problem about uart boot for am3358

Is this a custom board? What Linux version are you using?

Not  exactly, my  board is almost a am335x evm board.My MLO and u-boot and kernel works well, only when my board boots from uart , my u-boot cannot find nand flash. My linux version is v3.2 , all source code come from TI SDK.

Hi,

What command did you use to compile the U-Boot?

Sichao Tang said:

the u-boot alway told : no nand flash found!!

Did you mean "No NAND device found!!!" ? This will happen in the nand_scan_ident() function inside <u-boot_dir>/drivers/mtd/nand/nand_base.c, which scans for NAND devices. There is the following call:

    /* Read the flash type */
    type = nand_get_flash_type(mtd, chip, busw,
                &nand_maf_id, &nand_dev_id, table);

    if (IS_ERR(type)) {
#ifndef CONFIG_SYS_NAND_QUIET_TEST
        printk(KERN_WARNING "No NAND device found!!!\n");
#endif
        chip->select_chip(mtd, -1);
        return PTR_ERR(type);
    }

, which obviously returns an error. You need to check what type of error is returned from the nand_get_flash_type() function in order to analyse further.

Best regards,
Miroslav

I used the following command for compiling:

make O=am335x  am335x_evm

My  u-boot works well when my board booting from mmc or nand. Only when booting via uart, the u-boot cannot find nand flash.

The build command is correct.

Please print the return value of the nand_get_flash_type() function. Better yet, put some print statements before each return inside the nand_get_flash_type() function, so that we know what goes wrong with the NAND detection.

Best regards,
Miroslav

Hi,

I inserted some output statements inside nand_get_flash_type() function. And  it shows that ,when booting from NAND and MMC, the u-boot can grub the Manufacturer ID and Device ID correctly;But if I try to boot via UART,  the  Manufacturer ID and Device ID read by u-boot  are both ZERO. The logs are as following:

Booting from NAND:

Hi,

Please provide information about the state of your SYSBOOT pins (0-15) in both cases, NAND boot and UART boot? Are you only changing SYSBOOT pins 0-5 ?

Please also provide information about which processor pins are you connecting to the NAND flash? The WAIT signal?

Best regards,
Miroslav

My  SYSBOOT pins  from  bit 15 to bit 0 in both cases are 01000000 00000100. 

The information about processor pins connected to the NAND flash,Please check the pictures,as follows :

HI,

I solved this problem.

First , I must set  SYSBOOT pins (from  bit 15 to bit 0) as  01000000 00000001 ,but  no documents describe that  the SYSBOOT pins must be  setting as 01000000 00000001 ;

Second, I must wait for some 'C'  printed by the ROM code.  If there is no wait ,or if I finished setting Xmodem first ,then power on the board , although the u-boot can be loaded and run ,  the u-boot will find no NAND.

So, is this a bug? 

Thanks 

HI,

I have another question: SYSBOOT pins (from  bit 4 to bit 0) must be  00001 ?

If it's true, why there are so many boot settings which will boot via UART first? If false, I don't know what happened.

Would you please have a try on your GP EVM?Thank you!

Best regards

Hi,

Thank you!

I will try to find out the reasons.

Best regards,

Simon Tang