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authorSudhakar Rajashekhara <sudhakar.raj@ti.com>2010-07-20 15:24:01 -0700
committerDavid Woodhouse <David.Woodhouse@intel.com>2010-08-02 09:09:15 +0100
commit1c3275b656045aff9a75bb2c9f3251af1043ebb3 (patch)
treeec7a9bae3b851c17c7637c8034edbbec804a44c4 /drivers/mtd/nand/davinci_nand.c
parent58373ff0afff4cc8ac40608872995f4d87eb72ec (diff)
downloadblackbird-op-linux-1c3275b656045aff9a75bb2c9f3251af1043ebb3.tar.gz
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mtd: nand: davinci: correct 4-bit error correction
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@ti.com> Acked-by: Sneha Narnakaje <nsnehaprabha@ti.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Diffstat (limited to 'drivers/mtd/nand/davinci_nand.c')
-rw-r--r--drivers/mtd/nand/davinci_nand.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
index 9c9d893affeb..2ac7367afe77 100644
--- a/drivers/mtd/nand/davinci_nand.c
+++ b/drivers/mtd/nand/davinci_nand.c
@@ -311,7 +311,9 @@ static int nand_davinci_correct_4bit(struct mtd_info *mtd,
unsigned short ecc10[8];
unsigned short *ecc16;
u32 syndrome[4];
+ u32 ecc_state;
unsigned num_errors, corrected;
+ unsigned long timeo = jiffies + msecs_to_jiffies(100);
/* All bytes 0xff? It's an erased page; ignore its ECC. */
for (i = 0; i < 10; i++) {
@@ -361,6 +363,21 @@ 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) && time_before(jiffies, timeo));
+
for (;;) {
u32 fsr = davinci_nand_readl(info, NANDFSR_OFFSET);
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