[mcnet4l-devel] 21554 configuration access

[Daniel S. <st...@in...>]

mark,

is it possible to query the whole primary side, ie. backplane topology
(devid,vendor,bars, etc) from the seconday side of a 21554?

i've been playing around with the 21554's configuration transaction
generation feature for the last 3 hours or so, but not being very
successful. may be due to my lack of experience with configuration
accesses:

say, i'd like to simply generate a type 1 configuration like this:
(bus << 16) | (dev << 11) | (fn << 8) | (reg & ~3) | 1 )

would this work? 
i (believe to) understand how pci bridges forward type 1 cycles to
subordinate buses, checking primary/secondary/subordinat number, finally
converting them to type 0, fine. however, i'm asking because i'm not
sure whether e.g. the opposite direction, i.e. backplane-to-lower-busnr
works.
right now, a'll i'm reading are tons of 0xFFF..'s :)

so is this simply not possible or am i just not getting the trick?

i thought i could use this information in order to optimise upstream
memory mappings for the drawbridge driver throgh simply reading bar
contents. besides, in order to run SNs on an embedded bridge, the
discovery stuff would need such a feature anyway.
ideally, i would be able to generate an image of the whole shared bus
topology.

regards,
dns

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