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From:   Min Li <min.li.xe@renesas.com>
To:     Greg KH <gregkh@linuxfoundation.org>
CC:     "derek.kiernan@xilinx.com" <derek.kiernan@xilinx.com>,
        "dragan.cvetic@xilinx.com" <dragan.cvetic@xilinx.com>,
        "arnd@arndb.de" <arnd@arndb.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH misc] misc: Add Renesas Synchronization Management Unit
 (SMU) support
Thread-Topic: [PATCH misc] misc: Add Renesas Synchronization Management Unit
 (SMU) support
Thread-Index: AQHXoCrWcPCOZLcVpEOu9zHAf9JJVKujT1SAgAC5dCCAAJ7XAIAAlN8g
Date:   Wed, 15 Sep 2021 14:42:55 +0000
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> > > > +/*
> > > > + * RSMU IOCTL List
> > > > + */
> > > > +#define RSMU_MAGIC '?'
> > >
> > > Where did you get this value from?
> > >
> > > Where did you reserve it?
> >
> > No I didn't reserve it. I checked other code and they all seem to use
> > a random character
>=20
> That's not the best way to do this.
>=20
> Why do you need ioctls at all anyway?  What userspace tools will be
> accessing this driver?  Do you have a link to where they are located at?

Hi Greg

The userspace tool is called PCM4L (PTP Clock Manager for Linux) from Renes=
as

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

But the functions of this misc driver is not ptp related. It is meant for b=
eing called by pcm4l to
support GNSS assisted partial timing support (APTS), which doesn't have abs=
tracted/dedicated
Linux Kernel API's. That is why I went for IOCTL in the first place.

Thanks

Min