2440 2.6.27启动后主频405Mhz却打印出来是571Mhz

2.6.27
网上有人一样是启动时乱码，他说修改时钟频率为12M就可以了，我的板子本来就是12M晶振
我是临时通过屏蔽内核串口设置来去掉乱码的，下面有正确做法
drivers/serial/samsung.c中8个wr_regl 函数屏蔽掉
core 571.536 MHz，确实是主时钟错了，有点离谱，bootloader里的时钟是405M，启动后不修改uart设置，能正常显示打印，说明这时时钟还是405MHZ。虽然是主频导致uart计算波特率的divider出错导致的乱码，但是为什么会到571Mhz呢？

这样我启动后看到的打印是：
enter Main
cp15 register 1 = c000107c
************************************
* *
* 2440 bootloader *
* Nov 17 2008,11:22:08 *
* *
************************************
Read chip id = ec76
Nand flash status = c0
NAND_Read addr : 40000, size : 1c0000
................................................................................................................Uncompressing Linux.................................................................................................................. done, booting the kernel.
Linux version 2.6.27 (root@sherman_samba) (gcc version 3.4.1) #4 Tue Nov 18 11:51:27 CST 2008
CPU: ARM920T [41129200] revision 0 (ARMv4T), cr=c0007177
Machine: SMDK2440
ATAG_INITRD is deprecated; please update your bootloader.
Memory policy: ECC disabled, Data cache writeback
CPU S3C2440A (id 0x32440001)
S3C244X: core 571.536 MHz, memory 142.884 MHz, peripheral 71.442 MHz
S3C24XX Clocks, (c) 2004 Simtec Electronics
CLOCK: Slow mode (2.116 MHz), fast, MPLL on, UPLL on
CPU0: D VIVT write-back cache
CPU0: I cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
CPU0: D cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 16256
Kernel command line: noinitrd root=/dev/mtdblock2 init=/linuxrc console=ttySAC0,115200
irq: clearing subpending status 00000092
PID hash table entries: 256 (order: 8, 1024 bytes)
timer tcon=00000000, tcnt e88e, tcfg 00000200,00000000, usec 00001580
Console: colour dummy device 80x30
console [ttySAC0] enabled
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Memory: 64MB = 64MB total
Memory: 61120KB available (3256K code, 322K data, 144K init)
Calibrating delay loop... 285.08 BogoMIPS (lpj=712704)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
net_namespace: 440 bytes
NET: Registered protocol family 16
S3C2410 Power Management, (c) 2004 Simtec Electronics
S3C2440: Initialising architecture
S3C2440: IRQ Support
S3C24XX DMA Driver, (c) 2003-2004,2006 Simtec Electronics
DMA channel 0 at c4800000, irq 33
DMA channel 1 at c4800040, irq 34
DMA channel 2 at c4800080, irq 35
DMA channel 3 at c48000c0, irq 36
S3C244X: Clock Support, DVS off
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 2048 (order: 2, 16384 bytes)
TCP bind hash table entries: 2048 (order: 1, 8192 bytes)
TCP: Hash tables configured (established 2048 bind 2048)
TCP reno registered
NET: Registered protocol family 1
NetWinder Floating Point Emulator V0.97 (extended precision)
JFFS2 version 2.2. (NAND) (SUMMARY) © 2001-2006 Red Hat, Inc.
msgmni has been set to 119
io scheduler noop registered
io scheduler anticipatory registered (default)
io scheduler deadline registered
io scheduler cfq registered
Console: switching to colour frame buffer device 30x40
fb0: s3c2410fb frame buffer device
lp: driver loaded but no devices found
ppdev: user-space parallel port driver
Serial: 8250/16550 driver4 ports, IRQ sharing enabled
s3c2440-uart.0: s3c2410_serial0 at MMIO 0x50000000 (irq = 70) is a S3C2440
s3c2440-uart.1: s3c2410_serial1 at MMIO 0x50004000 (irq = 73) is a S3C2440
s3c2440-uart.2: s3c2410_serial2 at MMIO 0x50008000 (irq = 76) is a S3C2440
brd: module loaded
loop: module loaded
dm9000 Ethernet Driver, V1.31
Uniform Multi-Platform E-IDE driver
Driver 'sd' needs updating - please use bus_type methods
S3C24XX NAND Driver, (c) 2004 Simtec Electronics
60 ns is too big for current clock rate 142884
s3c2440-nand s3c2440-nand: cannot get suitable timings
s3c2440-nand: probe of s3c2440-nand failed with error -22
usbmon: debugfs is not available
s3c2410-ohci s3c2410-ohci: S3C24XX OHCI
s3c2410-ohci s3c2410-ohci: new USB bus registered, assigned bus number 1
s3c2410-ohci s3c2410-ohci: irq 42, io mem 0x49000000
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 2 ports detected
usbcore: registered new interface driver libusual
usbcore: registered new interface driver usbserial
usbserial: USB Serial support registered for generic
usbcore: registered new interface driver usbserial_generic
usbserial: USB Serial Driver core
usbserial: USB Serial support registered for FTDI USB Serial Device
usbcore: registered new interface driver ftdi_sio
ftdi_sio: v1.4.3:USB FTDI Serial Converters Driver
usbserial: USB Serial support registered for pl2303
usbcore: registered new interface driver pl2303
pl2303: Prolific PL2303 USB to serial adaptor driver
mice: PS/2 mouse device common for all mice
S3C24XX RTC, (c) 2004,2006 Simtec Electronics
s3c2440-i2c s3c2440-i2c: slave address 0x10
s3c2440-i2c s3c2440-i2c: bus frequency set to 372 KHz
s3c2440-i2c s3c2440-i2c: i2c-0: S3C I2C adapter
S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics
s3c2410-wdt s3c2410-wdt: watchdog inactive, reset disabled, irq enabled
TCP cubic registered
NET: Registered protocol family 17
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
drivers/rtc/hctosys.c: unable to open rtc device (rtc0)
Root-NFS: No NFS server available, giving up.
VFS: Unable to mount root fs via NFS, trying floppy.
VFS: Cannot open root device "mtdblock2" or unknown-block(2,0)
Please append a correct "root=" boot option; here are the available partitions:
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)
========================
时钟不对，连nand都不能正常操作
------->>>>
s3c244x.c s3c244x_init_clocks
------->>>>
cpu.c static struct cpu_table cpu_ids[] __initdata
------->>>>
cpu.c s3c24xx_init_clocks
------->>>>
mach-smdk2440.c smdk2440_map_io
该函数中带了时钟输入参数
s3c24xx_init_clocks(16934400);
因为我们用的晶振是12M的，所以需要改成下面这样
s3c24xx_init_clocks(12000000);

这样串口也正常了，时钟也对了，nand也对了