hi, I am sorry to send unreadable mail so many times.I want to try again. Now ,the u-boot can work well ,but the i can not controlethcad cs8900 very well.i can not read the id of cs8900.I have ported the blob to mx1ads ,and i can get the id of cs8900 .now ,i just copy the code in blob to u-boot to get the id of cs8900 ,but i am failed .I do not know why . the code related to is as follows : //set CS4U *(volatile unsigned long*)(0x00220020) = 0x00000F00; //set CS4L control register *(volatile unsigned long*)(0x00220024) = 0x80001501; //set the GPIO muxing to use Chip Select 4 *(volatile unsigned long*)(0x0021C020) &= 0xFF3FFFFF; *(volatile unsigned long*)(0x0021C038) &= 0xFF3FFFFF; //the irq is connect to GPIO pin to PortC pin 17 *((volatile unsigned long* ) 0x0021c220)&=~0x00020000; *((volatile unsigned long*) 0x0021c238)&=~0x00020000; //send the base address of cs8900 on the ADD Bus c = *(volatile unsigned char *)(0x15000300); CS8900_PPTR = regno; printf("CS8900_PDATA = %x\n",CS8900_PDATA);

the result is always 0x5555,i do not know why,these codes above can work well in blob. I am looking forward your reply,thank ahead!