[U-Boot] [U-Boot, v5, 2/5] mtd: nand: force NAND_CMD_READID onto 8-bit bus

[Tom Rini <trini@ti.com>]

On Tue, May 06, 2014 at 12:46:17AM +0530, pekon gupta wrote:

> From: Brian Norris <computersforpeace@gmail.com>
> 
> As per following Sections in ONFI Spec, NAND_CMD_READID should use only
> lower 8-bit for transfering command, address and data even on x16 NAND device.
> 
> *Section: Target Initialization"
> "The Read ID and Read Parameter Page commands only use the lower 8-bits of the
>  data bus. The host shall not issue commands that use a word data width on x16
>  devices until the host determines the device supports a 16-bit data bus width
>  in the parameter page."
> 
> *Section: Bus Width Requirements*
> "When the host supports a 16-bit bus width, only data is transferred at the
>  16-bit width. All address and command line transfers shall use only the lower
>  8-bits of the data bus. During command transfers, the host may place any value
>  on the upper 8-bits of the data bus. During address transfers, the host shall
>  set the upper 8-bits of the data bus to 00h."
> 
> Thus porting  following commit from linux-kernel to ensure that column address
> is not altered to align to x16 bus when issuing NAND_CMD_READID command.
> 
>     commit 3dad2344e92c6e1aeae42df1c4824f307c51bcc7
>     mtd: nand: force NAND_CMD_READID onto 8-bit bus
>     Author: Brian Norris <computersforpeace@gmail.com> (preserving authorship)
> 
>     The NAND command helpers tend to automatically shift the column address
>     for x16 bus devices, since most commands expect a word address, not a
>     byte address. The Read ID command, however, expects an 8-bit address
>     (i.e., 0x00, 0x20, or 0x40 should not be translated to 0x00, 0x10, or
>     0x20).
> 
>     This fixes the column address for a few drivers which imitate the
>     nand_base defaults.
> 
> Signed-off-by: Pekon Gupta <pekon@ti.com>

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

-- 
Tom
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