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From: Sai Krishna Gajula <saikrishnag@marvell.com>
To: Vinicius Costa Gomes <vinicius.gomes@intel.com>,
        "richardcochran@gmail.com" <richardcochran@gmail.com>,
        "davem@davemloft.net"
	<davem@davemloft.net>,
        "kuba@kernel.org" <kuba@kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Sunil Kovvuri
 Goutham <sgoutham@marvell.com>,
        Geethasowjanya Akula <gakula@marvell.com>,
        Linu Cherian <lcherian@marvell.com>,
        Hariprasad Kelam <hkelam@marvell.com>,
        Subbaraya Sundeep Bhatta <sbhatta@marvell.com>
CC: Naveen Mamindlapalli <naveenm@marvell.com>
Subject: Re: [net-next PATCH] octeontx2: Add PTP clock driver for Octeon PTM
 clock.
Thread-Topic: [net-next PATCH] octeontx2: Add PTP clock driver for Octeon PTM
 clock.
Thread-Index: AQHaUsULWkwLO8I3d0esTIbEpcakBg==
Date: Mon, 29 Jan 2024 15:08:42 +0000
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> -----Original Message-----
> From: Vinicius Costa Gomes <vinicius.gomes@intel.com>
> Sent: Friday, January 26, 2024 5:41 AM
> To: Sai Krishna Gajula <saikrishnag@marvell.com>;
> richardcochran@gmail.com; davem@davemloft.net; kuba@kernel.org;
> netdev@vger.kernel.org; linux-kernel@vger.kernel.org; Sunil Kovvuri
> Goutham <sgoutham@marvell.com>; Geethasowjanya Akula
> <gakula@marvell.com>; Linu Cherian <lcherian@marvell.com>; Hariprasad
> Kelam <hkelam@marvell.com>; Subbaraya Sundeep Bhatta
> <sbhatta@marvell.com>
> Cc: Sai Krishna Gajula <saikrishnag@marvell.com>; Naveen Mamindlapalli
> <naveenm@marvell.com>
> Subject: Re: [net-next PATCH] octeontx2: Add PTP clock driver for
> Octeon PTM clock.
>=20
> Sai Krishna <saikrishnag@marvell.com> writes:
>=20
> > The PCIe PTM(Precision time measurement) protocol provides precise
> > coordination of events across multiple components like PCIe host
> > clock, PCIe EP PHC local clocks of PCIe devices. This patch adds
> > support for ptp clock based PTM clock. We can use this PTP device to
> > sync the PTM time with CLOCK_REALTIME or other PTP PHC devices using
> > phc2sys.
> >
> > Signed-off-by: Sai Krishna <saikrishnag@marvell.com>
> > Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
> > Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
> > ---
>=20
> I can see that the same device id (PCI_DEVID_OCTEONTX2_PTP) is used by a
> ethernet driver.
>=20
> That brings me a question: why expose a different PTP chardev? In other
> words, why can't you just implement .getcrosststamp() for that ethernet
> device?

This driver runs on endpoint device and not on the host. getcrosststamp() n=
eeds ART time, frequency details in case of x86 host system. Our use case i=
s to sync the host's PTP/PTM time to the endpoint device via PTM interface.

>=20
>=20
> Cheers,
> --
> Vinicius