source: trunk/target/linux/brcm47xx/patches-2.6.33/170-128MB_ram_bugfix.patch @ 20072

Last change on this file since 20072 was 20072, checked in by hauke, 7 years ago

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

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File size: 1.5 KB
  • arch/mips/bcm47xx/prom.c

    a b static __init void prom_init_cmdline(voi 
    126126static __init void prom_init_mem(void) 
    127127{ 
    128128        unsigned long mem; 
     129        unsigned long max; 
    129130 
    130131        /* Figure out memory size by finding aliases. 
    131132         * 
    static __init void prom_init_mem(void) 
    134135         * want to reuse the memory used by CFE (around 4MB). That means cfe_* 
    135136         * functions stop to work at some point during the boot, we should only 
    136137         * call them at the beginning of the boot. 
     138         *  
     139         * BCM47XX uses 128MB for addressing the ram, if the system contains 
     140         * less that that amount of ram it remaps the ram more often into the 
     141         * available space. 
     142         * Accessing memory after 128MB will cause an exception. 
     143         * max contains the biggest possible address supported by the platform. 
     144         * If the method wants to try something above we assume 128MB ram. 
    137145         */ 
     146        max = ((unsigned long)(prom_init) | ((128 << 20) - 1)); 
    138147        for (mem = (1 << 20); mem < (128 << 20); mem += (1 << 20)) { 
     148                if (((unsigned long)(prom_init) + mem) > max) { 
     149                        mem = (128 << 20); 
     150                        printk("assume 128MB RAM\n"); 
     151                        break; 
     152                } 
    139153                if (*(unsigned long *)((unsigned long)(prom_init) + mem) == 
    140154                    *(unsigned long *)(prom_init)) 
    141155                        break; 
    142156        } 
    143157 
    144         /* Ignoring the last page when ddr size is 128M. Cached 
    145          * accesses to last page is causing the processor to prefetch 
    146          * using address above 128M stepping out of the ddr address 
    147          * space. 
    148          */ 
    149         if (mem == 0x8000000) 
    150                 mem -= 0x1000; 
    151  
    152158        add_memory_region(0, mem, BOOT_MEM_RAM); 
    153159} 
    154160 
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