linux-kernel - Re: [PATCH v3 net-next 01/15] dt-bindings: ptp: add NETC Timer PTP clock

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Message-ID: <cf531bbd-dc07-4c13-9dbb-774c8dfca70c@kernel.org>
Date: Fri, 15 Aug 2025 08:05:12 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Frank Li <Frank.li@....com>
Cc: Wei Fang <wei.fang@....com>, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.org, richardcochran@...il.com, claudiu.manoil@....com,
 vladimir.oltean@....com, xiaoning.wang@....com, andrew+netdev@...n.ch,
 davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, vadim.fedorenko@...ux.dev, shawnguo@...nel.org,
 s.hauer@...gutronix.de, festevam@...il.com, fushi.peng@....com,
 devicetree@...r.kernel.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, imx@...ts.linux.dev, kernel@...gutronix.de
Subject: Re: [PATCH v3 net-next 01/15] dt-bindings: ptp: add NETC Timer PTP
 clock

On 14/08/2025 20:50, Frank Li wrote:
> On Thu, Aug 14, 2025 at 10:25:14AM +0200, Krzysztof Kozlowski wrote:
>> On Tue, Aug 12, 2025 at 05:46:20PM +0800, Wei Fang wrote:
>>> NXP NETC (Ethernet Controller) is a multi-function PCIe Root Complex
>>> Integrated Endpoint (RCiEP), the Timer is one of its functions which
>>> provides current time with nanosecond resolution, precise periodic
>>> pulse, pulse on timeout (alarm), and time capture on external pulse
>>> support. And also supports time synchronization as required for IEEE
>>> 1588 and IEEE 802.1AS-2020. So add device tree binding doc for the
>>> PTP clock based on NETC Timer.
>>>
>>> Signed-off-by: Wei Fang <wei.fang@....com>
>>>
>>> ---
>>> v2 changes:
>>> 1. Refine the subject and the commit message
>>> 2. Remove "nxp,pps-channel"
>>> 3. Add description to "clocks" and "clock-names"
>>> v3 changes:
>>> 1. Remove the "system" clock from clock-names
>>> ---
>>>  .../devicetree/bindings/ptp/nxp,ptp-netc.yaml | 63 +++++++++++++++++++
>>>  1 file changed, 63 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/ptp/nxp,ptp-netc.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/ptp/nxp,ptp-netc.yaml b/Documentation/devicetree/bindings/ptp/nxp,ptp-netc.yaml
>>> new file mode 100644
>>> index 000000000000..60fb2513fd76
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/ptp/nxp,ptp-netc.yaml
>>> @@ -0,0 +1,63 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/ptp/nxp,ptp-netc.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: NXP NETC V4 Timer PTP clock
>>> +
>>> +description:
>>> +  NETC V4 Timer provides current time with nanosecond resolution, precise
>>> +  periodic pulse, pulse on timeout (alarm), and time capture on external
>>> +  pulse support. And it supports time synchronization as required for
>>> +  IEEE 1588 and IEEE 802.1AS-2020.
>>> +
>>> +maintainers:
>>> +  - Wei Fang <wei.fang@....com>
>>> +  - Clark Wang <xiaoning.wang@....com>
>>> +
>>> +properties:
>>> +  compatible:
>>> +    enum:
>>> +      - pci1131,ee02
>>> +
>>> +  reg:
>>> +    maxItems: 1
>>> +
>>> +  clocks:
>>> +    maxItems: 1
>>> +    description:
>>> +      The reference clock of NETC Timer, if not present, indicates that
>>> +      the system clock of NETC IP is selected as the reference clock.
>>> +
>>> +  clock-names:
>>> +    description:
>>> +      The "ccm_timer" means the reference clock comes from CCM of SoC.
>>> +      The "ext_1588" means the reference clock comes from external IO
>>> +      pins.
>>> +    enum:
>>> +      - ccm_timer
>>
>> You should name here how the input pin is called, not the source. Pin is
>> "ref"?
>>
>>> +      - ext_1588
>>
>> This should be just "ext"? We probably talked about this, but this feels
>> like you describe one input in different ways.
>>
>> You will get the same questions in the future, if commit msg does not
>> reflect previous talks.
>>
>>> +
>>> +required:
>>> +  - compatible
>>> +  - reg
>>> +
>>> +allOf:
>>> +  - $ref: /schemas/pci/pci-device.yaml
>>> +
>>> +unevaluatedProperties: false
>>> +
>>> +examples:
>>> +  - |
>>> +    pcie {
>>> +        #address-cells = <3>;
>>> +        #size-cells = <2>;
>>> +
>>> +        ethernet@18,0 {
>>
>> That's rather timer or ptp-timer or your binding is incorrect. Please
>> describe COMPLETE device in your binding.
> 
> Krzysztof:
> 
> 	I have question about "COMPLETE" here. For some MFD/syscon, I know
> need descript all children nodes to make MFD/syscon complete.
> 
> 	But here it is PCIe device.
> 
> pcie_4ca00000: pcie@...00000 {
> 	compatible = "pci-host-ecam-generic";
> 	...
> 
> 	enetc_port0: ethernet@0,0 {
>         	compatible = "fsl,imx95-enetc", "...";
> 		...
> 
> 	ptp-timer@18,0 {
> 		compatible = "pci1131,ee02";
> 	}
> };
> 
> 	parent "pci-host-ecam-generic" is common pci binding, each children
> is indepentant part.
> 
> 	I am not sure how to decript COMPLETE device for PCI devices.

I don't know what is missing here, but naming it ethernet suggested
there are other functions not being described in the binding.



Best regards,
Krzysztof