ubi移植与flash替换问题

我在用TI的dm368开发板，kernel是2.6.32.17，默认的flash文件系统是jffs2，但是jffs2在大分区下，mount速度很慢，而且占用ram较多，因此，我想使用ubifs看看性能是否会更好些。

ubifs的原理和配置过程，很多网页都有介绍的，我给一个链接，大家可以看看，我就不转载了，我重点说我移植过程中遇到并解决的问题。

http://bbs.chinaunix.net/thread-1954881-1-1.html

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kerne的配置很简单，2.6.32里面都有，选上并重新编译就好了。

ubiattach、ubimkvol等工具，TI的dvsdk里面自带了，能用，我就偷了个懒，没有重新编译。

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很轻松的照着网页说明操作了下，mount 分区也成功了，复制文件也成功了，很高兴：）

ubiattach /dev/ubi_ctrl -m 3

ubimkvol? /dev/ubi0 -N rootfs -s 480MiB

mount -t ubifs? ubi0_0 /mnt/nand/ -o sync

但很快就遇到麻烦了，开发板关机重新启动，我再mout ubi文件系统就出错了，提示了一堆错误，而且分区是空的，之前复制的文件不见了。

问题如下：

ubiattach /dev/ubi_ctrl -m 3

UBI error: ubi_io_read: error -74while reading 64 bytes from PEB 1662:0,read 64 bytes

UBI error: ubi_io_read: error -74while reading 64 bytes from PEB 1663:0,read 64 bytes

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为了分析问题，我把mtd和ubifs的debug log都打开了，看到了一些信息；

#define?? EBADMSG?????????? 74?? /* Not a data message */

????????????? /*Nand returns -EBADMSG on ecc errors,but it returns

????????????? ?* the data. For our userspace tools it isimportant

????????????? ?* to dump areas with ecc errors !

????????????? ?* For kernel internal usage it also mightreturn -EUCLEAN

????????????? ?* to signal the caller that a bitflip hasoccured and has

????????????? ?* been corrected by the ECC algorithm.

????????????? ?* Userspace software which accesses NAND thisway

????????????? ?* must be aware of the fact that it deals withNAND

????????????? ?*/

nand_do_read_ops

?????? stats= mtd->ecc_stats;

?????? if(mtd->ecc_stats.failed - stats.failed)

????????????? return-EBADMSG;

??

nand_read_page_hwecc

????????????? stat= chip->ecc.correct(mtd,p,&ecc_code[i],&ecc_calc[i]);

????????????? if(stat < 0)

???????????????????? mtd->ecc_stats.failed++;

????????????? else

???????????????????? mtd->ecc_stats.corrected+= stat;

看样子，应该是ECC出错了，可是我用的是硬件ECC校验，怎么可能几乎全部的page都出现ecc校验错误了呢？

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root@dm368-evm:~#flash_eraseall? /dev/mtd3

root@dm368-evm:~# ubiattach/dev/ubi_ctrl -m 3

UBI: attaching mtd3 to ubi0

UBI: physical eraseblock size:?? 131072 bytes (128 KiB)

UBI: logical eraseblock size:??? 129024 bytes

UBI: smallest flash I/O unit:??? 2048

UBI: sub-page size:??????????????512

UBI: VID header offset:????????? 512 (aligned 512)

UBI: data offset:????? ??????????2048

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分析下UBI写数据的过程，

UBI DBG (pid 1484): ubi_io_write:write 512 bytes to PEB 57:0

int ubi_io_write(struct ubi_device*ubi,const void *buf,int pnum,int offset,

????????????? ?int len)

?????? addr= (loff_t)pnum * ubi->peb_size + offset;

?????? err= ubi->mtd->write(ubi->mtd,addr,len,&written,buf);

在io_init函数中可以看到几个变量的赋值；

?????? ubi->peb_size?? = ubi->mtd->erasesize;

?????? ubi->peb_count? = mtd_div_by_eb(ubi->mtd->size,ubi->mtd);

?????? ubi->flash_size= ubi->mtd->size;

从debug log来看，这里一次写了512字节，从某个block的起始page开始，offset是0；

那么到了nand mtd底层驱动，行为就是；

nand_write->nand_do_write_ops:

?????? subpage= column || (writelen & (mtd->writesize - 1));

这里，subpage就是writelen，512；

也可以得知一点，ubifs没有使用oob，这跟jffs2和yaffs2是不同的；

????????????? /*Partial page write ? */

????????????? if(unlikely(column || writelen < (mtd->writesize - 1))) {

???????????????????? cached= 0;

???????????????????? bytes= min_t(int,bytes - column,(int) writelen);

???????????????????? chip->pagebuf= -1;

???????????????????? memset(chip->buffers->databuf,0xff,mtd->writesize);

???????????????????? memcpy(&chip->buffers->databuf[column],buf,bytes);

???????????????????? wbuf= chip->buffers->databuf;

????????????? }

????????????? ret= chip->write_page(mtd,chip,wbuf,page,cached,

??????????????????????????? ?????? (ops->mode == MTD_OOB_RAW));

下面是write_page函数的代码；

static int nand_write_page(structmtd_info *mtd,struct nand_chip *chip,

???????????????????? ?? const uint8_t *buf,int page,int cached,int raw)

{

?????? intstatus;

?

?????? chip->cmdfunc(mtd,NAND_CMD_SEQIN,0x00,page);

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?????? if(unlikely(raw))

????????????? chip->ecc.write_page_raw(mtd,buf);

?????? else

????????????? chip->ecc.write_page(mtd,buf);

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?????? /*

?????? ?* Cached progamming disabled for now,Not sureif its worth the

?????? ?* trouble. The speed gain is not veryimpressive. (2.3->2.6Mib/s)

?????? ?*/

?????? cached= 0;

这里需要注意的就是raw，如果是MTD_OOB_RAW，那么不会做ECC校验，也不会把ECC码写入OOB；

如果是这样，在read的时候也必须指定是MTD_OOB_RAW，不需要ECC校验；否则，就会出现我们最开始看到的错误；

?????? if(mtd->ecc_stats.failed - stats.failed)

????????????? return-EBADMSG;

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那么，从这里的情况来看，我们可能已经找到出错的原因了；ubi使用了subpage write，而底层nand flash驱动实际上是不支持subpage write的，尽管ubi一次只写了512字节，但这个page的其他部分已经不能再次写入新的数据了。

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从Nand_base.c(driversmtdnand)来看，large page的nand flash，对subpage write的支持是不完善的，限制条件比较多，比如，不能是MLC的nand flash，不能用硬件ECC；

更严重的问题是代码存在缺陷，在写入部分data的时候，将其他部分的数据填充为0xff了，然后write整个page，并写入全部ecc码到oob，也许这就是前面ecc校验出错的原因吧。

nand_do_write_ops()

????????????? /*Partial page write ? */

memset(chip->buffers->databuf,bytes);

因此，我想到的解决办法就是在nand驱动中禁止subpage write。

第一步，在chip options中增加NAND_NO_SUBPAGE_WRITE；

static struct davinci_nand_pdatadavinci_nand_data = {

?????? .options???????? = NAND_USE_FLASH_BBT|NAND_NO_SUBPAGE_WRITE,

然后重新编译下载kernel，但问题依旧；

root@dm368-evm:~# ubiattach/dev/ubi_ctrl -m 3

UBI: attaching mtd3 to ubi0

UBI: physical eraseblock size:?? 131072 bytes (128 KiB)

UBI: logical eraseblock size:??? 129024 bytes

UBI: smallest flash I/O unit:??? 2048

UBI: sub-page size:????????????? 512

UBI: VID header offset:????????? 512 (aligned 512)

心想很奇怪，为什么?sub-page size还是512？

回头查看代码，想看看sub page size是怎样计算出来的，

?if (!(chip->options & NAND_NO_SUBPAGE_WRITE) &&
???? !(chip->cellinfo & NAND_CI_CELLTYPE_MSK)) {
??switch(chip->ecc.steps) {
??case 2:
???mtd->subpage_sft = 1;
???break;
??case 4:
??case 8:
??case 16:
???mtd->subpage_sft = 2;
???break;
??}
?}
?chip->subpagesize = mtd->writesize >> mtd->subpage_sft;

可是我已经给options增加了NAND_NO_SUBPAGE_WRITE啊？有些怀疑，我就在此处加了打印log，果然是这里出了问题，

chip->options = 0x10101.

mtd->subpage_sft = 0.

chip->subpagesize = 512.

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#define NAND_NO_SUBPAGE_WRITE??? 0x00000200

可是，这里的options 明明是不对的！那我设置的NAND_NO_SUBPAGE_WRITE在哪里丢掉了？

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在下面的函数中有对chip->options赋值改变；

nand_get_flash_type()

?????? ?????? printk(KERN_INFO"nand_get_flash_type 1,chip->options = 0x%x.n",chip->options);

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?????? /*Get chip options,preserve non chip based options */

???????chip->options &= ~NAND_CHIPOPTIONS_MSK;

?????? printk(KERN_INFO"nand_get_flash_type 2,chip->options); ??

?????? chip->options|= type->options & NAND_CHIPOPTIONS_MSK;

?????? printk(KERN_INFO"nand_get_flash_type 3,chip->options);

?

?????? /*

?????? ?* Set chip as a default. Board drivers canoverride it,if necessary

?????? ?*/

?????? chip->options|= NAND_NO_AUTOINCR;

?

?????? /*Check if chip is a not a samsung device. Do not clear the

?????? ?* options for chips which are not having anextended id.

?????? ?*/

?????? if(*maf_id != NAND_MFR_SAMSUNG && !type->pagesize)

????????????? chip->options&= ~NAND_SAMSUNG_LP_OPTIONS;

?????? printk(KERN_INFO"nand_get_flash_type 4,chip->options);

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nand_get_flash_type 1,chip->options = 0x10200.

nand_get_flash_type 2,chip->options = 0x10000.

nand_get_flash_type 3,chip->options = 0x1011c.

nand_get_flash_type 4,chip->options = 0x10101.

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问题出在这里，红色的代码！

/* Mask to zero out thechip options,which come from the id table */

#defineNAND_CHIPOPTIONS_MSK?(0x0000ffff &~NAND_NO_AUTOINCR)

/* Chip can not autoincrement pages */

#define NAND_NO_AUTOINCR??0x00000001

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找到问题了，解决办法就有了，注释掉红色的那行代码，就是他把NAND_NO_SUBPAGE_WRITE给丢掉了。

//chip->options &=~NAND_CHIPOPTIONS_MSK;

再重新编译下载kernel，问题搞定了！

再次启动开发板，加载ubi，一切正常了。

root@dm368-evm:/# ubiattach/dev/ubi_ctrl -m 3

UBI: attaching mtd3 to ubi0

UBI: physical eraseblock size:?? 131072 bytes (128 KiB)

UBI: logical eraseblock size:??? 126976 bytes

UBI: smallest flash I/O unit:??? 2048

UBI: VID header offset:????????? 2048 (aligned 2048)

UBI: data offset:??????????????? 4096

UBI: attached mtd3 to ubi0

UBI: MTD device name:??????????? "filesystem1"

UBI: MTD device size:??????????? 512 MiB

UBI: number of good PEBs:??????? 4096

UBI: number of bad PEBs:???????? 0

UBI: max. allowed volumes:?????? 128

UBI: wear-leveling threshold:??? 4096

UBI: number of internal volumes: 1

UBI: number of user volumes:???? 1

UBI: available PEBs:???????????? 3639

UBI: total number of reserved PEBs:457

UBI: number of PEBs reserved for badPEB handling: 40

UBI: max/mean erase counter: 2/1

UBI: image sequence number: 0

UBI: background thread"ubi_bgt0d" started,PID 1483

UBI device number 0,total 4096 LEBs(520093696 bytes,496.0 MiB),available 3639 LEBs (462065664 bytes,440.7 MiB),LEB size 126976 bytes (124.0 KiB)

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root@dm368-evm:/# mount -tubifs? ubi0_0 /mnt/nand/ -o sync

UBIFS: mounted UBI device 0,volume0,name "rootfs"

UBIFS: file system size:?? 51171328 bytes (49972 KiB,48 MiB,403 LEBs)

UBIFS: journal size:?????? 2539520 bytes (2480 KiB,2 MiB,20 LEBs)

UBIFS: media format:?????? w4/r0 (latest is w4/r0)

UBIFS: default compressor: lzo

UBIFS: reserved for root:? 2416947 bytes (2360 KiB)

root@dm368-evm:/# df

Filesystem?????????? 1K-blocks????? Used Available Use% Mounted on

/dev/root???????????? 39544232? 16239820?21295632? 43% /

none????????????????????? 1024??????? 24?????1000?? 2% /dev

tmpfs??????????????????? 16384??????? 20????16364?? 0% /var/volatile

tmpfs??????????????????? 21760???????? 0????21760?? 0% /dev/shm

tmpfs??????????????????? 16384???????? 0????16384?? 0% /media/ram

ubi0_0?????????????????? 45528????? 1528????41640?? 4% /mnt/nand

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最后，总结下，就是要禁止nand flash驱动里面的subpage write，让?chip->subpagesize == mtd->writesize 就好了。

这是我的解决办法。如果有人要使用subpage write，那么一定要保证你的读写逻辑是正确的，要么不用ecc，要么各个subpage的ecc都应是正确的。

http://www.61ic.com/Article/DaVinci/TMS320DM3x/201307/49496.html