From: Vladimir Oltean <olteanv@gmail.com>
To: Richard Cochran <richardcochran@gmail.com>
Cc: Hubert Feurstein <h.feurstein@gmail.com>,
netdev <netdev@vger.kernel.org>,
lkml <linux-kernel@vger.kernel.org>, Andrew Lunn <andrew@lunn.ch>,
Vivien Didelot <vivien.didelot@gmail.com>,
Florian Fainelli <f.fainelli@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Subject: Re: [PATCH 4/4] net: dsa: mv88e6xxx: add PTP support for MV88E6250 family
Date: Tue, 30 Jul 2019 23:46:51 +0300 [thread overview]
Message-ID: <CA+h21hqWO=qT6EuQOVgX=J1=m60AWT6EGvQgfzGS=BNNq1cyTg@mail.gmail.com> (raw)
In-Reply-To: <20190730171246.GB1251@localhost>
Hi Hubert, Richard,
On Tue, 30 Jul 2019 at 19:44, Richard Cochran <richardcochran@gmail.com> wrote:
>
> On Tue, Jul 30, 2019 at 12:04:29PM +0200, Hubert Feurstein wrote:
> > diff --git a/drivers/net/dsa/mv88e6xxx/ptp.c b/drivers/net/dsa/mv88e6xxx/ptp.c
> > index 768d256f7c9f..51cdf4712517 100644
> > --- a/drivers/net/dsa/mv88e6xxx/ptp.c
> > +++ b/drivers/net/dsa/mv88e6xxx/ptp.c
> > @@ -15,11 +15,38 @@
> > #include "hwtstamp.h"
> > #include "ptp.h"
> >
> > -/* Raw timestamps are in units of 8-ns clock periods. */
> > -#define CC_SHIFT 28
> > -#define CC_MULT (8 << CC_SHIFT)
> > -#define CC_MULT_NUM (1 << 9)
> > -#define CC_MULT_DEM 15625ULL
> > +/* The adjfine API clamps ppb between [-32,768,000, 32,768,000], and
>
> That is not true.
>
I was referring to this:
https://github.com/richardcochran/linuxptp/blob/master/phc.c#L38
/*
* On 32 bit platforms, the PHC driver's maximum adjustment (type
* 'int' in units of ppb) can overflow the timex.freq field (type
* 'long'). So in this case we clamp the maximum to the largest
* possible adjustment that fits into a 32 bit long.
*/
#define BITS_PER_LONG (sizeof(long)*8)
#define MAX_PPB_32 32767999 /* 2^31 - 1 / 65.536 */
Technically it is not "not true".
[snip]
On Tue, 30 Jul 2019 at 21:09, Richard Cochran <richardcochran@gmail.com> wrote:
>
> On Tue, Jul 30, 2019 at 06:20:00PM +0200, Hubert Feurstein wrote:
> > > Please don't re-write this logic. It is written like that for a reason.
> > I used the sja1105_ptp.c as a reference. So it is also wrong there.
>
> I'll let that driver's author worry about that.
>
> Thanks,
> Richard
>
And what is the reason for the neg_adj thing? Can you give an example
of when does the "normal way" of doing signed arithmetics not work?
Thanks,
-Vladimir
next prev parent reply other threads:[~2019-07-30 20:47 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-30 10:04 [PATCH 0/4] net: dsa: mv88e6xxx: add support for MV88E6220 Hubert Feurstein
2019-07-30 10:04 ` [PATCH 1/4] " Hubert Feurstein
2019-07-30 13:36 ` Andrew Lunn
2019-07-30 13:49 ` Andrew Lunn
2019-07-30 14:00 ` Hubert Feurstein
2019-07-30 10:04 ` [PATCH 2/4] dt-bindings: net: dsa: marvell: add 6220 model to the 6250 family Hubert Feurstein
2019-07-30 13:37 ` Andrew Lunn
2019-07-30 10:04 ` [PATCH 3/4] net: dsa: mv88e6xxx: setup message port is not supported in " Hubert Feurstein
2019-07-30 13:40 ` Andrew Lunn
2019-07-30 10:04 ` [PATCH 4/4] net: dsa: mv88e6xxx: add PTP support for MV88E6250 family Hubert Feurstein
2019-07-30 13:58 ` Andrew Lunn
2019-07-30 16:00 ` Richard Cochran
2019-07-30 16:20 ` Hubert Feurstein
2019-07-30 17:12 ` Richard Cochran
2019-07-30 20:46 ` Vladimir Oltean [this message]
2019-07-31 4:30 ` Richard Cochran
2019-07-30 14:03 ` [PATCH 0/4] net: dsa: mv88e6xxx: add support for MV88E6220 Andrew Lunn
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