Re: fast ethernet driver MII phy serial clock rates

From: David Burns (david.burns_at_dugeem.net)
Date: 04/25/04

  • Next message: David Burns: "Re: fast ethernet driver MII phy serial clock rates" 
    Date: Sun, 25 Apr 2004 23:10:55 +1000
To: Andre Oppermann <andre@freebsd.org>

    Andre Oppermann wrote:
    >
    > This is a very interesting observation. I've just worked my way through
    > the MII code to add link state notification to the routing socket and had
    > to remove a couple of return(0) when the link is up to break so the later
    > status function can read the MII and announce the state change if neccessary.
    > Based on your explanation this seems to be a regression and I will look at
    > how to work around this.
    >
    > Do you have any idea how to make the MII access faster or to get some sort
    > of async notification from the hardware when the link state changes so we
    > don't have to poll every second?
    >

    Apart from cautiously removing the DELAY(1) and retesting each driver on
    a few different hardware platforms there are a couple of other small
    improvements that could be considered:

    1. Not all PHYs need resyncing on every operation - which would
    obviously eliminate half the access time
    2. Only do autoneg operations every 10 seconds (although I think 17 is
    the current period for MII autoneg timeout?) - at least this will help
    minimise per second operations.

    A handful of PHYs appear to support a form of link state interrupt but
    given it hasn't already been implemented I'm suspecting broken hardware
    - not to mention the additional driver complexity necessary for a small
    gain.

    David

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