[U-Boot] [U-Boot, v5, 4/5] mtd: nand: omap: add CONFIG_SYS_NAND_BUSWIDTH_16BIT to indicate NAND device bus-width

[Tom Rini]

On Tue, May 06, 2014 at 12:46:19AM +0530, pekon gupta wrote:

> GPMC controller needs to be configured based on bus-width of the NAND device
> connected to it. Also, dynamic detection of NAND bus-width from on-chip ONFI
> parameters is not possible in following situations:
> SPL:    SPL NAND drivers does not support ONFI parameter reading.
> U-boot: GPMC controller iniitalization is done in omap_gpmc.c:board_nand_init()
>         which is called before probing for devices, hence any ONFI parameter
>         information is not available during GPMC initialization.
> 
> Thus, OMAP NAND driver expected board developers to explicitely write GPMC
> configurations specific to NAND device attached on board in board files itself.
> But this was troublesome for board manufacturers as they need to dive into
> lengthy platform & SoC documents to find details of GPMC registers and
> appropriate configurations to get NAND device working.
> 
> This patch instead adds existing CONFIG_SYS_NAND_BUSWIDTH_16BIT to board config
> hich indicates that connected NAND device has x16 bus-width. And then based on
> this config GPMC driver itself initializes itself based on NAND bus-width. This
> keeps board developers free from knowing GPMC controller specific internals.
> 
> Signed-off-by: Pekon Gupta <pekon at ti.com>

Applied to u-boot-ti/master, thanks!

-- 
Tom
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