Sandeep and all interested parties: I am trying to understand davinci 4-bit nand options for u-boot and linux. I did some searching and found this comment in the davinci nand driver for openocd:
/* * "Infix" OOB ... like Linux ECC_HW_SYNDROME. Avoided because it trashes * manufacturer bad block markers, except on small page chips. Once you * write to a page using this scheme, you need specialized code to update * it (code which ignores now-invalid bad block markers). * * This is needed *only* to support older firmware. Older ROM Boot Loaders * need it to read their second stage loader (UBL) into SRAM, but from then * on the whole system can use the cleaner non-infix layouts. Systems with * older second stage loaders (ABL/U-Boot, etc) or other system software * (MVL 4.x/5.x kernels, filesystems, etc) may need it more generally. */ This appears to be the ecc mode that Sandeep is trying to establish as the norm going forward. It seems that David (author of the openocd code) would make a different choice. So what is the "right" thing to do? We are starting development of a new board and need to make a decision. What are the pros and cons of the two 4-bit alternatives? Here is my two cents (maybe three cents) from my own experience: On the one hand, you can mitigate the trashed bad block marker problem by using an in flash bad block table that you create on first boot. Theoretically you never need the manufactuer markers after that. On the other hand, I know that Control4 (where I work now) had difficulty getting nand chips pre-programmed for an i.MX31 platform that had interleaved ecc like this. I believe the workaround involved post processing an image to "fool" the nand programmer that assumed a conventional oob layout. At Freescale I worked on a nand driver for the MPC5121 that had similar issues and it was disliked so much that the driver that finally made it into u-boot has software ecc only. Thanks for any input from all informed parties. John _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
