NAND 16 bit buswidth issue

I am running U-boot 2009.08 on a sequoia based custom board. The board has a Micron 29F2G16AAD nand chip. This chip is a large page device with a 16 bit buswidth. I have an issue in nand_base.c in the nand_get_flash_type function where the check for buswidth fails, causing the print out -

printk(KERN_WARNING "NAND bus width %d instead %d bit\n",

                       (chip->options & NAND_BUSWIDTH_16) ? 16 : 8,
                       busw ? 16 : 8);

The busw is read from the nand chip and is correct, but the
chip->options is incorrect. I don't see where this gets set to the
options shown in nand_ids.c. I see that here:

        /* Lookup the flash id */
        for (i = 0; nand_flash_ids[i].name != NULL; i++) {
                if (dev_id == nand_flash_ids[i].id) {
                        type =  &nand_flash_ids[i];
                        break;
                }
        }

type gets the correct values from nand_ids, should the value of type->options be assigned to chip->options? Or am I missing something and need to set chip->options somewhere in my board specific files?

The controller driver is supposed to set chip->options.

-Scott

The controller driver being used is ndfc.c, it doesn't set the
options though. From what I can tell, nand.c calls nand_scan without actually setting the nand options. I have been setting chip->options to include NAND_BUSWIDTH_16, but want to move all my changes back to board specific code to eventually submit for review.

/* Lookup the flash id */

        for (i = 0; nand_flash_ids[i].name != NULL; i++) {
                if (dev_id == nand_flash_ids[i].id) {
                        type =  &nand_flash_ids[i];
                        break;
                }
        }

        if (!type)
                return ERR_PTR(-ENODEV);

        if (!mtd->name)
                mtd->name = type->name;

        chip->chipsize = type->chipsize << 20;

Since type is set to the options read from nand_flash_ids in the
nand_get_flash_type function, would it be appropriate to just set chip->options to type->options as is done with the chipsize? If not, what would be the most acceptable way to do this?

The controller driver isn't sufficiently board-specific, so you want to change the generic code instead? :-)

The problem with autodetection is that you need to issue accesses to the chip in order to read the ID data. What word size are you going to use to make *those* accesses? Maybe doing 8-bit accesses happens to work well enough for ID on your 16-bit chip and controller combination, but that's not something we can assume generically.

Find a way to have your board config file tell the controller driver what bus width to specify.

-Scott