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| author | Sudhakar Rajashekhara <sudhakar.raj@ti.com> | 2010-07-20 15:24:01 -0700 |
|---|---|---|
| committer | David Woodhouse <David.Woodhouse@intel.com> | 2010-08-02 09:09:15 +0100 |
| commit | 1c3275b656045aff9a75bb2c9f3251af1043ebb3 (patch) | |
| tree | ec7a9bae3b851c17c7637c8034edbbec804a44c4 /drivers/mtd/nand/davinci_nand.c | |
| parent | 58373ff0afff4cc8ac40608872995f4d87eb72ec (diff) | |
| download | lwn-1c3275b656045aff9a75bb2c9f3251af1043ebb3.tar.gz lwn-1c3275b656045aff9a75bb2c9f3251af1043ebb3.zip | |
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.c | 17 |
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); |