nand

1.當往NAND FLASH 的PAGE中寫入數據時，每寫入512字節產生3字節ECC。並寫入到OOB得ECC位置，此ECC叫做原始ECC。

2.當從NAND FLASH讀數據時，每讀取512字節產生3字節ECC，叫做新ECC。

3.原始ECC異或新ECC

=12 表示有1位錯誤，可以糾正；

=1 表示有表示OOB錯誤

=其他表示無法糾正的錯誤

4.ECC[2]；

32位ECC值=(ECC[2]&0XF0<<20)|ECC[1]<<16 |(ECC[2]&0X0F<<8)|ECC[0]

5.計算ECC值

6.調試結果

7.ECC.MODE=NAND_ECC_HW

8.OOBINFO.ECCBYTES=12;

9.OOBINFO.OOBFREE->OFFSET=1;

10.OOBINFO.OOBFREE->LENGTH=51

11.更改後可以互相寫FLASH，但出現ECC效驗。

12.nandwrite –m /dev/mtd5 uImgae 成功啓動；

對比UBOOT和KERNELECC配置

	u-boot	kernel
Ecc_size_config	Eccsize1+eccsize0+eccsize0sel	Eccsize1+0xf
Ecc_config	dev_width << 7) | (cs << 1) |  (0x1	dev_width << 7) | (cs << 1) |  (0x1
Ecc_control	0x101	0x101
Oob.oobfree.offset	13	1
Oob.oobfree.length	51	51

針對上面問題的修改：

gpmc_write_reg(GPMC_ECC_CONTROL,0x00000101);

//ecc_size_conf_val = (eccsize1<< 22) | 0x0000000F;

ecc_size_conf_val = (eccsize1<< 22) | (eccsize0 << 12)|0x0f;

ecc_conf_val = (dev_width<< 7) | (cs << 1) | (0x1);

ecc_size_conf_val = (eccsize1 << 22)| (eccsize0 << 12)|0x0f;

沒有0X0F就不會進入控制檯，加了會進去，會面研究；

修改：

case GPMC_ECC_WRITE:

if (ecc_type== OMAP_ECC_BCH4_CODE_HW) {

eccsize1 = 0x20; eccsize0 = 0x00;

bch_mod = 0;

bch_wrapmode = 0x06;

} else if(ecc_type == OMAP_ECC_BCH8_CODE_HW) {

eccsize1 = 0x20; eccsize0 = 0x00;

bch_mod = 1;

bch_wrapmode = 0x06;

} else

{

eccsize1= ((ecc_size >> 1) - 1) ;

//add

eccsize0 = ((ecc_size >> 1) - 1) ;

}

break;

製作文件系統問題：

./mkfs.jffs2 -lqnp -e 128 -r sufs -o sufs.jffs2

取消p屬性。

./mkfs.jffs2 -lqn -e 128 -r sufs -o sufs.jffs2

[9.548004]jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0149b358: 0x0200instead

[9.557434]jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0149b36c: 0x4004 instead

[9.566802]jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0149b380: 0x0020instead

[9.576171]jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0149b3a8: 0x0080 instead

[9.585540]jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0149b468: 0x0010instead

[9.594909]jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0149b470: 0x0010instead

[9.604248]jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0149b47c: 0x0004 instead

[9.613616]jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0149b504: 0x0400instead

[9.622985]jffs2_scan_eraseblock(): Magic bitmask 0x1985 not found at 0x0149b570: 0x1000instead

[9.632354] jffs2_scan_eraseblock(): Magicbitmask 0x1985 not found at 0x0149b580: 0x0040 instead

[9.641693] Further suchevents for this erase block will not be printed

[9.652618] Empty flash at0x0149c000 ends at 0x0149c0a8

處理：

./mkfs.jffs2 -lqn -e 128KiB -r sufs -o sufs.jffs2

FLASH空處理

註釋掉打印信息： fs/jffs2/scan.c

inbuf_ofs = ofs - buf_ofs;

while(inbuf_ofs < scan_end) {

if (unlikely(*(uint32_t *)(&buf[inbuf_ofs]) != 0xffffffff)) {

//printk(KERN_WARNING"Empty flash at 0x%08x ends at 0x%08x\n",

//empty_start, ofs);

if((err = jffs2_scan_dirty_space(c, jeb, ofs-empty_start)))

return err;

gotoscan_more;

}

root@am3517-evm:~# cat /proc/mtd

dev:sizeerasesizename

mtd0: 00080000 00020000 "xloader-nand"

mtd1: 001c000000020000 "uboot-nand"

mtd2: 00040000 00020000 "params-nand"

mtd3: 00640000 00020000 "linux-nand"

mtd4: 03e80000 00020000 "jffs2-nand"

mtd5: 00640000 00020000 "linux.bak-nand"

mtd6: 03e80000 00020000 "jffs2.bak-nand"

mtd7: 37400000 00020000 "share-data"