linux-kernel - Re: PPS functionality for Intel Timed I/O

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Message-ID: <8ca736c3-7da9-2599-7e55-15e2fc9fedc2@enneenne.com>
Date:   Fri, 6 Oct 2023 08:23:09 +0200
From:   Rodolfo Giometti <giometti@...eenne.com>
To:     "N, Pandith" <pandith.n@...el.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Sangannavar, Mallikarjunappa" 
        <mallikarjunappa.sangannavar@...el.com>,
        "D, Lakshmi Sowjanya" <lakshmi.sowjanya.d@...el.com>,
        "T R, Thejesh Reddy" <thejesh.reddy.t.r@...el.com>,
        "Hall, Christopher S" <christopher.s.hall@...el.com>,
        "Gross, Mark" <mark.gross@...el.com>,
        "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>
Subject: Re: PPS functionality for Intel Timed I/O

On 06/10/23 07:31, N, Pandith wrote:
> Hi,

Hello.

>> -----Original Message-----
>> From: Rodolfo Giometti <giometti@...eenne.com>
>> Sent: Wednesday, February 15, 2023 1:16 PM
>> To: N, Pandith <pandith.n@...el.com>
>> Cc: linux-kernel@...r.kernel.org; Sangannavar, Mallikarjunappa
>> <mallikarjunappa.sangannavar@...el.com>; D, Lakshmi Sowjanya
>> <lakshmi.sowjanya.d@...el.com>; T R, Thejesh Reddy
>> <thejesh.reddy.t.r@...el.com>; Hall, Christopher S
>> <christopher.s.hall@...el.com>; Gross, Mark <mark.gross@...el.com>
>> Subject: Re: PPS functionality for Intel Timed I/O
>>
>> On 15/02/23 08:09, N, Pandith wrote:
>>> Hi Rodolfo,
>>
>> Hello.
>>
>>>> -----Original Message-----
>>>> From: Rodolfo Giometti <giometti@...eenne.com>
>>>> Sent: Monday, February 6, 2023 4:17 PM
>>>> To: N, Pandith <pandith.n@...el.com>
>>>> Cc: linux-kernel@...r.kernel.org; Sangannavar, Mallikarjunappa
>>>> <mallikarjunappa.sangannavar@...el.com>; D, Lakshmi Sowjanya
>>>> <lakshmi.sowjanya.d@...el.com>; T R, Thejesh Reddy
>>>> <thejesh.reddy.t.r@...el.com>; Hall, Christopher S
>>>> <christopher.s.hall@...el.com>
>>>> Subject: Re: PPS functionality for Intel Timed I/O
>>
>> [snip]
>>
>>>> Mmm... I'm not sure this is correct since PPS generators should
>>>> generate their pulses according to system clock and not according to
>>>> their internal clocks even if they are synced with the system clock.
>>>>
>>> Timed I/O and system time are both driven by the *same* hardware clock.
>>> Timed I/O is a high precision device (nanoseconds), able to output pulses.
>>> The driver gets the system time and schedules output at target_time in
>>> the future.
>>
>> OK, in this case it would be OK. Please put an appropriate note within the
>> generator's code and a detailed one within Documentation/driver-api/pps.rst.
>>
>> Regarding Documentation/driver-api/pps.rst let me suggest you to prose a
>> separate patch to rewrite the Generators section in such a way you easily can add
>> your solution at the end. A possible example is attached but feel free to rewrite it
>> according to your needs.
>>
> Ok, we are updating documentation as you have suggested as a separate patch.
> Can we use your "Signed-off-by" tag for attached patch.

If you just followed my suggestion then it's OK for me.

> We are adding Intel timed I/O documentation as a separate patch.

OK.

Ciao,

Rodolfo Giometti

-- 
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