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From: Richard Cochran <richardcochran@gmail.com>
To: "Mintz, Yuval" <Yuval.Mintz@cavium.com>
Cc: "davem@davemloft.net" <davem@davemloft.net>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"Kalluru, Sudarsana" <Sudarsana.Kalluru@cavium.com>
Subject: Re: [PATCH net-next v4 1/2] qed: Add infrastructure for PTP support.
Date: Sun, 12 Feb 2017 19:47:58 +0100	[thread overview]
Message-ID: <20170212184758.GA1703@localhost.localdomain> (raw)
In-Reply-To: <BL2PR07MB230689D83356C4577C8AB1E58D460@BL2PR07MB2306.namprd07.prod.outlook.com>

On Sun, Feb 12, 2017 at 11:52:23AM +0000, Mintz, Yuval wrote:
> Just to clarify [since it's bit a meaningless otherwise] -
> this +8 is a HW-bug workaround.

Can you please explain exactly what the problem is?

Your code does

		period1 = div_s64(val * 1000000000, ppb);
		period1 -= 8;
		period1 >>= 4;

But correct rounding would be

		period1 = div_s64(val * 1000000000, ppb);
		period1 += 8;
		period1 >>= 4;

Thanks,
Richard

  reply	other threads:[~2017-02-12 18:48 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-08  6:43 [PATCH net-next v4 0/2] qed*: Add support for PTP Sudarsana Kalluru
2017-02-08  6:43 ` [PATCH net-next v4 1/2] qed: Add infrastructure for PTP support Sudarsana Kalluru
2017-02-11  8:58   ` Richard Cochran
2017-02-11 11:16     ` Richard Cochran
2017-02-12 11:27       ` Mintz, Yuval
2017-02-12 11:52         ` Mintz, Yuval
2017-02-12 18:47           ` Richard Cochran [this message]
2017-02-12 14:02         ` Richard Cochran
2017-02-12 15:07           ` Mintz, Yuval
2017-02-12 15:53             ` Mintz, Yuval
2017-02-12 19:50             ` Richard Cochran
2017-02-13  9:48               ` FW: " Mintz, Yuval
2017-02-08  6:43 ` [PATCH net-next v4 2/2] qede: Add driver support for PTP Sudarsana Kalluru

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