brcm47xx: fix commit r18413 "128MB ram problem"

The patch commited in r18413 was wrong.
This patch prevents prom_init_mem from scanning over 128MB ram.
This is from #6765 and #3177

Refresh all patches


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@20072 3c298f89-4303-0410-b956-a3cf2f4a3e73

1 files changed, 45 insertions, 0 deletions

diff --git a/target/linux/brcm47xx/patches-2.6.33/170-128MB_ram_bugfix.patch b/target/linux/brcm47xx/patches-2.6.33/170-128MB_ram_bugfix.patch
new file mode 100644
index 0000000000..9819ad7115
--- /dev/null
+++ b/target/linux/brcm47xx/patches-2.6.33/170-128MB_ram_bugfix.patch
@@ -0,0 +1,45 @@
+--- a/arch/mips/bcm47xx/prom.c
++++ b/arch/mips/bcm47xx/prom.c
+@@ -126,6 +126,7 @@ static __init void prom_init_cmdline(voi
+ static __init void prom_init_mem(void)
+ {
+ 	unsigned long mem;
++	unsigned long max;
+ 
+ 	/* Figure out memory size by finding aliases.
+ 	 *
+@@ -134,21 +135,26 @@ static __init void prom_init_mem(void)
+ 	 * want to reuse the memory used by CFE (around 4MB). That means cfe_*
+ 	 * functions stop to work at some point during the boot, we should only
+ 	 * call them at the beginning of the boot.
++	 * 
++	 * 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);
+ }
+