Messages in this thread | | | Date | Tue, 25 Feb 2020 18:54:41 -0800 | From | Richard Cochran <> | Subject | Re: [RFC PATCH 0/2] AT8031 PHY timestamping support |
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On Wed, Feb 26, 2020 at 01:07:26AM +0100, Michael Walle wrote: > Am 26. Februar 2020 00:50:40 MEZ schrieb Andrew Lunn <andrew@lunn.ch>: > >That sounds fundamentally broken.
Right. It can't work unless the PHY latches the time stamp.
> This might be the case, but the datasheet (some older revision can > be found on the internet, maybe you find something) doesn't mention > it. Nor does the PTP "guide" (I don't know the exact name, I'd have > to check at work) of this PHY. Besides the timestamp there's also > the sequence number and the source port id which would need to be > read atomically together with the timestamp.
Maybe the part is not intended to be used at all in this way?
AFAICT, PHYs like this are meant to feed a "PTP frame detected" pulse into the time stamping unit on the attached MAC. The interrupt serves to allow the SW to gather the matching fields from the frame.
Thanks, Richard
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