openwrtv4/target/linux/xburst/patches-3.18/002-NAND-Optimize-NAND_ECC_HW_OOB_FIRST-read.patch

From 98d33db1c87e2447b9b203399d2f995e05ecdb52 Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen <lars@metafoo.de>
Date: Sat, 26 Feb 2011 15:30:07 +0100
Subject: [PATCH 2/7] NAND: Optimize NAND_ECC_HW_OOB_FIRST read

Avoid sending unnecessary READ commands to the chip.
---
 drivers/mtd/nand/nand_base.c |   17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1360,9 +1360,16 @@ static int nand_read_page_hwecc_oob_firs
 	unsigned int max_bitflips = 0;
 
 	/* Read the OOB area first */
-	chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
-	chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
-	chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);
+	/* Read the OOB area first */
+	if (mtd->writesize > 512) {
+		chip->cmdfunc(mtd, NAND_CMD_READ0, mtd->writesize, page);
+		chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
+		chip->cmdfunc(mtd, NAND_CMD_RNDOUT, 0, -1);
+	} else {
+		chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
+		chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
+		chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);
+	}
 
 	for (i = 0; i < chip->ecc.total; i++)
 		ecc_code[i] = chip->oob_poi[eccpos[i]];
@@ -1575,7 +1582,9 @@ static int nand_do_read_ops(struct mtd_i
 						 __func__, buf);
 
 read_retry:
-			chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
+			if (chip->ecc.mode != NAND_ECC_HW_OOB_FIRST) {
+				chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
+			}
 
 			/*
 			 * Now read the page into the buffer.  Absent an error,