Re: SCSI QLA not working on latest *-mm SN2

James Bottomley
2004-09-21T16:11:55Z

On Tue, 2004-09-21 at 12:05, Jesse Barnes wrote:
> Reading from the closest bridge won't be enough? If not, then dealing with
> posting in a nice way is simply impossible for some devices. We'd be stuck
> with udelay().

That's correct. The posted write is held somewhere in one of the
bridges, but the PCI ordering rules only require it to be ordered with
other MMIO reads to the *device*; so you only guarantee that the posted
write is flushed by doing a device read....obviously, there exist
bridges with looser ideas than this, but we need to follow the PCI
specs.

udelay() isn't a viable solution because the PCI specs have no upper
bound on the length of time a write may remain posted.

James