EZSDK_5_04 U-BOOT NAND ERR

Hello Haoran Li, 

I am facing similar problems with my DM8148. So I've already encountered your bug. I have traced it down to a code change in the following file: 

ezsdk_5_04_00_11/board-support/u-boot-2010.06-psp04.04.00.01/arch/arm/cpu/arm_cortexa8/ti81xx/sys_info.c

It appears that the return values in the funtion u32 get_sysboot_bw(void) have been swapped (as compared to EZSDK 5.03). That is, a 16-bit NAND is set as 8-bit and vise versa. If you swap it back to the way it is in EZSDK 5.03, this error appears to go away.

However, after doing this I run into another problem where the MLO has problem reading NAND when booting the 2nd stage u-boot. My serial terminal shows this:

U-Boot 2010.06-svn49 (May 24 2012 - 12:52:02)

TI8148-GP rev 2.1

ARM clk: 600MHz
DDR clk: 400MHz

DRAM: 2 GiB
NAND: HW ECC BCH8 Selected
256 MiB
Using default environment

The 2nd stage U-Boot will now be auto-loaded
Please do not interrupt the countdown till TI8148_EVM prompt if 2nd stage is already flashed
Hit any key to stop autoboot: 0

NAND read: device 0 offset 0x20000, size 0x60000
ECC: uncorrectable.
ECC: uncorrectable.
.................
<insert many more lines of "ECC: uncorrectable." here>
.................
ECC: uncorrectable.
ECC: uncorrectable.

NAND read from offset 2000
393216 bytes read: ERROR

So I am still trying to figure out what the root of the problem is and whether my first change was the correct one. Any additional help would be appreciated.

After doing a bit more digging, it appears that u-boot in EZSDK 5.04 has changed the default NAND ECC mode set to BCH8. This used to only apply to MLO in 5.03, but now it looks like U-Boot uses it by default. Which explains why my working EZSDK 5.03 system would report "ECC: uncorrectable." errors after updating it with the MLO generated by EZSDK 5.04.

I found that the second last line of code in function int board_nand_init(struct nand_chip *nand) from "ezsdk/board-support/u-boot-2010.06-psp04.04.00.01/drivers/mtd/nand/ti81xx_nand.c" was changed from: 

ti81xx_nand_switch_ecc(NAND_ECC_HW, 0); in EZSDK 5.03

to 

ti81xx_nand_switch_ecc(NAND_ECC_HW, 2); in EZSDK 5.04

which appears to change the default ECC mode from Hamming to BCH8

My first attempt at a solution was to run "nandecc hw 2" before I "nand write.i" any U-Boot image and before I do a "saveenv". This allowed me to load both MLO, U-Boot 2nd stage and read ENV variables without ECC problems.

However, when I tried to load the Linux kernel, I got "ECC: uncorrectable." again. I tried writing the Linux kernel to NAND using BCH8, but there were a lot of ECC read errors when loading.

So, I am getting closer, but I still don't quite have a working system booting from NAND that is build by EZSDK 5.04

Hi Nicholas,

Have you figured this out this out? I've almost solved the problem with BCH8. Still some more work is left. 

Yes, my last post was to say that I had figured it out. 

Hi Renjith,

I have similar problem http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/375822.aspx were you able to fix it ?

Thanks & Regards

Mike