Hi Gražvydas, On 08/05/2014 07:15 PM, Grazvydas Ignotas wrote: > On Tue, Aug 5, 2014 at 1:11 PM, Roger Quadros <rogerq@xxxxxx> wrote: >> For v3.12 and prior, 1-bit Hamming code ECC via software was the >> default choice. Commit c66d039197e4 in v3.13 changed the behaviour >> to use 1-bit Hamming code via Hardware using a different ECC layout >> i.e. (ROM code layout) than what is used by software ECC. >> >> This ECC layout change causes NAND filesystems created in v3.12 >> and prior to be unusable in v3.13 and later. So revert back to >> using software ECC by default if an ECC scheme is not explicitely >> specified. >> >> This defect can be observed on the following boards during legacy boot >> >> -omap3beagle >> -omap3touchbook >> -overo >> -am3517crane >> -devkit8000 >> -ldp >> -3430sdp > > omap3pandora is also using sw ecc, with ubifs. Some time ago I tried > booting mainline (I think it was 3.14) with rootfs on NAND, and while > it did boot and reached a shell, there were lots of ubifs errors, fs > got corrupted and I lost all my data. I used to be able to boot > mainline this way fine sometime ~3.8 release. It's interesting that > 3.14 was able to read the data, even with wrong ecc setup. This is due to another bug introduced in 3.7 by commit 65b97cf6b8deca3ad7a3e00e8316bb89617190fb. Because of that bug (i.e. inverted CS_MASK in omap_calculate_ecc), omap_calculate_ecc() always fails with -EINVAL and calculated ECC bytes are always 0. I'll be sending a patch to fix that as well. But that will only affect the cases where OMAP_ECC_HAM1_CODE_HW is used which happened for pandora from 3.13 onwards. > > Do you think it's safe again to boot ubifs created on 3.2 after > applying this series? > Yes. If you boot pandora using legacy boot (non DT method), it passes 0 for .ecc_opt in pandora_nand_data. This used to mean OMAP_ECC_HAMMING_CODE_DEFAULT which is software ecc. i.e. NAND_ECC_SOFT with default ECC layout. Until the above mentioned commits changed the meaning. We now call that option OMAP_ECC_HAM1_CODE_SW. Please let me know if it works for you. Thanks. cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
