CardBus support on G3 Blue&White

Russell King rmk+pcmcia at
Sun May 23 17:01:56 EDT 2004

On Sun, May 23, 2004 at 04:20:02PM -0400, Pavel Roskin wrote:
> 16-bit PCMCIA are working just fine.  However, the CardBus card is not
> detected.  There are no error messages in the kernel log.  The card just
> doesn't appear in the lspci output.

Basically, the configuration cycles can't reach the other side
of the cardbus bridge.  Let's look at the topology of the PCI bus.
The important lines are these:

0000:00:0d.0 PCI bridge: Digital Equipment Corporation DECchip 21154 (rev 02) (prog-if 00 [Normal decode])
	Bus: primary=00, secondary=01, subordinate=01, sec-latency=32

0000:01:02.0 CardBus bridge: Texas Instruments PCI1410 PC card Cardbus Controller (rev 01)
	Bus: primary=01, secondary=02, subordinate=05, sec-latency=176

So, we have:

     bus 0-n       bus 1-1         bus 2-5
HOST---------21154---------Cardbus---------Cardbus card

where "bus A-B" means that the bus carries configuration cycles for
bus numbers between A and B inclusive.  I think you can see the
problem immediately from that - the 21154 is only programmed to
forward configuration cycles for bus 1, but the cardbus card is
on bus 2.  Configuration cycles for bus 2 will never reach the
cardbus bridge let alone the cardbus card itself.

Please report this to the PowerPC people - its a PCI bus setup problem
not a Cardbus problem.  Maybe they can provide some input (and maybe
even say whether its possible to change the PCI bus configuration so
it actually works.)

Russell King
 Linux kernel    2.6 ARM Linux   -
 maintainer of:  2.6 PCMCIA      -
                 2.6 Serial core

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