Re: aic7xxx broken in 2.6.18-rc3-mm2

[Daniel Ritz]

On Saturday 12 August 2006 20.05, Daniel Ritz wrote:
> On Saturday 12 August 2006 03.03, Greg KH wrote:
> > On Fri, Aug 11, 2006 at 05:36:24PM -0700, Andrew Morton wrote:
> > > On Fri, 11 Aug 2006 17:17:15 -0700
> > > Dave Hansen <haveblue@xxxxxxxxxx> wrote:
> > > 
> > > > Well, I have a new culprit of the hour:
> > > > 
> > > > 	gregkh-pci-pci-use-pci_bios-as-last-fallback
> > > 
> > > Thanks, I'll drop it.
> > > 
> > > > There was a previous patch that messed up a few of my machines and this
> > > > same driver a few months ago, which accounts for my sense of deja vu:
> > > > 
> > > > http://www.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.16-rc6/2.6.16-rc6-mm1/broken-out/gregkh-pci-pci-give-pci-config-access-initialization-a-defined-ordering.patch
> > 
> > Ugh, this is a mess.  Daniel, why does your machine need this patch, yet
> > as per Dave's comments, it's wrong?
> 
> it's not my machines. they work fine :) but there where bug reports on linux-pcmcia
> for this problem...only shows up with kernel >= 2.6.17. see also bug 6801.
> 
> 2.6.16 shows this:
> 	  PCI: PCI BIOS revision 2.10 entry at 0xfb9a0, last bus=0
> 	  PCI: Using configuration type 1
> while 2.6.17+ shows only
> 	  PCI: PCI BIOS revision 2.10 entry at 0xfb9a0, last bus=0
> 
> so accessing the cardbus cards is not possible with PCI BIOS but works
> just fine with direct access...
> 
> > 
> > I think it might come down to the fact that the ordering before used to
> > not always happen in the same order (it depended on config options and
> > linker luck.)  Now it's "fixed" to be the same way all the time.
> > Daniel, can't you solve this with the proper pci boot option?
> 
> sure, but the point is: it used to work on those boxes, but broke with 2.6.17
> 
> ok, i had a look. the problem is not the patch itself. look at arch/i386/pci/legacy.c
> it's where those messages come from:
> 	PCI: Probing PCI hardware
> 	PCI: Discovered peer bus 02
> 	PCI: Discovered peer bus 05
> 
> now if pcibios probing never runs pcibios_last_bus is -1 and pcibios_fixup_peer_bridges()
> exits immediatley, the other busses are never found...but why legacy probing anyway?
> 
anyway, this alternative patch should help. it should be more like the <= 2.6.16
behavior.

[ CC'ing Marcus Better as the tester of the original patch. ]

Marcus, could you test this patch instead of the original one and see how your
cardbus cards behave?

Dave, your SCSI card should work with this as well :)

with this patch my old toshiba laptop shows this in dmesg:
	PCI: PCI BIOS revision 2.10 entry at 0xf1987, last bus=21
	PCI: Using configuration type 1
ie. like kernel 2.6.16 and earlier...2.6.17+ would only show the pci bios line,
while with the earlier patch it only shows the type 1 line

rgds
-daniel

diff --git a/arch/i386/pci/init.c b/arch/i386/pci/init.c
index c7650a7..51087a9 100644
--- a/arch/i386/pci/init.c
+++ b/arch/i386/pci/init.c
@@ -14,8 +14,12 @@ #endif
 #ifdef CONFIG_PCI_BIOS
 	pci_pcbios_init();
 #endif
-	if (raw_pci_ops)
-		return 0;
+	/*
+	 * don't check for raw_pci_ops here because we want pcbios as last
+	 * fallback, yet it's needed to run first to set pcibios_last_bus
+	 * in case legacy PCI probing is used. otherwise detecting peer busses
+	 * fails.
+	 */
 #ifdef CONFIG_PCI_DIRECT
 	pci_direct_init();
 #endif

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