[PATCH] [MTD] [NAND] nand_base.c: reset chip first

[Karl Beldan]

Some chips require a RESET after power-up (e.g. Micron MT29FxGxxxxx).
The first command sent is NAND_CMD_READID.
Issue a NAND_CMD_RESET in nand_scan_ident before reading the device id.
Tested with an MT29F4G08AAC.

Signed-off-by: Karl Beldan <karl.beldan at gmail.com>
---
Prior to resetting, the chip gives a correct first ID byte though.


diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index d1129ba..2cfac9b 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2318,6 +2318,12 @@ static struct nand_flash_dev
*nand_get_flash_type(struct mtd_info *mtd,
 	/* Select the device */
 	chip->select_chip(mtd, 0);

+	/*
+	 * Reset the chip, required by some chips (e.g. Micron MT29FxGxxxxx)
+	 * after power-up
+	 */
+	chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);
+
 	/* Send the command for reading device ID */
 	chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);

@@ -2488,6 +2494,8 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips)
 	/* Check for a chip array */
 	for (i = 1; i < maxchips; i++) {
 		chip->select_chip(mtd, i);
+		/* See comment in nand_get_flash_type for reset */
+		chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);
 		/* Send the command for reading device ID */
 		chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
 		/* Read manufacturer and device IDs */