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DDR在DTS中配置mem=256Mb导致mem报错解决DDR大小识别错误

2022-10-22
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mem报错解决DDR大小识别错误

一、问题描述

通过DTS文件配置DDR大小,发现在DTS中配置DDR为256Mb编译出来的固件,在DDR为128Mb的硬件中固件启动之后会造成mem报错,导致系统重启。

二、解决方法

通过查看linux kernel中arch/mips/ralink/of.c文件的plat_mem_setup()函数,发现如果DTS文件中没有配置DDR大小,系统则会自动识别DDR大小

void __init plat_mem_setup(void)
{
    void *dtb = NULL;

    set_io_port_base(KSEG1);

    /*  
     * Load the builtin devicetree. This causes the chosen node to be
     * parsed resulting in our memory appearing. fw_passed_dtb is used
     * by CONFIG_MIPS_APPENDED_RAW_DTB as well.
     */
    if (fw_passed_dtb)
        dtb = (void *)fw_passed_dtb;
    else if (__dtb_start != __dtb_end)
        dtb = (void *)__dtb_start;

    __dt_setup_arch(dtb);

    strlcpy(arcs_cmdline, boot_command_line, COMMAND_LINE_SIZE);

    of_scan_flat_dt(early_init_dt_find_memory, NULL);
    if (memory_dtb)
        of_scan_flat_dt(early_init_dt_scan_memory, NULL);
    else if (soc_info.mem_detect)
        soc_info.mem_detect();
    else if (soc_info.mem_size)
        add_memory_region(soc_info.mem_base, soc_info.mem_size * SZ_1M,
                  BOOT_MEM_RAM);
    else
        detect_memory_region(soc_info.mem_base,
                     soc_info.mem_size_min * SZ_1M,
                     soc_info.mem_size_max * SZ_1M);
}

所以在DTS中将mem的配置节点删除,重新编译固件,固件就可以实现DDR自适应

@@ -13,11 +13,6 @@
                led-upgrade = &led_run;
        };
 
-       memory@0 {
-               device_type = "memory";
-               reg = <0x0 0x8000000>;
-       };
-
        chosen {
                bootargs = "console=ttyS0,115200";
        };

三、使用uboot bootargs传参

openwrt1907默认关闭了uboot传参,并给kernel cmdline设了一个固定值,make kernel_menuconfig选上MIPS_CMDLINE_FROM_BOOTLOADER

Symbol: MIPS_CMDLINE_FROM_BOOTLOADER [=y]                                                                                                                                                              │  
  │ Type  : boolean                                                                                                                                                                                        │  
  │ Prompt: Bootloader kernel arguments if available                                                                                                                                                       │  
  │   Location:                                                                                                                                                                                            │  
  │     -> Kernel type                                                                                                                                                                                     │  
  │ (1)   -> Kernel command line type (<choice> [=y])                                                                                                                                                      │  
  │   Defined at arch/mips/Kconfig:2993                                                                                                                                                                    │  
  │   Depends on: <choice>

再通过修改arch/mips/ralink/of.c文件将strlcpy(arcs_cmdline, boot_command_line, COMMAND_LINE_SIZE)屏蔽,这样kernel就会默认从uboot的bootargs中获取参数,重新编译固件

     __dt_setup_arch(dtb);

-    strlcpy(arcs_cmdline, boot_command_line, COMMAND_LINE_SIZE);
+    //strlcpy(arcs_cmdline, boot_command_line, COMMAND_LINE_SIZE);

     of_scan_flat_dt(early_init_dt_find_memory, NULL);
     if (memory_dtb)
         of_scan_flat_dt(early_init_dt_scan_memory, NULL);

uboot在bootargs中设置mem=128m(这里只设置mem,还有其他参数根据实际情况设置)

MT7621 # setenv bootargs mem=128m
MT7621 # saveenv
Saving Environment to SPI Flash...
Erasing SPI Flash...
.
Writing to SPI Flash...
.
done
MT7621 # printenv
bootcmd=tftp
bootdelay=7
baudrate=115200
ethaddr="00:AA:BB:CC:DD:10"
ipaddr=192.168.1.1
serverip=192.168.1.2
uboot_name=uboot-gl-mt1300.bin
firmware_name=openwrt-gl-mt1300.bin
lc=if ping $serverip; then tftp 0x81000000 config.bin && cp.b 0xbc40000 0x81100000 0xffff && cp 0x81000000 0x81100000 0x40 && cp.b 0x81000000 0x81101002 0x06 && erase 0xbc040000 +0xffff && cp 0x81000000 0xbc040000 0xffff; fi
lu=if ping $serverip; then tftp 0x81000000 $uboot_name && erase 0xbc000000 +0x40000 && cp $fileaddr 0xbc000000 $filesize && echo OK!; else echo ERROR! Server not reachable!; fi
lf=if ping $serverip; then tftp 0x81000000 $firmware_name && erase 0xbc050000 +$filesize && cp $fileaddr 0xbc050000 $filesize && echo OK!; else echo ERROR! Server not reachable!; fi
BootType=3
aaa=bbb
stdin=serial
stdout=serial
stderr=serial
bootargs=mem=128m

Environment size: 838/4092 bytes
MT7621 # reset

kernel启动日志:

[    0.000000] Linux version 4.14.171 (deng@ubuntu) (gcc version 7.5.0 (OpenWrt GCC 7.5.0 r10947-65030d81f3)) #0 SMP Thu Feb 27 21:05:12 2020
[    0.000000] SoC Type: MediaTek MT7621 ver:1 eco:3
[    0.000000] bootconsole [early0] enabled
[    0.000000] CPU0 revision is: 0001992f (MIPS 1004Kc)
[    0.000000] MIPS: machine is GL-MT1300
[    0.000000] Determined physical RAM map:
[    0.000000]  memory: 10000000 @ 00000000 (usable)      #DTS设置DDR为256Mb
[    0.000000] User-defined physical RAM map:
[    0.000000]  memory: 08000000 @ 00000000 (usable)      #通过获取bootargs参数修改DDR为128Mb
[    0.000000] Initrd not found or empty - disabling initrd
[    0.000000] VPE topology {2,2} total 4
[    0.000000] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    0.000000] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    0.000000] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    0.000000] Zone ranges:
[    0.000000]   Normal   [mem 0x0000000000000000-0x0000000007ffffff]
[    0.000000]   HighMem  empty
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000000000000-0x0000000007ffffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x0000000007ffffff]
[    0.000000] random: get_random_bytes called from start_kernel+0x94/0x4a8 with crng_init=0
[    0.000000] percpu: Embedded 14 pages/cpu s26192 r8192 d22960 u57344
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 32512
[    0.000000] Kernel command line:  console=ttyS0,115200 mem=128m rootfstype=squashfs,jffs2 #kernel cmdline发现mem=128m传参成功

这样也可以解决DDR大小识别错误问题


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于2022-10-22发布
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