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Commit c5d8c0ca authored by Kishore Kadiyala's avatar Kishore Kadiyala Committed by David Woodhouse
Browse files

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: default avatarKishore Kadiyala <kishore.kadiyala@ti.com>
Signed-off-by: default avatarVimal Singh <vimal.newwork@gmail.com>
Reported-by: default avatarBryan DE FARIA <bdefaria@adeneo-embedded.com>
Cc: stable@kernel.org [2.6.35+]
Signed-off-by: default avatarArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent 61cc8276

drivers/mtd/nand/omap2.c

+5 −7
Original line number Diff line number Diff line
@@ -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;