[U-Boot-Users] u-boot and CONFIG_MTD_NAND_ECC_SMC patch

[mark roths]

Sorry if this has been covered already, the problem exists in all the u-boot
versions I have up to 1.2.0.

When linux has CONFIG_MTD_NAND_ECC_SMC configured, NAND flash sectors
written under linux appear to have ECC errors when read by u-boot.

The help for CONFIG_MTD_NAND_ECC_SMC:
Software ECC according to the Smart Media Specification.
The original Linux implementation had byte 0 and 1 swapped.

u-boot appears to conform to the 'original' linux implementation.  The
following patch fixes this.

*** ../u-boot-1.1.5/drivers/nand/nand_ecc.c     2006-10-20
08:54:33.000000000 -0700
--- drivers/nand/nand_ecc.c     2008-06-10 12:59:21.000000000 -0700
***************
*** 118,123 ****
--- 118,124 ----
 {
       u_char idx, reg1, reg2, reg3;
       int j;
+       u_char tmp0, tmp1;

       /* Initialize variables */
       reg1 = reg2 = reg3 = 0;
***************
*** 140,148 ****
--- 141,157 ----
       /* Create non-inverted ECC code from line parity */
       nand_trans_result(reg2, reg3, ecc_code);

+ #define CONFIG_MTD_NAND_ECC_SMC
       /* Calculate final ECC code */
+ #ifdef CONFIG_MTD_NAND_ECC_SMC
+       tmp0 = ~ecc_code[0];
+       tmp1 = ~ecc_code[1];
+       ecc_code[0] = tmp1;
+       ecc_code[1] = tmp0;
+ #else
       ecc_code[0] = ~ecc_code[0];
       ecc_code[1] = ~ecc_code[1];
+ #endif
       ecc_code[2] = ((~reg1) << 2) | 0x03;
       return 0;
 }


Mark Roths
Softair Microsystems