Messages in this thread | | | Date | Thu, 9 Nov 2000 01:03:36 +0300 | From | Ivan Kokshaysky <> | Subject | Re: PCI-PCI bridges mess in 2.4.x |
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On Wed, Nov 08, 2000 at 09:37:44AM -0800, Richard Henderson wrote: > Interesting. I hadn't known that. It didn't actually fail with > the ALI bridge, I just assumed it was a mistake. Can anyone with > docs on non-DEC bridges confirm that this is a common thing?
It would be better if someone who has "PCI-to-PCI Bridge Architecture Specification" handy could confirm this. Non-conforming hardware must live in quirks/fixups etc. ;-)
I've found some interesting info today - application note on programming the DEC 21052 bridge (ruffian has this chip, btw): http://download.sourceforge.net/mirrors/NetBSD/misc/dec-docs/ec-qlzba-te.ps.gz
Particularly, there are examples for setting up that bridge for IO or MEM only configurations. For example, with IO disabled: 1. Set IO base = 0xffff, limit = 0 2. Set command register = PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER
> Certainly the fact should be commented if the old code goes back > in to avoid disruption by helpful folks like myself. :-)
That change wasn't bad at all - at least it's 100% safe :-) But of course, it would be better to have unused regions disabled in a clean way.
But actually I'm concerned that all this code doesn't work at all - see reports from Michal Jaegermann (the bridge acts as if it drops config space transactions randomly). I have a lot of suggestions, but it's a pain to debug something without access to real hardware - just a waste of the precious time of everyone who is involved... So I would probably wait a week or two until I'll have something with bridges :-(
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