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Commit c47cc20c authored by Hauke Mehrtens's avatar Hauke Mehrtens Committed by John Crispin
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MIPS: BCM47XX: improve memory size detection 



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: default avatarHauke Mehrtens <hauke@hauke-m.de>
Patchwork: http://patchwork.linux-mips.org/patch/4362


Signed-off-by: default avatarJohn Crispin <blogic@openwrt.org>
parent d3dce3d6

arch/mips/bcm47xx/prom.c

+6 −4
Original line number Diff line number Diff line 
/*

 *  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;

	}