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From:   "N, Pandith" <pandith.n@intel.com>
To:     Dipen Patel <dipenp@nvidia.com>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Hall, Christopher S" <christopher.s.hall@intel.com>,
        "Gross, Mark" <mark.gross@intel.com>,
        "Sangannavar, Mallikarjunappa" 
        <mallikarjunappa.sangannavar@intel.com>,
        "D, Lakshmi Sowjanya" <lakshmi.sowjanya.d@intel.com>,
        "T R, Thejesh Reddy" <thejesh.reddy.t.r@intel.com>,
        "andriy.shevchenko@linux.intel.com" 
        <andriy.shevchenko@linux.intel.com>
Subject: Intel timed i/o driver in HTE
Thread-Topic: Intel timed i/o driver in HTE
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Date:   Thu, 17 Nov 2022 18:47:39 +0000
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Hi Dipen,

To support Intel timed i/o driver, it was suggested by Linux community to e=
nhance hte framework.
However, we see some limitations to support complete Intel timed i/o device=
.

1. The current framework supports Nvidia IP, which has two IP blocks (hw ti=
mestamping engine interfaced with GPIO)
Intel timed i/o is a single IP block handling multiple functionalities like=
:

	a. Input timestamping with event counter.
	b. Timed output  - single shot or periodic pulse train.
	Uses TSC(Timestamp counter) for timestamp or generate events, which could =
be translated to system time.
	c. Implement PPS functionality to export time.

This requires new functionality(interface) to be developed in hte framework=
 specific to timed-io device.

2. The current hte framework has a provider and consumer concept.
Consumer is responsible for user space interaction.
Currently Nvidia is using GPIO for input timestamping  (by adding hw timest=
amps in gpiolib-cdev.c)

For Intel timed i/o functionalities, current gpio user interfaces cannot su=
pport event counter
or output modes.
Rather than jigging hte consumer into other subsystems to support timed i/o=
 device.=20
Any possibility of developing a native consumer in hte subsystem, which cou=
ld handle user space interactions for timestamping engines.

I cannot think of an existing subsystem that handles Intel timed i/o functi=
onalities 1a, 1b and 1c (mentioned above).

Regards,
Pandith