From:   <Tharunkumar.Pasumarthi@microchip.com>
To:     <gregkh@linuxfoundation.org>
CC:     <Kumaravel.Thiagarajan@microchip.com>, <arnd@arndb.de>,
        <linux-kernel@vger.kernel.org>, <linux-gpio@vger.kernel.org>,
        <UNGLinuxDriver@microchip.com>, <lkp@intel.com>
Subject: RE: [PATCH v3 char-misc-next] misc: microchip: pci1xxxx: Add
 OTP/EEPROM driver for the pci1xxxx switch
Thread-Topic: [PATCH v3 char-misc-next] misc: microchip: pci1xxxx: Add
 OTP/EEPROM driver for the pci1xxxx switch
Thread-Index: AQHZKXdRTqU9jy+mxk+hberHdhxKbq6nKH0AgBqbxPCAAAdBgIAAekcA
Date:   Mon, 6 Feb 2023 17:03:57 +0000
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References: <20230116192908.2980862-1-kumaravel.thiagarajan@microchip.com>
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> From: Greg KH <gregkh@linuxfoundation.org>
> Sent: Monday, February 6, 2023 3:12 PM
> To: Tharunkumar Pasumarthi - I67821
> <Tharunkumar.Pasumarthi@microchip.com>
> > > > +     delay =3D msecs_to_jiffies(OTP_RW_TIMEOUT_MILLISECONDS);
> > > > +     j0 =3D jiffies;
> > > > +     j1 =3D j0 + delay;
> > >
> > > Are you sure this math works out?  Please use the jiffies math
> > > functions instead so you can handle wrapping properly.
> >
> > You suggest using any existing APIs to add jiffies to handle wrapping?
> > I am not able to find any such API. Can you please point out API name.
>=20
> I have no context here for what you are doing with the math in jiffies, b=
ut
> that is usually a very odd thing.  If you use the normal timer functions,=
 you
> will not have to worry about the wrapping as it is handled for you, right=
?

Hi Greg,
Our objective with that part of code is to wait for OTP_STATUS_BUSY_BIT=20
to be cleared in the hardware, but make sure that we wait for a maximum=20
of OTP_RW_TIMEOUT_MILLISECONDS ms in the driver and not beyond that.=20
This logic is not possible with normal timer functions. Timer wrapping logi=
c is=20
handled by time_before API internally. So, there does not seem to be issue =
with
existing code.=20

Thanks,
Tharun Kumar P