On Tue, Feb 26, 2013 at 1:08 PM, Benoît Thébaudeau benoit.thebaudeau@advansee.com wrote:
This boot pin / fuse config has been used by this driver for all i.MX platforms from the beginning. I don't think that we really need one more software config here. This is hardware stuff, and the i.MX provides a dedicated hardware configuration for it, so I think that we should use it, even if it's made for NAND boot, since it's just describing the present hardware, just like DT would.
In the particular case of the mx53ard, there is a DIP switch that you can use to fix this config to 8-bit NAND Flash. But if you have blown the fuses to override the boot pin config, then of course we're doomed because a wrong NAND Flash config has been blow.
The boot config jumpers are correctly set to boot from MMC card and this is what I am using as the boot media.
Why should we decide the NAND width via boot pins if I am not booting from NAND at all?
I see that current mxc nand drivers are doing like this, but I don't think this makes sense if we use NAND and does not boot from it.
I agree with this comment from tt01.h:
"/* * it's not 16 bit: * #define CONFIG_SYS_NAND_BUSWIDTH_16BIT * the current u-boot mxc_nand.c tries to auto-detect, but this only * reads the boot settings during reset (which might be wrong) */"
and we can also see the a workaround at board/davedenx/qong/qong.c in order to tell the nand bus width is 8 bits:
void qong_nand_plat_init(void *chip) { struct nand_chip *nand = (struct nand_chip *)chip; nand->chip_delay = 20; nand->select_chip = qong_nand_select_chip; nand->options &= ~NAND_BUSWIDTH_16; board_nand_setup(); }