projects / people / ms / u-boot.git / blame
| Commit | Line | Data |
|---|---|---|
| bdfd59aa WJ |
1 | How to enable PMECC(Programmable Multibit ECC) for nand on Atmel SoCs |
| 2 | ----------------------------------------------------------- | |
| 3 | 2012-08-22 Josh Wu <josh.wu@atmel.com> | |
| 4 | ||
| 5 | The Programmable Multibit ECC (PMECC) controller is a programmable binary | |
| 6 | BCH(Bose, Chaudhuri and Hocquenghem) encoder and decoder. This controller | |
| 7 | can be used to support both SLC and MLC NAND Flash devices. It supports to | |
| 8 | generate ECC to correct 2, 4, 8, 12 or 24 bits of error per sector (512 or | |
| 9 | 1024 bytes) of data. | |
| 10 | ||
| 11 | Following Atmel AT91 products support PMECC. | |
| 12 | - AT91SAM9X25, X35, G25, G15, G35 (tested) | |
| 13 | - AT91SAM9N12 (not tested, Should work) | |
| 14 | ||
| 15 | As soon as your nand flash software ECC works, you can enable PMECC. | |
| 16 | ||
| 17 | To use PMECC in this driver, the user needs to set: | |
| 18 | 1. the PMECC correction error bits capability: CONFIG_PMECC_CAP. | |
| 19 | It can be 2, 4, 8, 12 or 24. | |
| 20 | 2. The PMECC sector size: CONFIG_PMECC_SECTOR_SIZE. | |
| 21 | It only can be 512 or 1024. | |
| bdfd59aa WJ |
22 | |
| 23 | Take AT91SAM9X5EK as an example, the board definition file likes: | |
| 24 | ||
| 25 | /* PMECC & PMERRLOC */ | |
| 26 | #define CONFIG_ATMEL_NAND_HWECC 1 | |
| 27 | #define CONFIG_ATMEL_NAND_HW_PMECC 1 | |
| 28 | #define CONFIG_PMECC_CAP 2 | |
| 29 | #define CONFIG_PMECC_SECTOR_SIZE 512 |