The patch titled
mtd-nand: davinci: Correct 4-bit error correction
has been added to the -mm tree. Its filename is
mtd-nand-davinci-correct-4-bit-error-correction.patch
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------------------------------------------------------
Subject: mtd-nand: davinci: Correct 4-bit error correction
From: Sudhakar Rajashekhara <sudhakar.raj@xxxxxx>
On TI's DA830/OMAP-L137, DA850/OMAP-L138 and DM365, after setting the
4BITECC_ADD_CALC_START bit in the NAND Flash control register to 1 and
before waiting for the NAND Flash status register to be equal to 1, 2 or
3, we have to wait till the ECC HW goes to correction state. Without this
wait, ECC correction calculations will not be proper.
This has been tested on DA830/OMAP-L137, DA850/OMAP-L138, DM355 and DM365
EVMs.
Signed-off-by: Sudhakar Rajashekhara <sudhakar.raj@xxxxxx>
Acked-by: Sneha Narnakaje <nsnehaprabha@xxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN drivers/mtd/nand/davinci_nand.c~mtd-nand-davinci-correct-4-bit-error-correction drivers/mtd/nand/davinci_nand.c
--- a/drivers/mtd/nand/davinci_nand.c~mtd-nand-davinci-correct-4-bit-error-correction
+++ a/drivers/mtd/nand/davinci_nand.c
@@ -310,6 +310,7 @@ static int nand_davinci_correct_4bit(str
unsigned short ecc10[8];
unsigned short *ecc16;
u32 syndrome[4];
+ u32 ecc_state;
unsigned num_errors, corrected;
/* All bytes 0xff? It's an erased page; ignore its ECC. */
@@ -360,6 +361,21 @@ compare:
*/
davinci_nand_writel(info, NANDFCR_OFFSET,
davinci_nand_readl(info, NANDFCR_OFFSET) | BIT(13));
+
+ /*
+ * ECC_STATE field reads 0x3 (Error correction complete) immediately
+ * after setting the 4BITECC_ADD_CALC_START bit. So if you immediately
+ * begin trying to poll for the state, you may fall right out of your
+ * loop without any of the correction calculations having taken place.
+ * The recommendation from the hardware team is to wait till ECC_STATE
+ * reads less than 4, which means ECC HW has entered correction state.
+ */
+ do {
+ ecc_state = (davinci_nand_readl(info,
+ NANDFSR_OFFSET) >> 8) & 0x0f;
+ cpu_relax();
+ } while (ecc_state < 4);
+
for (;;) {
u32 fsr = davinci_nand_readl(info, NANDFSR_OFFSET);
_
Patches currently in -mm which might be from sudhakar.raj@xxxxxx are
linux-next.patch
mtd-nand-davinci-correct-4-bit-error-correction.patch
mtdpart-memory-accessor-interface-for-mtd-layer.patch
davinci-mmc-modify-data-types-of-edma-related-variables.patch
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