > +  compatible:
> > +    const: fsl,imx8qm-usb3
> > +
> > +  reg:
> > +    items:
> > +      - description: Address and length of the register set for iMX USB3
> Platform Control
> 
> Drop "Address and length of the"... or actually just maxItems: 1,
> because the description is a bit obvious.
> 
> > +
> > +  "#address-cells":
> > +    enum: [ 1, 2 ]
> > +
> > +  "#size-cells":
> > +    enum: [ 1, 2 ]
> > +
> > +  ranges: true
> > +
> > +  clocks:
> > +    description:
> > +      A list of phandle and clock-specifier pairs for the clocks
> > +      listed in clock-names.
> 
> Drop description.
> 
> > +    items:
> > +      - description: Standby clock. Used during ultra low power states.
> > +      - description: USB bus clock for usb3 controller.
> > +      - description: AXI clock for AXI interface.
> > +      - description: ipg clock for register access.
> > +      - description: Core clock for usb3 controller.
> > +
> > +  clock-names:
> > +    items:
> > +      - const: usb3_lpm_clk
> > +      - const: usb3_bus_clk
> > +      - const: usb3_aclk
> > +      - const: usb3_ipg_clk
> > +      - const: usb3_core_pclk
> > +
> > +  assigned-clocks:
> > +    items:
> > +      - description: Phandle and clock specifier of IMX_SC_PM_CLK_PER.
> > +      - description: Phandle and clock specifoer of IMX_SC_PM_CLK_MISC.
> > +      - description: Phandle and clock specifoer of
> IMX_SC_PM_CLK_MST_BUS.
> > +
> > +  assigned-clock-rates:
> > +    items:
> > +      - description: Must be 125 Mhz.
> > +      - description: Must be 12 Mhz.
> > +      - description: Must be 250 Mhz.
> 
> I would argue that both properties above are not needed. If your
> hardware requires fixed frequencies, clock provider can fix them, can't it?

Clock provider don't know fixed value and turn on only used by client. 

> 
> > +
> > +  power-domains:
> > +    maxItems: 1
> > +
> > +# Required child node:
> > +
> > +patternProperties:
> > +  "^usb@[0-9a-f]+$":
> > +    $ref: cdns,usb3.yaml#
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - "#address-cells"
> > +  - "#size-cells"
> > +  - ranges
> > +  - clocks
> > +  - clock-names
> > +  - power-domains
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/clock/imx8-lpcg.h>
> > +    #include <dt-bindings/firmware/imx/rsrc.h>
> > +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> > +
> > +    usbotg3: usb@5b110000 {
> 
> Drop label, unused
> 
> > +      compatible = "fsl,imx8qm-usb3";
> > +      ranges;
> > +      reg = <0x5b110000 0x10000>;
> 
> reg is second property
> 
> > +      clocks = <&usb3_lpcg IMX_LPCG_CLK_1>,
> > +               <&usb3_lpcg IMX_LPCG_CLK_0>,
> > +               <&usb3_lpcg IMX_LPCG_CLK_7>,
> > +               <&usb3_lpcg IMX_LPCG_CLK_4>,
> > +               <&usb3_lpcg IMX_LPCG_CLK_5>;
> > +      clock-names = "usb3_lpm_clk", "usb3_bus_clk", "usb3_aclk",
> > +                    "usb3_ipg_clk", "usb3_core_pclk";
> > +      assigned-clocks = <&clk IMX_SC_R_USB_2 IMX_SC_PM_CLK_PER>,
> > +                        <&clk IMX_SC_R_USB_2 IMX_SC_PM_CLK_MISC>,
> > +                        <&clk IMX_SC_R_USB_2 IMX_SC_PM_CLK_MST_BUS>;
> > +      assigned-clock-rates = <125000000>, <12000000>, <250000000>;
> > +      power-domains = <&pd IMX_SC_R_USB_2>;
> > +      #address-cells = <1>;
> > +      #size-cells = <1>;
> > +      status = "disabled";
> 
> Drop status
> 
> > +
> > +      usbotg3_cdns3: usb@5b120000 {
> 
> Drop label
> 
> > +          compatible = "cdns,usb3";
> > +          interrupt-parent = <&gic>;
> > +          interrupts = <GIC_SPI 271 IRQ_TYPE_LEVEL_HIGH>,
> > +                       <GIC_SPI 271 IRQ_TYPE_LEVEL_HIGH>,
> > +                       <GIC_SPI 271 IRQ_TYPE_LEVEL_HIGH>,
> > +                       <GIC_SPI 271 IRQ_TYPE_LEVEL_HIGH>;
> > +          interrupt-names = "host", "peripheral", "otg", "wakeup";
> > +          reg = <0x5b120000 0x10000>,   /* memory area for OTG/DRD
> registers */
> > +                <0x5b130000 0x10000>,   /* memory area for HOST registers */
> > +                <0x5b140000 0x10000>;   /* memory area for DEVICE registers */
> > +          reg-names = "otg", "xhci", "dev";
> 
> reg is second property, reg-names third.
> 
> > +          phys = <&usb3_phy>;
> > +          phy-names = "cdns3,usb3-phy";
> > +      };
> > +    };
> 
> Best regards,
> Krzysztof