How to block pci config-reads during device self-test?

[Benjamin Herrenschmidt]

> I'm not sure what's doing the config-spcae reads ... seems to be some
> user-space tool or daemon.  I'm wondering if there is any practical
> way to block such reads to a given device until its self-test
> sequence is completed.  I could try to modify the architecture-specific
> pci files to do this (arch/ppc64/kernel/pSeries_pci.c) but this seems
> a tad ugly ... is there another way?  or do we have to just learn to
> live with this ahrdware?

I see no sane solution... I have a similar (not exactly identical though)
problem on the g5 where some devices will lockup on config access when
they are power managed. What I did there was to hack a list of devices
to "ignore" on config accesses...

If your driver knows when the device is going away for the BIST and how
long, maybe you can play tricks like adding a property to the device
node indicating if the device should be skipped on config access (that
is basically return all fffffff's), have the driver set that for
the duration of the BIST, and the config ops check that.

Definitely not the cleanest way, but to me, it seems like broken HW...

Ben.

** Sent via the linuxppc64-dev mail list. See http://lists.linuxppc.org/