Pekon!
On 04.12.2013 13:15, Gupta, Pekon wrote:
Very strangely, the Technexion TAO3530 board works fine with SPL. Even with current mainline. The only difference I can see right now is, that TAO3530 has an 16bit NAND chip and the CM_T35 has an 8bit NAND chip.
For HAM1_HW this selects ecc-scheme as below.. @@omap_select_ecc_scheme() case OMAP_ECC_HAM1_CODE_HW:
/* define ecc-layout */ecclayout->eccbytes = nand->ecc.bytes * eccsteps;for (i = 0; i < ecclayout->eccbytes; i++)ecclayout->eccpos[i] = i + BADBLOCK_MARKER_LENGTH;ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH;ecclayout->oobfree[0].length = oobsize - ecclayout->eccbytes -BADBLOCK_MARKER_LENGTH;Aah!!... May be I understand the issue.. Reference: As per OMAP3530 TRM given below http://www.ti.com/product/omap3530 http://www.ti.com/litv/pdf/spruf98x Chapter-25: Initialization Sub-topic: Memory Booting Section: 25.4.7.4 NAND Figure 25-19. ECC Locations in NAND Spare Areas For large-page NAND (a) x8 Device: ECC signature starts from byte[1] in OOB (offset of 1 *byte*) (b) x16 Device: ECC signature starts from byte[2] in OOB (offset of 1 *word*)
And in omap_gpmc.c .. BADBLOCK_MARKER_LENGTH = 2. So ECC signature starts from offset ecclayout->eccpos[0] = 0 + BADBLOCK_MARKER_LENGTH = 0x2; which is actually for (b) that is x16 device.
Thus, Technexion TAO3530 board with x16 NAND device is booting correctly, Whereas CM_T35 with x8 NAND device fails..
Sounds like a very good explanation. Thanks!
Unfortunately I have to stop debugging this issue now. Perhaps Pekon has an idea on whats going on here. Pekon, do you have an OMAP3530 board with an 8bit NAND chip? Or do you have any other idea, what might cause this problem?
It's a bug in driver. I should have taken care of device-width while defining the layout. I think this is the issue with HAM1 scheme only, because ROM code has same ecc-layout for other schemes (like BCH8) whether it's a x8 or x16 devices. Please patch following to see if CM_T35 boots fine, with latest u-boot.
diff --git a/drivers/mtd/nand/omap_gpmc.c b/drivers/mtd/nand/omap_gpmc.c index bf43520..99dfcc6 100644 --- a/drivers/mtd/nand/omap_gpmc.c +++ b/drivers/mtd/nand/omap_gpmc.c @@ -626,7 +626,10 @@ static int omap_select_ecc_scheme(struct nand_chip *nand, /* define ecc-layout */ ecclayout->eccbytes = nand->ecc.bytes * eccsteps; for (i = 0; i < ecclayout->eccbytes; i++)
ecclayout->eccpos[i] = i + BADBLOCK_MARKER_LENGTH;
if (nand->options & NAND_BUSWIDTH_16)ecclayout->eccpos[i] = i + 2;elseecclayout->eccpos[i] = i + 1; ecclayout->oobfree[0].offset = i + BADBLOCK_MARKER_LENGTH; ecclayout->oobfree[0].length = oobsize - ecclayout->eccbytes - BADBLOCK_MARKER_LENGTH;Thanks for pointing out this.. Sorry I don't have many OMAP3 boards to boot-test HAM1, so this error crept in. Once you confirm its working, I'll submit a formal patch.
Yes. This fixes this issue on the cm-t35 board. So please submit a proper patch. :)
Thanks again for this quick fix! Stefan