> > But it looks like buffer 1 is used for data with large page flash.
> >
>
> Well, we save first word of the buffer and then recover it.
So then there's no longer any special reason to use buffer 1 for status,
and that comment is misleading...
> +static u_char mxc_nand_read_byte(struct mtd_info *mtd)
> +{
> + struct nand_chip *nand_chip = mtd->priv;
> + struct mxc_nand_host *host = nand_chip->priv;
> + uint8_t ret = 0;
> + uint16_t col, rd_word;
> + uint16_t __iomem *main_buf =
> + (uint16_t __iomem *)host->regs->main_area0;
> + uint16_t __iomem *spare_buf =
> + (uint16_t __iomem *)host->regs->spare_area0;
> +
> + /* Check for status request */
> + if (host->status_request)
> + return get_dev_status(host) & 0xFF;
> +
> + /* Get column for 16-bit access */
> + col = host->col_addr >> 1;
> +
> + /* If we are accessing the spare region */
> + if (host->spare_only)
> + rd_word = readw(&spare_buf[col]);
> + else
> + rd_word = readw(&main_buf[col]);
> +
> + /* Pick upper/lower byte of word from RAM buffer */
> + if (host->col_addr & 0x1)
> + ret = (rd_word >> 8) & 0xFF;
> + else
> + ret = rd_word & 0xFF;
Use a union, as in read_buf(). Otherwise, this breaks on big-endian --
you may not care, but it's better to not have such dependencies lurking
in the code that could be reused who-knows-where.
> + if (col & 1) {
> + rd_word = readw(p);
> + ret = (rd_word >> 8) & 0xff;
> + rd_word = readw(&p[1]);
> + ret |= (rd_word << 8) & 0xff00;
Again, this is unnecessary, but if you insist, use a union.
> +#ifdef CONFIG_MTD_NAND_MXC_FORCE_CE
> + if (chip > 0) {
> + MTDDEBUG(MTD_DEBUG_LEVEL0,
> + "ERROR: Illegal chip select (chip = %d)\n", chip);
If it's an error, that's not exactly debug (especially since there's no
way to propagate the error upwards)...
> + return;
> + }
> +
> + if (chip == -1) {
> + writew(readw(&host->regs->nfc_config1) & ~NFC_CE,
> + &host->regs->nfc_config1);
> + return;
> + }
> +
> + writew(readw(&host->regs->nfc_config1) | NFC_CE,
> + &host->regs->nfc_config1);
> +#endif
#else?
> + if (column >= mtd->writesize) {
> + /*
> + * before sending SEQIN command for partial write,
> + * we need read one page out. FSL NFC does not support
> + * partial write. It alway send out 512+ecc+512+ecc ...
> + * for large page nand flash. But for small page nand
> + * flash, it does support SPARE ONLY operation.
> + */
> + if (host->pagesize_2k) {
> + /* call ourself to read a page */
> + mxc_nand_command(mtd, NAND_CMD_READ0, 0,
> + page_addr);
> + }
#ifdef CONFIG_MXC_NAND_HWECC?
> + /* 50 us command delay time */
> + this->chip_delay = 5;
5 or 50?
> + host->pagesize_2k = 0;
Make this board-configurable. Has large page been tested? If not,
perhaps it should stay out for now, given how weird it is on this
controller.
-Scott