時鐘修改

vim arch/arm/cpu/arm920t/start.S

# if defined(CONFIG_S3C2410) || defined(CONFIG_S3C2440)
        ldr     r1, =0x3ff
        ldr     r0, =INTSUBMSK
        str     r1, [r0]
        
        /* FCLK:HCLK:PCLK = 1:2:4 */
        /* default FCLK is 120 MHz ! */
        ldr     r0, =CLKDIVN
        mov     r1, #
 
5
        str     r1, [r0]

        /* add by Flinn */
                #define S3C2440_MPLL_200MHZ     ((0x5c<<12)|(0x01<<4)|(0x02))
                #define S3C2440_MPLL_400MHZ     ((0x5c<<12)|(0x01<<4)|(0x01))

        mrc     p15, 0, r1, c1, c0, 0   
        orr     r1, r1, #0xc0000000
        mcr     p15, 
 
0, r1, c1, c0, 0

        /* MPLLCON = S3C2440_MPLL_400MHZ */
        ldr r0, =0x4c000004
        ldr r1, =S3C2440_MPLL_400MHZ
        str r1, [r0]

SDRAM設定

vim board/samsung/smdk2440/lowlevel_init.S
    #define REFCNT                  1113   -> 0x4f4

時鐘前面設定了， 刪除後面的

vim board/samsung/smdk2440/smdk2440.c
board_early_init_f（）：
 
#if 0
            /* to reduce PLL lock time, adjust the LOCKTIME register */
            writel(0xFFFFFF, &clk_power->locktime);
    
            /* configure MPLL */
            writel((M_MDIV << 12) + (M_PDIV << 4) + M_SDIV,
                   &clk_power->mpllcon);
    
            /* some delay between MPLL and UPLL */
            pll_delay(4000);
    
            /* configure UPLL */
            writel((U_M_MDIV << 12) + (U_M_PDIV << 4) + U_M_SDIV,
                   &clk_power->upllcon);
#endif

再次燒寫

U-Boot 2014.10 (Nov 01 2018 - 11:06:54)
            
            CPUID: 32440001
            FCLK:      400 MHz
            HCLK:      100 MHz
            PCLK:       50 MHz
            DRAM:  64 MiB
            WARNING: Caches not enabled
            Flash: *** failed ***
            ### ERROR ### Please RESET the board ###

原因是

board_init_r
                flash_init 此時我們的nor flash還不識別
                去掉
                else {
                    puts(failed);
                    //hang();
                }

重新編譯燒寫

U-Boot 2014.10 (Nov 01 2018 - 11:14:31)

        CPUID: 32440001
        FCLK:      400 MHz
        HCLK:      100 MHz
        PCLK:       50 MHz
        DRAM:  64 MiB
        WARNING: Caches not enabled
        Flash: *** failed ***
        *** Warning - bad CRC, using default environment
        
        In:    serial
        Out:   serial
        Err:   serial
        Net:   CS8900-0
        Error: CS8900-0 address not set.
        
        Warning: Your board does not use generic board. Please read
        doc/README.generic-board and take action. Boards not
        upgraded by the late 2014 may break or be removed.