[PATCH] increase CARDBUS_MEM_SIZE

Linus sayeth:

Google knows everything, and finds, on MS own site no less:

  "Windows 2000 default resources:

   One 4K memory window

   One 2 MB memory window

   Two 256-byte I/O windows"

which is clearly utterly bogus and insufficient. But Microsoft apparently
realized this, and:

  "Windows XP default resources:

   Because one memory window of 4K and one window of 2 MB are not
   sufficient for CardBus controllers in many configurations, Windows XP
   allocates larger memory windows to CardBus controllers where possible.
   However, resource windows are static (that is, the operating system
   does not dynamically allocate larger memory windows if new devices
   appear.) Under Windows XP, CardBus controllers will be assigned the
   following resources:

   One 4K memory window, as in Windows 2000

   64 MB memory, if that amount of memory is available. If 64 MB is not
   available the controller will receive 32 MB; if 32 MB is not available,
   the controller will receive 16 MB; if 16 MB is not available, the
   bridge will receive 8 MB; and so on down to a minimum assignment of 1
   MB in configurations where memory is too constrained for the operating
   system to provide a larger window.

   Two 256-byte I/O windows"

So I think we have our answer. Windows uses one 4k window, and one 64MB
window. And they are no more dynamic than we are (we _could_ try to do it
dynamically, but let's face it, it's fairly painful to dynamically expand
PCI bus resources - you may need to reprogram everything up to the root,
so it would be absolutely crazy to do that unless you have some serious
masochistic tendencies).

So let's just increase our default value to 64M too.

Cc: Markus Rechberger <mrechberger@gmail.com>
Cc: Daniel Ritz <daniel.ritz@gmx.ch>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 8f7bcf56f1498d17064916d9986433e4e557631b..89f3036f0de8866d46081fca800e146c3376b32b 100644 (file)
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c
@@ -41,7 +41,7 @@
  * have a P2P bridge below a cardbus bridge, we need 4K.
  */
 #define CARDBUS_IO_SIZE                (256)
-#define CARDBUS_MEM_SIZE       (32*1024*1024)
+#define CARDBUS_MEM_SIZE       (64*1024*1024)
 
 static void __devinit
 pbus_assign_resources_sorted(struct pci_bus *bus)