Re: Configuring synchronous ethernet with ethtool?

[Ben Hutchings <ben@decadent.org.uk>]

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On Sat, 2015-04-04 at 22:03 +0200, Richard Cochran wrote:
> On Sat, Apr 04, 2015 at 02:59:10PM +0100, Ben Hutchings wrote:
> > The 'manual' setting matches terminology in IEEE 802.3 (section 40.5.2).
> > There's no mention of 'preferred' there but perhaps this switch will
> > claim to be a single-port if you say it should prefer slave mode.
> 
> Thanks for the reference.  The switch I was talking about has control
> register 9 implemented exactly as described in 802.3, but the TRM
> description of bit 9.10 adds the word "prefer".
> 
> > So, I like the idea but it should not be tied to SyncE only.
> 
> Something like this?
> 
>    | ethtool property        | effect             |
>    |-------------------------+--------------------|
>    | synce-mode = none       | 9.12 = 0           |

That's not 'none', it's just not forced.  This would be used for both
asynchronous operation and for synchronous operation with negotiated
clock mode.

>    | synce-mode = master     | 9.12 = 1, 9.11 = 1 |
>    | synce-mode = slave      | 9.12 = 1, 9.11 = 0 |

So there are four different modes that should be selectable through
ethtool:

- Asynchronous [100BASE-T only]
- Synchronous, automatic
- Synchronous, master
- Synchronous, slave

>    | port-type = multiport   | 9.10 = 1           |
>    | port-type = single-port | 9.10 = 0           |

For backward compatibility ethtool would also need to be able to report
'unknown' when the kernel or driver doesn't support this.

Ben.

-- 
Ben Hutchings
The most exhausting thing in life is being insincere. - Anne Morrow Lindberg

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