netdev - Re: [RFC 0/3] ptp: Add esterror support

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Message-ID: <9a15379e-9c1e-4778-bda1-38474a8d9317@meta.com>
Date: Thu, 15 Aug 2024 10:29:07 +0000
From: Vadim Fedorenko <vadfed@...a.com>
To: Maciek Machnikowski <maciek@...hnikowski.net>,
        "kuba@...nel.org"
	<kuba@...nel.org>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "richardcochran@...il.com" <richardcochran@...il.com>,
        "jacob.e.keller@...el.com" <jacob.e.keller@...el.com>,
        "darinzon@...zon.com"
	<darinzon@...zon.com>
Subject: Re: [RFC 0/3] ptp: Add esterror support

On 15/08/2024 10:35, Maciek Machnikowski wrote:
> > 
> 
> 
> On 15/08/2024 02:41, Jakub Kicinski wrote:
>> On Tue, 13 Aug 2024 12:55:59 +0000 Maciek Machnikowski wrote:
>>> This patch series implements handling of timex esterror field
>>> by ptp devices.
>>>
>>> Esterror field can be used to return or set the estimated error
>>> of the clock. This is useful for devices containing a hardware
>>> clock that is controlled and synchronized internally (such as
>>> a time card) or when the synchronization is pushed to the embedded
>>> CPU of a DPU.
>>>
>>> Current implementation of ADJ_ESTERROR can enable pushing
>>> current offset of the clock calculated by a userspace app
>>> to the device, which can act upon this information by enabling
>>> or disabling time-related functions when certain boundaries
>>> are not met (eg. packet launchtime)
>>
>> Please do CC people who are working on the VM / PTP / vdso thing,
>> and time people like tglx. And an implementation for a real device
>> would be nice to establish attention.
> 
> Noted - will CC in future releases.
> 
> AWS planned the implementation in ENA driver - will work with David on
> making it part of the patchset once we "upgrade" from an RFC - but
> wanted to discuss the approach first.

I can implement the interface for OCP TimeCard too, I think we have HW
information about it already.