diff options
| author | Brian Norris <computersforpeace@gmail.com> | 2014-05-06 00:46:17 +0530 |
|---|---|---|
| committer | Tom Rini <trini@ti.com> | 2014-06-06 17:46:03 -0400 |
| commit | 27ce9e4290b168a1241699d411678959aaf9649b (patch) | |
| tree | 7f341734dddc4a061058efa5a297461d99b53afa /drivers/mtd/nand/am335x_spl_bch.c | |
| parent | b9ae609fdbb7f8149a13bb9c67006b7237cbf83e (diff) | |
mtd: nand: force NAND_CMD_READID onto 8-bit bus
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>
Diffstat (limited to 'drivers/mtd/nand/am335x_spl_bch.c')
| -rw-r--r-- | drivers/mtd/nand/am335x_spl_bch.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/mtd/nand/am335x_spl_bch.c b/drivers/mtd/nand/am335x_spl_bch.c index bd89b067d5..ce65d8e12b 100644 --- a/drivers/mtd/nand/am335x_spl_bch.c +++ b/drivers/mtd/nand/am335x_spl_bch.c @@ -55,7 +55,7 @@ static int nand_command(int block, int page, uint32_t offs, } /* Shift the offset from byte addressing to word addressing. */ - if (this->options & NAND_BUSWIDTH_16) + if ((this->options & NAND_BUSWIDTH_16) && !nand_opcode_8bits(cmd)) offs >>= 1; /* Set ALE and clear CLE to start address cycle */ |