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SubjectPATCH: Fix CardBus bridge behind a PCI bridge
On Mon, Aug 12, 2002 at 12:21:58PM -0700, dhinds wrote:
> On Mon, Aug 12, 2002 at 11:29:11AM -0700, H. J. Lu wrote:
> >
> > > what does "positive decode" mean in this context? Does the bridge
> > > somehow figure out that if no other device claims a transaction, that
> > > it should do so?
> >
> > I am not a PCI expert. As I understand, if a PCI bridge does negative
> > decode, you don't need to do it for the CardBus bride behind it. I
> > guess it is only needed for positive decode. For some reason, a PCI
> > bridge with positive decode may pass address to the CardBus bridge
> > behind it or the CardBus bridge has some back door to the PCI bus.
>
> I pulled up the datasheet for this chip and now I think maybe I
> understand what's going on.
>
> It says that the PCI-to-PCI bridge function in this chip forwards all
> transactions to the external PCI bus. The bridge windows determine
> ranges of addresses which it may claim back as a target, in this case
> I guess just for the LAN function, which is the only integrated device
> on bus 2.
>
> So this actually seems to be effectively a transparent bridge.
>

How about this pacth? It works for me.


H.J.
--- linux/drivers/pcmcia/yenta.c.bridge Sat Aug 10 20:30:35 2002
+++ linux/drivers/pcmcia/yenta.c Mon Aug 12 14:00:38 2002
@@ -706,7 +706,8 @@ static int yenta_suspend(pci_socket_t *s

static void yenta_allocate_res(pci_socket_t *socket, int nr, unsigned type)
{
- struct pci_bus *bus;
+ struct pci_bus *bus, *parent;
+ struct pci_dev *bridge;
struct resource *root, *res;
u32 start, end;
u32 align, size, min, max;
@@ -739,17 +740,43 @@ static void yenta_allocate_res(pci_socke
return;
}

- align = size = 4*1024*1024;
- min = PCIBIOS_MIN_MEM; max = ~0U;
if (type & IORESOURCE_IO) {
align = 1024;
size = 256;
min = 0x4000;
max = 0xffff;
}
+ else {
+ align = size = 4*1024*1024;
+ min = PCIBIOS_MIN_MEM;
+ max = ~0U;
+ }

- if (allocate_resource(root, res, size, min, max, align, NULL, NULL) < 0)
+
+ /* We check if we are behind an Intel 82801BAM/CAM PCI bridge
+ which is a transparent bridge for us. We just allocate
+ resources from its parent. */
+ parent = bus->parent;
+ if (parent != NULL) {
+ bridge = parent->self;
+ if (bridge != NULL
+ && (bridge->class >> 8) == PCI_CLASS_BRIDGE_PCI
+ && bridge->vendor == PCI_VENDOR_ID_INTEL
+ && bridge->device >= PCI_DEVICE_ID_INTEL_82801BA_0
+ && bridge->device <= PCI_DEVICE_ID_INTEL_82801BA_11) {
+ res->name = bridge->subordinate->name;
+ root = pci_find_parent_resource(bridge, res);
+ }
+ }
+
+ if (allocate_resource(root, res, size, min, max, align, NULL, NULL) < 0) {
+ printk (KERN_NOTICE "PCI: CardBus bridge (%04x:%04x, %04x:%04x): Failed to allocate %s resource: %d bytes!\n",
+ socket->dev->vendor, socket->dev->device,
+ socket->dev->subsystem_vendor,
+ socket->dev->subsystem_device,
+ (type & IORESOURCE_IO) ? "I/O" : "memory", size);
return;
+ }

config_writel(socket, offset, res->start);
config_writel(socket, offset+4, res->end);
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