I have issues handling DBBT at absolute page in u-boot. The requirement is U-boot should use DBBT written by kobs-ng to check block good or bad before performing the operation(read/write/erase) on it
instead of scanning all blocks and creating its own table.
Using kobs-ng tool, We can write redundant copy of FCB, DBBT and firmware at first partition of NAND. I can also see DBBT having some entries for bad block that was found scanning NAND in my platform.
Following are kobs-ng code snap shot that write FCB, DBBT and DBBT Entries for Bad block.
Using above code FCBs are written in block 0, 1, 2 and 3. DBBTs are written in block 4,5,6 and 7 of NAND chip.
In u-boot, I configured nand option as follow
init board_nand_init(struct nand_chip *nand)
{
….
nand->options |= NAND_USE_FLASH_BBT | NAND_USE_FLASH_BBT_NO_OOB ;
….
}
and
static struct nand_bbt_descr bbt_main_no_bbt_descr = {
.options = NAND_BBT_ABSPAGE | NAND_BBT_WRITE
| NAND_BBT_4BIT
| NAND_BBT_NO_OOB,
.len = 4,
.veroffs = 8,
.maxblocks = 4,
.pattern = bbt_pattern,
.pages[0]=512, /* Block 4 in Page */
};
Now I expect DBBT is read from page 512 (block 4) and should match pattern “bbt_pattern” and should have version number at Offset of 8 as shown below.
When U-boot is booting up, DBBT at page 512 is read in function read_abs_bbts(…) in nand_bbt.c and read buffer is sent to read_bbt(…).
In read_bbt(…) function, I don’t see the code to match finger print, read version number and read DBBT entries for bad block.
Instead In read_bbt(…) , All blocks are scanned again for bad block mark again.
I want to understand how DBBT at absolute page is handled and used in u-boot.
Cheers
Gnana
