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Date: Wed, 3 Jan 2024 14:13:12 -0800
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Subject: Re: [RFC PATCH v3 10/11] Documentation: driver-api: pps: Add Intel
 Timed I/O PPS generator
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To: lakshmi.sowjanya.d@intel.com, tglx@linutronix.de, jstultz@google.com,
 giometti@enneenne.com, corbet@lwn.net, linux-kernel@vger.kernel.org
Cc: x86@kernel.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org,
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 anthony.l.nguyen@intel.com, pandith.n@intel.com,
 mallikarjunappa.sangannavar@intel.com, thejesh.reddy.t.r@intel.com
References: <20240103115602.19044-1-lakshmi.sowjanya.d@intel.com>
 <20240103115602.19044-11-lakshmi.sowjanya.d@intel.com>
From: Randy Dunlap <rdunlap@infradead.org>
In-Reply-To: <20240103115602.19044-11-lakshmi.sowjanya.d@intel.com>
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On 1/3/24 03:56, lakshmi.sowjanya.d@intel.com wrote:
> From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
> 
> Add Intel Timed I/O PPS usage instructions.
> 
> Co-developed-by: Pandith N <pandith.n@intel.com>
> Signed-off-by: Pandith N <pandith.n@intel.com>
> Signed-off-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  Documentation/driver-api/pps.rst | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/Documentation/driver-api/pps.rst b/Documentation/driver-api/pps.rst
> index 78dded03e5d8..cb1e4d814d37 100644
> --- a/Documentation/driver-api/pps.rst
> +++ b/Documentation/driver-api/pps.rst
> @@ -246,3 +246,25 @@ delay between assert and clear edge as small as possible to reduce system
>  latencies. But if it is too small slave won't be able to capture clear edge
>  transition. The default of 30us should be good enough in most situations.
>  The delay can be selected using 'delay' pps_gen_parport module parameter.
> +
> +
> +Intel Timed I/O PPS signal generator
> +------------------------------------
> +
> +Intel Timed I/O is a high precision device, present on 2019 and newer Intel
> +CPUs, that can generate PPS signal.

              can generate a PPS signal.
or
              can generate PPS signals.

> +
> +Timed I/O and system time are both driven by same hardware clock, The signal

                                                              clock. The signal is

> +generated with a precision of ~20 nanoseconds. The generated PPS signal
> +is used to synchronize an external device with system clock. For example,
> +Share your clock with a device that receives PPS signal, generated by

   share

> +Timed I/O device. There are dedicated Timed I/O pins to deliver PPS signal

maybe:                                                  to deliver the PPS signal

> +to an external device.
> +
> +Usage of Intel Timed I/O as PPS generator:
> +
> +Start generating PPS signal::
> +        $echo 1 > /sys/devices/platform/INTCxxxx\:00/enable
> +
> +Stop generating PPS signal::
> +        $echo 0 > /sys/devices/platform/INTCxxxx\:00/enable

-- 
#Randy