TI CardBus bridge problem

[Greg KH]

On Sun, Jul 03, 2005 at 09:40:09PM +0100, Russell King wrote:
> On Sun, Jul 03, 2005 at 08:45:11PM +0200, Dominik Brodowski wrote:
> > Hi,
> > 
> > Please try this patch:
> > 
> > http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/patches/pci/pci-fix-routing-in-parent-bridge.patch
> 
> I don't think this patch should be used - there is no guarantee that
> there aren't any PCI busses numbered after the one which has the cardbus
> bridge on, so this patch could result in other PCI busses becoming
> unaccessible.

I've held off on this patch for a number of months now, but I know 2
distros have been shipping it for quite some time (suse and gentoo) and
it fixes real problems.  It's also lived in the -mm tree for quite some
time with no complaints.

> We're gaining an ever increasing number of platforms which have this
> Cardbus-related problem, and so far "pci=assign-busses" has fixed
> each one apparantly without additional complaints.

I think Andi has hardware that this patch was necessary for, which
"assign-busses" did not fix the issue.  Andi?

> However, for a bullet proof fix, what I think needs doing is:
> 
> * at boot, store the original bus configuration.
> * always do the pci=assign-busses thing.
> * use the original bus configuration when looking up IRQ resources and
>   the like in ACPI/PIRQ/whatever.
> * restore the bus configuration when we reboot/halt.
> 
> However, we may or may not need the last step, but I suspect some x86
> BIOS won't like to warm-reboot without it.

I imagine some will not like that at all.  But I like the idea.  Now if
only someone had the time to implement it :(

thanks,

greg k-h