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From:   Min Li <min.li.xe@renesas.com>
To:     Greg KH <gregkh@linuxfoundation.org>
CC:     "arnd@arndb.de" <arnd@arndb.de>,
        "derek.kiernan@xilinx.com" <derek.kiernan@xilinx.com>,
        "dragan.cvetic@xilinx.com" <dragan.cvetic@xilinx.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "lee.jones@linaro.or" <lee.jones@linaro.or>
Subject: RE: [PATCH misc v2 2/2] misc: Add Renesas Synchronization Management
 Unit (SMU) support
Thread-Topic: [PATCH misc v2 2/2] misc: Add Renesas Synchronization Management
 Unit (SMU) support
Thread-Index: AQHXqmIqGzfEPA/ASUKU/78egiaTO6umId8AgACkSYA=
Date:   Thu, 16 Sep 2021 15:33:06 +0000
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> -----Original Message-----
> From: Greg KH <gregkh@linuxfoundation.org>
> Sent: September 16, 2021 1:26 AM
> To: Min Li <min.li.xe@renesas.com>
> Cc: arnd@arndb.de; derek.kiernan@xilinx.com; dragan.cvetic@xilinx.com;
> linux-kernel@vger.kernel.org; lee.jones@linaro.or
> Subject: Re: [PATCH misc v2 2/2] misc: Add Renesas Synchronization
> Management Unit (SMU) support
>=20
> On Wed, Sep 15, 2021 at 02:47:09PM -0400, min.li.xe@renesas.com wrote:
> > From: Min Li <min.li.xe@renesas.com>
> >
> > This driver is developed for the IDT ClockMatrix(TM) and 82P33xxx
> > families of timing and synchronization devices.It will be used by
> > Renesas PTP Clock Manager for Linux (pcm4l) software to provide
> > support to GNSS assisted partial timing support (APTS) and other
> networking timing functions.
>=20
> Where is that software?

https://www.renesas.com/us/en/software-tool/ptp-clock-manager-linux

>=20
> Why is this new api not a standard one?
>=20

There is no actual standard for the GNSS assisted partial timing support (A=
PTS)
In terms of Linux kernel API

> What is the standard here?
>=20
> What do other devices do and why is this a new api?
>=20

There is really no standard for APTS and different company has its own hw/s=
w solutions

> > Current version provides kernel API's to support the following
> > functions -set combomode to enable SYNCE clock support -read dpll's
> > state to determine if the dpll is locked to the GNSS channel -read
> > dpll's ffo (fractional frequency offset) in ppqt
>=20
> Why do all of these have to be in the kernel at all?
>=20

Because all these API's need spi/i2c accesses to the RSMU card and spi/i2c =
accesses have been
abstracted to the MFD driver in kernel

> thanks,
>=20
> greg k-h