brcm-2.4: fix commit r18413 "128MB ram problem"

This was missing in commit r20072

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@20651 3c298f89-4303-0410-b956-a3cf2f4a3e73

diff --git a/target/linux/brcm-2.4/files/arch/mips/bcm947xx/prom.c b/target/linux/brcm-2.4/files/arch/mips/bcm947xx/prom.c
index f635b4a..c974574 100644 (file)
--- a/target/linux/brcm-2.4/files/arch/mips/bcm947xx/prom.c
+++ b/target/linux/brcm-2.4/files/arch/mips/bcm947xx/prom.c
@@ -21,25 +21,32 @@ void __init
 prom_init(int argc, const char **argv)
 {
        unsigned long mem;
+       unsigned long max;
 
         mips_machgroup = MACH_GROUP_BRCM;
         mips_machtype = MACH_BCM947XX;
 
-       /* Figure out memory size by finding aliases */
+       /* Figure out memory size by finding aliases
+        * 
+        * BCM47XX uses 128MB for addressing the ram, if the system contains
+        * less that that amount of ram it remaps the ram more often into the
+        * available space.
+        * Accessing memory after 128MB will cause an exception.
+        * max contains the biggest possible address supported by the platform.
+        * If the method wants to try something above we assume 128MB ram.
+        */
+       max = ((unsigned long)(prom_init) | ((128 << 20) - 1));
        for (mem = (1 << 20); mem < (128 << 20); mem += (1 << 20)) {
+               if (((unsigned long)(prom_init) + mem) > max) {
+                       mem = (128 << 20);
+                       printk("assume 128MB RAM\n");
+                       break;
+               }
                if (*(unsigned long *)((unsigned long)(prom_init) + mem) == 
                    *(unsigned long *)(prom_init))
                        break;
        }
 
-       /* Ignoring the last page when ddr size is 128M. Cached
-        * accesses to last page is causing the processor to prefetch
-        * using address above 128M stepping out of the ddr address
-        * space.
-        */
-       if (mem == 0x8000000)
-               mem -= 0x1000;
-
        add_memory_region(0, mem, BOOT_MEM_RAM);
 }