From: Richard Cochran <richardcochran@gmail•com>
To: Andrew Jackson <ajackson@solarflare•com>
Cc: Ben Hutchings <bhutchings@solarflare•com>,
David Miller <davem@davemloft•net>,
netdev@vger•kernel.org, linux-net-drivers@solarflare•com
Subject: Re: [PATCH net-next 4/7] sfc: Add support for IEEE-1588 PTP
Date: Fri, 20 Jul 2012 08:11:32 +0200 [thread overview]
Message-ID: <20120720061132.GA2330@netboy.at.omicron.at> (raw)
In-Reply-To: <50083059.7070700@solarflare.com>
On Thu, Jul 19, 2012 at 05:05:45PM +0100, Andrew Jackson wrote:
> On 19/07/2012 15:37, Ben Hutchings wrote:
> >On Thu, 2012-07-19 at 16:25 +0200, Richard Cochran wrote:
> >>
> >>I am trying to purge the whole SYS thing (only blackfin is left)
> >>because there is a much better way to go about this, namely
> >>synchronizing the system time to the PHC time via an internal PPS
> >>signal.
> >
> >Andrew, would that work for us?
>
> I don't think so for the reason that Stu has pointed out (failed
> assumption).
>
> The NIC's clock isn't directly accessible by the host from the PCIe
> bus and is "behind" the MC. Even when we process PPS events, we need
> a reliable way of determining the relationship between the two
> clocks (system <> NIC). We're trying to get that as accurately as we
> can but we know that some measurements will be incorrect/out of
> bounds because of loading on the system.
There is a better way to filter out bad measurements than to hard code
some black magic into the driver. Instead, just offer a PPS, and then
we can comfortably (and flexibly) filter using a user space program.
Thanks,
Richard
next prev parent reply other threads:[~2012-07-20 6:11 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-18 18:16 pull request: sfc-next 2012-07-18 Ben Hutchings
2012-07-18 18:19 ` [PATCH net-next 1/7] sfc: Add explicit RX queue flag to channel Ben Hutchings
2012-07-18 18:20 ` [PATCH net-next 2/7] sfc: Add channel specific receive_skb handler and post_remove callback Ben Hutchings
2012-07-18 18:32 ` David Miller
2012-07-18 18:42 ` Ben Hutchings
2012-07-18 18:43 ` David Miller
2012-07-18 18:20 ` [PATCH net-next 3/7] sfc: Allow efx_mcdi_rpc to be called in two parts Ben Hutchings
2012-07-18 18:21 ` [PATCH net-next 4/7] sfc: Add support for IEEE-1588 PTP Ben Hutchings
2012-07-19 14:25 ` Richard Cochran
2012-07-19 14:37 ` Ben Hutchings
2012-07-19 16:05 ` Andrew Jackson
2012-07-20 6:11 ` Richard Cochran [this message]
2012-07-19 15:29 ` Stuart Hodgson
2012-07-19 15:43 ` David Miller
2012-07-19 15:50 ` Ben Hutchings
2012-07-20 7:37 ` Richard Cochran
2012-07-20 6:31 ` Richard Cochran
2012-07-20 9:15 ` Stuart Hodgson
2012-07-20 15:30 ` Richard Cochran
2012-07-30 10:03 ` Stuart Hodgson
2012-07-18 18:21 ` [PATCH net-next 5/7] sfc: Support variable-length response to MCDI GET_BOARD_CFG Ben Hutchings
2012-07-18 18:22 ` [PATCH net-next 6/7] sfc: Expose FPGA bitfile partition through MTD Ben Hutchings
2012-07-18 18:22 ` [PATCH net-next 7/7] sfc: Bump version to 3.2 Ben Hutchings
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