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mtd/nand/fsl_elbc_nand: workaround for hangs on MPC837X

PATCH In review Anton Vorontsov 2 participants 4 messages Mar 28, 2008

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Anton Vorontsov

author
#0 lore raw

PATCH 1/1 mtd/nand/fsl_elbc_nand: workaround for hangs on MPC837X

Using current driver on the MPC837X CPUs elbc hangs during nand write. Reading last byte helps though (thanks to Scott Wood for the idea).

Signed-off-by Anton Vorontsov <[email protected]>
---
 drivers/mtd/nand/fsl_elbc_nand.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)
drivers/mtd/nand/fsl_elbc_nand.c +11 -1
index 378b7aa..be4c05d 100644
@@ -480,7 +480,7 @@ 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;

@@ -495,6 +495,16 @@ static void fsl_elbc_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
 	}
 
 	memcpy_toio(&ctrl->addr[ctrl->index], buf, len);
+#ifdef CONFIG_PPC_MPC837x
+	/*
+	 * This is workaround for the weird elbc hangs on the MPC837X CPUs,
+	 * 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);
+#endif
 	ctrl->index += len;
 }
Signature · 1 line
1.5.2.2
#1 lore raw
Quoted 4 lines · Anton Vorontsov
drivers/mtd/nand/fsl_elbc_nand.c +0 -0
@@ -495,6 +495,16 @@ static void fsl_elbc_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
 	}
 
 	memcpy_toio(&ctrl->addr[ctrl->index], buf, len);

drivers/mtd/nand/fsl_elbc_nand.c static void fsl_elbc_write_buf(struct mtd_info *mtd, const u8 *buf, int len) · line 507

Quoted 10 lines
drivers/mtd/nand/fsl_elbc_nand.c +10 -0
+#ifdef CONFIG_PPC_MPC837x
+	/*
+	 * This is workaround for the weird elbc hangs on the MPC837X CPUs,
+	 * 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);
+#endif

Let's do it regardless of chip -- odds are the issue exists on all implementations, and it's just a function of what frequencies things are running at.

-Scott

author
#2 lore raw

PATCH 1/1 mtd/nand/fsl_elbc_nand: workaround for hangs during nand write [was: Re: [PATCH] mtd/nand/fsl_elbc_nand: workaround for hangs on MPC837X]

Quoted 5 lines · Scott Wood
Quoted 4 lines · Anton Vorontsov
(quoted diff) +0 -0
@@ -495,6 +495,16 @@ static void fsl_elbc_write_buf(struct mtd_info *mtd, 
 const u8 *buf, int len)
 	}
Quoted 15 lines

Review static void fsl_elbc_write_buf(struct mtd_info *mtd, · line 508

Quoted 11 lines
(quoted diff) +10 -0
 	memcpy_toio(&ctrl->addr[ctrl->index], buf, len);
+#ifdef CONFIG_PPC_MPC837x
+	/*
+	 * This is workaround for the weird elbc hangs on the MPC837X CPUs,
+	 * 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);
+#endif

Let's do it regardless of chip -- odds are the issue exists on all implementations, and it's just a function of what frequencies things are running at.

Ok.

- - - -
From: Anton Vorontsov <[email protected]>
Subject: 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 <[email protected]>
---
 drivers/mtd/nand/fsl_elbc_nand.c |   11 ++++++++++-
 1 files changed, 10 insertions(+), 1 deletions(-)
drivers/mtd/nand/fsl_elbc_nand.c +10 -1
index 378b7aa..2f4ce2a 100644
@@ -480,7 +480,7 @@ 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;

@@ -495,6 +495,15 @@ 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;
 }
Signature · 1 line
1.5.2.2
Acked-by on v1 1/1
#3 lore raw

Re: [PATCH] mtd/nand/fsl_elbc_nand: workaround for hangs during nand write [was: Re: [PATCH] mtd/nand/fsl_elbc_nand: workaround for hangs on MPC837X]

Quoted 7 lines · Anton Vorontsov

From: Anton Vorontsov <[email protected]>
Subject: 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 <[email protected]>
Acked-by Scott Wood <[email protected]>

-Scott