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From: Andrew Lunn <andrew@lunn•ch>
To: Piergiorgio Beruto <piergiorgio.beruto@gmail•com>
Cc: Kurt Kanzenbach <kurt@linutronix•de>,
	Jakub Kicinski <kuba@kernel•org>,
	netdev@vger•kernel.org, peppe.cavallaro@st•com,
	Voon Weifeng <weifeng.voon@intel•com>,
	Rayagond Kokatanur <rayagond@vayavyalabs•com>,
	Jose Abreu <Jose.Abreu@synopsys•com>,
	Antonio Borneo <antonio.borneo@st•com>,
	Tan Tee Min <tee.min.tan@intel•com>
Subject: Re: [PATCH net] stmmac: fix potential division by 0
Date: Sat, 10 Dec 2022 11:50:26 +0100	[thread overview]
Message-ID: <Y5RkcmMxK0rmDHtz@lunn.ch> (raw)
In-Reply-To: <Y5GuHEn161H35/xZ@gvm01>

On Thu, Dec 08, 2022 at 10:27:56AM +0100, Piergiorgio Beruto wrote:
> > > 
> > > Here's the Altera manual:
> > > 
> > >  https://www.intel.com/content/www/us/en/docs/programmable/683126/21-2/functional-description-of-the-emac.html
> > > 
> > > Table 183 shows the minimum PTP frequencies and also states "Therefore,
> > > a higher PTP clock frequency gives better system performance.".
> > > 
> > > So, I'd say using a clock of 2.5MHz seems possible, but will result in
> > > suboptimal precision.
> > 
> > Thanks for the info. So i seems like the correct fix is to camp to
> > 0xff, rather than mask with 0xff.

> Andrew, given your comment, do you wish me to re-post the patch with
> this fix? Or wait for more feedback first?

Please post a patch. Often the only way to get feedback is to break systems :-(

In this case, clamping actually seems like it could fix systems, not
break them.

      Andrew

      reply	other threads:[~2022-12-10 10:51 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-01  0:37 [PATCH net] stmmac: fix potential division by 0 Piergiorgio Beruto
2022-12-01  1:39 ` Andrew Lunn
2022-12-01 10:24   ` Piergiorgio Beruto
2022-12-01 14:49     ` Andrew Lunn
2022-12-02  8:26       ` Piergiorgio Beruto
2022-12-07  2:28       ` Jakub Kicinski
2022-12-07 13:48         ` Andrew Lunn
2022-12-07 14:50           ` Kurt Kanzenbach
2022-12-08  0:26             ` Andrew Lunn
2022-12-08  9:27               ` Piergiorgio Beruto
2022-12-10 10:50                 ` Andrew Lunn [this message]

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