[MTD] [NAND] fsl_elbc_nand: workaround for hangs during nand write

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=0ff6631be150702ed4c92b46b77941affee866ba
Commit:     0ff6631be150702ed4c92b46b77941affee866ba
Parent:     93919d384df98eba02bebd417ecb2f481b3bdcb8
Author:     Anton Vorontsov <avorontsov at ru.mvista.com>
AuthorDate: Fri Mar 28 22:10:54 2008 +0300
Committer:  David Woodhouse <dwmw2 at infradead.org>
CommitDate: Tue Apr 22 21:13:53 2008 +0100

    [MTD] [NAND] fsl_elbc_nand: workaround for hangs during nand write
    
    Using current driver elbc sometimes hangs during nand write. Reading back
    last byte helps though (thanks to Scott Wood for the idea).
    
    Signed-off-by: Anton Vorontsov <avorontsov at ru.mvista.com>
    Acked-by: Scott Wood <scottwood at freescale.com>
    Signed-off-by: David Woodhouse <dwmw2 at infradead.org>
---
 drivers/mtd/nand/fsl_elbc_nand.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/drivers/mtd/nand/fsl_elbc_nand.c b/drivers/mtd/nand/fsl_elbc_nand.c
index 919c192..4b69aac 100644
--- a/drivers/mtd/nand/fsl_elbc_nand.c
+++ b/drivers/mtd/nand/fsl_elbc_nand.c
@@ -481,7 +481,7 @@ static void fsl_elbc_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
 	struct fsl_elbc_ctrl *ctrl = priv->ctrl;
 	unsigned int bufsize = mtd->writesize + mtd->oobsize;
 
-	if (len < 0) {
+	if (len <= 0) {
 		dev_err(ctrl->dev, "write_buf of %d bytes", len);
 		ctrl->status = 0;
 		return;
@@ -496,6 +496,15 @@ static void fsl_elbc_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
 	}
 
 	memcpy_toio(&ctrl->addr[ctrl->index], buf, len);
+	/*
+	 * This is workaround for the weird elbc hangs during nand write,
+	 * Scott Wood says: "...perhaps difference in how long it takes a
+	 * write to make it through the localbus compared to a write to IMMR
+	 * is causing problems, and sync isn't helping for some reason."
+	 * Reading back the last byte helps though.
+	 */
+	in_8(&ctrl->addr[ctrl->index] + len - 1);
+
 	ctrl->index += len;
 }