mtd: nand: don't use read_buf for 8-bit ONFI transfers

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=bd9c6e99b58255b9de1982711ac9487c9a2f18be
Commit:     bd9c6e99b58255b9de1982711ac9487c9a2f18be
Parent:     3dad2344e92c6e1aeae42df1c4824f307c51bcc7
Author:     Brian Norris <computersforpeace at gmail.com>
AuthorDate: Fri Nov 29 22:04:28 2013 -0800
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Mon Mar 10 22:42:23 2014 -0700

    mtd: nand: don't use read_buf for 8-bit ONFI transfers
    
    Use a repeated read_byte() instead of read_buf(), since for x16 buswidth
    devices, we need to avoid the upper I/O[16:9] bits. See the following
    commit for reference:
    
    commit 05f7835975dad6b3b517f9e23415985e648fb875
    Author: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
    Date:   Thu Dec 5 22:22:04 2013 +0100
    
        mtd: nand: don't use {read,write}_buf for 8-bit transfers
    
    Now, I think that all barriers to probing ONFI on x16 devices are
    removed, so remove the check from nand_flash_detect_onfi().
    
    Tested on 8-bit ONFI NAND (Micron MT29F32G08CBADAWP).
    
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
    Tested-by: Ezequiel Garcia <ezequiel.garcia at free-electrons.com>
    Tested-By: Pekon Gupta <pekon at ti.com>
---
 drivers/mtd/nand/nand_base.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 6281151..79ed8cc 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3065,7 +3065,7 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
 					int *busw)
 {
 	struct nand_onfi_params *p = &chip->onfi_params;
-	int i;
+	int i, j;
 	int val;
 
 	/* Try ONFI for unknown chip or LP */
@@ -3074,18 +3074,10 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
 		chip->read_byte(mtd) != 'F' || chip->read_byte(mtd) != 'I')
 		return 0;
 
-	/*
-	 * ONFI must be probed in 8-bit mode or with NAND_BUSWIDTH_AUTO, not
-	 * with NAND_BUSWIDTH_16
-	 */
-	if (chip->options & NAND_BUSWIDTH_16) {
-		pr_err("ONFI cannot be probed in 16-bit mode; aborting\n");
-		return 0;
-	}
-
 	chip->cmdfunc(mtd, NAND_CMD_PARAM, 0, -1);
 	for (i = 0; i < 3; i++) {
-		chip->read_buf(mtd, (uint8_t *)p, sizeof(*p));
+		for (j = 0; j < sizeof(*p); j++)
+			((uint8_t *)p)[j] = chip->read_byte(mtd);
 		if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) ==
 				le16_to_cpu(p->crc)) {
 			break;