[PATCH] mxc_nand: i.MX35 hardware ECC fixups

[PATCH] mxc_nand: i.MX35 hardware ECC fixups

[John Ogness]

This patch is against the recently posted patches from Sascha Hauer
(21 Oct 2009 mxc_nand). This patch does the following:

 - fixes ECC hardware error detection for the i.MX35
 - sets up an appropriate ECC mode (4-bit) for the i.MX35
 - configures the spare area size for the i.MX35

I tested this patch with ubifs on an i.MX35 PDK board.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 mxc_nand.c |   35 ++++++++++++++++++++++++++++++-----
 1 file changed, 30 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
index d5445cd..de056aa 100644
--- a/drivers/mtd/nand/mxc_nand.c
+++ b/drivers/mtd/nand/mxc_nand.c
@@ -86,6 +86,7 @@
  * Status operation */
 #define NFC_INT            0x8000
 
+#define NFC_ECC_4BIT        (1 << 0)
 #define NFC_SP_EN           (1 << 2)
 #define NFC_ECC_EN          (1 << 3)
 #define NFC_INT_MSK         (1 << 4)
@@ -351,11 +352,25 @@ static int mxc_nand_correct_data(struct mtd_info *mtd, u_char *dat,
 	 */
 	uint16_t ecc_status = readw(host->regs + NFC_ECC_STATUS_RESULT);
 
-	if (((ecc_status & 0x3) == 2) || ((ecc_status >> 2) == 2)) {
-		DEBUG(MTD_DEBUG_LEVEL0,
-		      "MXC_NAND: HWECC uncorrectable 2-bit ECC error\n");
-		return -1;
-	}
+	if (nfc_is_v21()) {
+		if ((ecc_status & 0xf) > 1 ||
+		    ((ecc_status >> 4) & 0xf) > 1 ||
+		    ((ecc_status >> 8) & 0xf) > 1 ||
+		    ((ecc_status >> 12) & 0xf) > 1) {
+			DEBUG(MTD_DEBUG_LEVEL0,
+			      "MXC_NAND: "
+			      "HWECC uncorrectable 2-bit ECC error\n");
+			return -1;
+		}
+	} else if (nfc_is_v1()) {
+		if (((ecc_status & 0x3) == 2) || ((ecc_status >> 2) == 2)) {
+			DEBUG(MTD_DEBUG_LEVEL0,
+			      "MXC_NAND: "
+			      "HWECC uncorrectable 2-bit ECC error\n");
+			return -1;
+		}
+	} else
+		BUG();
 
 	return 0;
 }
@@ -756,6 +771,8 @@ static int __init mxcnd_probe(struct platform_device *pdev)
 	tmp = readw(host->regs + NFC_CONFIG1);
 	tmp |= NFC_INT_MSK;
 	tmp &= ~NFC_SP_EN;
+	if (nfc_is_v21())
+		tmp |= NFC_ECC_4BIT;
 	writew(tmp, host->regs + NFC_CONFIG1);
 
 	init_waitqueue_head(&host->irq_waitq);
@@ -773,6 +790,14 @@ static int __init mxcnd_probe(struct platform_device *pdev)
 	/* Unlock the internal RAM Buffer */
 	writew(0x2, host->regs + NFC_CONFIG);
 
+	if (nfc_is_v21()) {
+		/* configure spare size (in 16-bit blocks) */
+		tmp = readw(host->regs + NFC_RSLTSPARE_AREA);
+		tmp &= ~0xff;
+		tmp |= host->spare_len / 2;
+		writew(tmp, host->regs + NFC_RSLTSPARE_AREA);
+	}
+
 	/* Blocks to be unlocked */
 	if (nfc_is_v21()) {
 		writew(0x0, host->regs + NFC_V21_UNLOCKSTART_BLKADDR);

Re: [PATCH] mxc_nand: i.MX35 hardware ECC fixups

[alfred steele]

Hi John/Stephanie,
> The patch sets a few registers that Sascha's patches forgot. It also
> correctly notices if there were ECC errors. Without the patch, most ECC
> errors will go unnoticed.
I am having a issue with using nandwrite mtd util and it so happens
that the nandwrite gets stuck at a particular block and the sonsole
hangs there forever.
We are using the mx27(mxc) with a large size page NAND(4k). The annd
write suceeds for the kernel MTD parition. I am suspecting my NAND
driver is somehow obsolete. How do i find out as to what could be the
root cause of the problem?
What could be the pest debugging path?

Cheers,
Alfred.

Re: [PATCH] mxc_nand: i.MX35 hardware ECC fixups

[Eric Bénard]

Hi Alfred,

alfred steele a écrit :
> I am having a issue with using nandwrite mtd util and it so happens
> that the nandwrite gets stuck at a particular block and the sonsole
> hangs there forever.
> We are using the mx27(mxc) with a large size page NAND(4k). The annd
> write suceeds for the kernel MTD parition. I am suspecting my NAND
> driver is somehow obsolete. How do i find out as to what could be the
> root cause of the problem?
are you sure the i.MX27's NAND controler supports 4k NAND ?

 From the Reference Manual is only support 512 & 2k :
The NFC interfaces standard NAND Flash devices to the IC and hides the 
complexities of accessing the NAND Flash. It provides a glueless 
interface to both 8-bit and 16-bit NAND Flash parts with page sizes
of 512 bytes or 2 Kbytes, and densities up to 64 Gbits per 2-Kbyte page 
size NAND Flash, and 8 Gbits per 512 byte page size NAND Flash.

There is no mention of 4k NAND and the NFC's RAM buffer is only 2k + 64 
which may be not enough for 4k NAND (the v2 NFC has 4k + 512 and support 
4k).

Eric

Re: [PATCH] mxc_nand: i.MX35 hardware ECC fixups

[John Ogness]

Hi Alfred,

On 2009-12-13, alfred steele <alfred.jaquez@gmail.com> wrote:
> I am having a issue with using nandwrite mtd util and it so happens
> that the nandwrite gets stuck at a particular block and the sonsole
> hangs there forever.
>
> We are using the mx27(mxc) with a large size page NAND(4k). The annd
> write suceeds for the kernel MTD parition. I am suspecting my NAND
> driver is somehow obsolete. How do i find out as to what could be the
> root cause of the problem?
>
> What could be the pest debugging path?

You may want to consider setting the kernel option MTD_DEBUG and setting
MTD_DEBUG_VERBOSE to 3 (noisy). It will generate a _lot_ of output on
the console, but may help you to identify where it is hanging.

John Ogness