Win 7 Legacy driver using wrong gap count

Discussion in 'Windows Vista Drivers' started by Paul, Aug 10, 2012.

  1. Paul

    Paul Guest

    I have a Win7x64 systems that is under-performing from a 1394 standpoint. That is, the device is working fine until I start to push the bus throughput close to it capabilities, then data loss occurs (buffer overflows). If Itry a different 1394a adapter on the same system, it works fine. I used a1394 bus analyzer, and I see that my problem seems to be rooted in the gapcount that the 1394 bus controller is choosing; it’s using the maximum (and default) value of 63, even though it’s a point-to-point connection (with a reasonable length cable). The working adapter will set the gap countto 10 or 11. The bus is not capable of chaieving the throughput I need with this very 'relaxed' setting for the gap count

    In both cases, I’m using the legacy driver (as this is the one qualified for this system).

    Is there some way I can configure this system to use a shorter gap count? I could use a SET_LOCAL_HOST_PROPERTIES_GAP_COUNT, but that will only set the lower bound to allow long cables – I would need an upper bound limit to ensure the necessary bus performance. I also found this reference


    which sets the StaticGapCount/GapCountMethod registry entries, but that didnot work – the host controller still uses a gap count of 63.

    Any ideas?


    Paul, Aug 10, 2012
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