[PATCH] yenta: fix hidden PCI bus numbers
authorBernhard Kaindl <bk@suse.de>
Tue, 30 May 2006 16:00:34 +0000 (18:00 +0200)
committerDominik Brodowski <linux@dominikbrodowski.net>
Fri, 30 Jun 2006 20:09:09 +0000 (22:09 +0200)
Fixup the subordinate number parent bridge of yenta Cardbus Bridges
before the PCI bus scan starts to make the cardbus cards which are
otherwise hidden for PCI scans work.

Signed-off-by: Bernhard Kaindl <bk@suse.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
drivers/pcmcia/yenta_socket.c

index 006749d..d9d005e 100644 (file)
@@ -1005,6 +1005,77 @@ static void yenta_config_init(struct yenta_socket *socket)
        config_writew(socket, CB_BRIDGE_CONTROL, bridge);
 }
 
+/**
+ * yenta_fixup_parent_subordinate - Fix subordinate bus# of the parent bridge
+ * @cardbus_bridge: The PCI bus which the CardBus bridge bridges to
+ *
+ * Checks if devices on the bus which the CardBus bridge bridges to would be
+ * invisible during PCI scans because of a misconfigured subordinate number
+ * of the parent brige - some BIOSes seem to be too lazy to set it right.
+ * Does the fixup carefully by checking how far it can go without conflicts.
+ * See http://bugzilla.kernel.org/show_bug.cgi?id=2944 for more information.
+ */
+static void yenta_fixup_parent_bridge(struct pci_bus *cardbus_bridge)
+{
+       struct list_head *tmp;
+       unsigned char upper_limit;
+       /*
+        * We only check and fix the parent bridge: All systems which need
+        * this fixup that have been reviewed are laptops and the only bridge
+        * which needed fixing was the parent bridge of the CardBus bridge:
+        */
+       struct pci_bus *bridge_to_fix = cardbus_bridge->parent;
+
+       /* Check bus numbers are already set up correctly: */
+       if (bridge_to_fix->subordinate >= cardbus_bridge->subordinate)
+               return; /* The subordinate number is ok, nothing to do */
+
+       if (!bridge_to_fix->parent)
+               return; /* Root bridges are ok */
+
+       /* stay within the limits of the bus range of the parent: */
+       upper_limit = bridge_to_fix->parent->subordinate;
+
+       /* check the bus ranges of all silbling bridges to prevent overlap */
+       list_for_each(tmp, &bridge_to_fix->parent->children) {
+               struct pci_bus * silbling = pci_bus_b(tmp);
+               /*
+                * If the silbling has a higher secondary bus number
+                * and it's secondary is equal or smaller than our
+                * current upper limit, set the new upper limit to
+                * the bus number below the silbling's range:
+                */
+               if (silbling->secondary > bridge_to_fix->subordinate
+                   && silbling->secondary <= upper_limit)
+                       upper_limit = silbling->secondary - 1;
+       }
+
+       /* Show that the wanted subordinate number is not possible: */
+       if (cardbus_bridge->subordinate > upper_limit)
+               printk(KERN_WARNING "Yenta: Upper limit for fixing this "
+                       "bridge's parent bridge: #%02x\n", upper_limit);
+
+       /* If we have room to increase the bridge's subordinate number, */
+       if (bridge_to_fix->subordinate < upper_limit) {
+
+               /* use the highest number of the hidden bus, within limits */
+               unsigned char subordinate_to_assign =
+                       min(cardbus_bridge->subordinate, upper_limit);
+
+               printk(KERN_INFO "Yenta: Raising subordinate bus# of parent "
+                       "bus (#%02x) from #%02x to #%02x\n",
+                       bridge_to_fix->number,
+                       bridge_to_fix->subordinate, subordinate_to_assign);
+
+               /* Save the new subordinate in the bus struct of the bridge */
+               bridge_to_fix->subordinate = subordinate_to_assign;
+
+               /* and update the PCI config space with the new subordinate */
+               pci_write_config_byte(bridge_to_fix->self,
+                       PCI_SUBORDINATE_BUS, bridge_to_fix->subordinate);
+       }
+}
+
 /*
  * Initialize a cardbus controller. Make sure we have a usable
  * interrupt, and that we can map the cardbus area. Fill in the
@@ -1120,6 +1191,8 @@ static int __devinit yenta_probe (struct pci_dev *dev, const struct pci_device_i
        yenta_get_socket_capabilities(socket, isa_interrupts);
        printk(KERN_INFO "Socket status: %08x\n", cb_readl(socket, CB_SOCKET_STATE));
 
+       yenta_fixup_parent_bridge(dev->subordinate);
+
        /* Register it with the pcmcia layer.. */
        ret = pcmcia_register_socket(&socket->socket);
        if (ret == 0) {