[Yaffs] some bit changed from '1' to '0' in one page

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Author: Jia Guo
To: yaffs, duweiA, handong
Subject: [Yaffs] some bit changed from '1' to '0' in one page

I'm doing a serial of test on our target board, under linux and using yaffs2 as rootfs. The test includes memory read/write, ethernet packet send/receive and some yaffs2 filesystem read and write. Our firmware image is stored as a file under yaffs2. After doing the recursive test for about 10 hours under 50C temperature, serveral bytes in firmware image has changed, such as: change from BF 2C to B7 24, or from E4 8D E5 12 to E0 89 E1 10 and so on, all the changes happened at one of the bits from bits[0-3] in a byte, changed from '1' to '0'. The changed bytes are all in one nand page, and I've made sure that the ECC bytes of that page are changed too, and the ECC is generated by hareware. As far as I know, both GC/Wear Leveling and Log recording can cause yaffs2 write. Are there some related issue filed before? Or is it looks like a hardware related issue such as signal integrity?

Thanks Jia