mtd: omap: fix subpage ecc issue with prefetch

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=c5d8c0cae4af7d78823d32fcd1c458ee1a1b5489
Commit:     c5d8c0cae4af7d78823d32fcd1c458ee1a1b5489
Parent:     61cc8276fa776ced06b0e5b67b57e12c4997d388
Author:     Kishore Kadiyala <kishore.kadiyala at ti.com>
AuthorDate: Wed May 11 21:17:27 2011 +0530
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Wed May 25 02:03:37 2011 +0100

    mtd: omap: fix subpage ecc issue with prefetch
    
    When reading/writing a subpage (When HW ECC is not available/enabled)
    for number of bytes not aligned to 4, the mis-aligned bytes are handled
    first (by cpu copy method) before enabling the Prefetch engine to/from
    'p'(start of buffer 'buf'). Then it reads/writes rest of the bytes with
    the help of Prefetch engine, if available, or again using cpu copy method.
    Currently, reading/writing of rest of bytes, is not done correctly since
    its trying to read/write again to/from begining of buffer 'buf',
    overwriting the mis-aligned bytes.
    
    Read & write using prefetch engine got broken in commit '2c01946c'.
    We never hit a scenario of not getting 'gpmc_prefetch_enable' call
    success. So, problem did not get caught up.
    
    Signed-off-by: Kishore Kadiyala <kishore.kadiyala at ti.com>
    Signed-off-by: Vimal Singh <vimal.newwork at gmail.com>
    Reported-by: Bryan DE FARIA <bdefaria at adeneo-embedded.com>
    Cc: stable at kernel.org [2.6.35+]
    Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 drivers/mtd/nand/omap2.c |   12 +++++-------
 1 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 288423f..39f46a0 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -263,11 +263,10 @@ static void omap_read_buf_pref(struct mtd_info *mtd, u_char *buf, int len)
 	if (ret) {
 		/* PFPW engine is busy, use cpu copy method */
 		if (info->nand.options & NAND_BUSWIDTH_16)
-			omap_read_buf16(mtd, buf, len);
+			omap_read_buf16(mtd, (u_char *)p, len);
 		else
-			omap_read_buf8(mtd, buf, len);
+			omap_read_buf8(mtd, (u_char *)p, len);
 	} else {
-		p = (u32 *) buf;
 		do {
 			r_count = gpmc_read_status(GPMC_PREFETCH_FIFO_CNT);
 			r_count = r_count >> 2;
@@ -293,7 +292,7 @@ static void omap_write_buf_pref(struct mtd_info *mtd,
 						struct omap_nand_info, mtd);
 	uint32_t w_count = 0;
 	int i = 0, ret = 0;
-	u16 *p;
+	u16 *p = (u16 *)buf;
 	unsigned long tim, limit;
 
 	/* take care of subpage writes */
@@ -309,11 +308,10 @@ static void omap_write_buf_pref(struct mtd_info *mtd,
 	if (ret) {
 		/* PFPW engine is busy, use cpu copy method */
 		if (info->nand.options & NAND_BUSWIDTH_16)
-			omap_write_buf16(mtd, buf, len);
+			omap_write_buf16(mtd, (u_char *)p, len);
 		else
-			omap_write_buf8(mtd, buf, len);
+			omap_write_buf8(mtd, (u_char *)p, len);
 	} else {
-		p = (u16 *) buf;
 		while (len) {
 			w_count = gpmc_read_status(GPMC_PREFETCH_FIFO_CNT);
 			w_count = w_count >> 1;