[openib-general] Race in mthca_cmd_post()

[chas williams - CONTRACTOR]

In message <adawt743syo.fsf at cisco.com>,"Roland Dreier" writes:
>saying that a read of PCI MMIO space is racing with a write -- and I
>would have thought that a read has to flush all posted writes.

a read does flush all the posted writes but that doesnt mean that
the write operation has had enough time to "complete".

i had a similar problem on the altix platform with posted writes.
part of the hw init was to write the reset register, wait a few ticks,
and then read the register until you saw a flag clear.  reading the
device "too soon" failed because it was in some poor state that didnt
respond properly.  with posted writes, you needed to force out the writes
(not using read obviously) and then wait the appropriate time.