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MIPS: BCM47XX: improve memory size detection

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The memory size is detected by finding a place where it repeats in
memory. Currently we are just checking when the function prom_init is
seen again, but it is better to check for a bigger part of the memory
to decrease the chance of wrong results.

This should fix a problem we saw in OpenWrt, where the detected
available memory decreed on some devices when doing a soft reboot.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Patchwork: http://patchwork.linux-mips.org/patch/4362
Signed-off-by: John Crispin <blogic@openwrt.org>
This commit is contained in:
Hauke Mehrtens 2012-10-03 11:34:17 +00:00 committed by John Crispin
parent d3dce3d676
commit c47cc20ca5
1 changed files with 6 additions and 4 deletions
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10
arch/mips/bcm47xx/prom.c
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@ -1,6 +1,7 @@
/*
* Copyright (C) 2004 Florian Schirmer <jolt@tuxbox.org>
* Copyright (C) 2007 Aurelien Jarno <aurelien@aurel32.net>
* Copyright (C) 2010-2012 Hauke Mehrtens <hauke@hauke-m.de>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
@ -128,6 +129,7 @@ static __init void prom_init_mem(void)
{
unsigned long mem;
unsigned long max;
unsigned long off;
struct cpuinfo_mips *c = &current_cpu_data;
/* Figure out memory size by finding aliases.
@ -145,15 +147,15 @@ static __init void prom_init_mem(void)
* 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));
off = (unsigned long)prom_init;
max = off | ((128 << 20) - 1);
for (mem = (1 << 20); mem < (128 << 20); mem += (1 << 20)) {
if (((unsigned long)(prom_init) + mem) > max) {
if ((off + mem) > max) {
mem = (128 << 20);
printk(KERN_DEBUG "assume 128MB RAM\n");
break;
}
if (*(unsigned long *)((unsigned long)(prom_init) + mem) ==
*(unsigned long *)(prom_init))
if (!memcmp(prom_init, prom_init + mem, 32))
break;
}