On Fri, Jul 1, 2011 at 1:42 PM, Scott Wood <scottw...@freescale.com> wrote:
> On Fri, 1 Jul 2011 13:29:41 -0700 > Ran Shalit <ransha...@gmail.com> wrote: > > > I might be missing something... > > When using nand_write_skip_bad, the aligned offset refers to page (not > > sector or block), so if as I understand , I can read from the start of > > page the whole relevant data, then modify only the parts which is > changed, > > That's not the same thing as just filling in the parts you're not writing > with 0xFFs, but still it's not safe unless you erase the block. Even if > the > main portion of the page doesn't contain any bits that go from 0 to 1, and > you've got the data to calculate the proper new ECC, the ECC itself will > probably have bits going from 0 to 1. > > Plus, some chips may not take writing 0xFFs as a no-op -- see the > recent patches to support skipping pages with all 0xFFs on write. > > > and then write it again, but the writing is not for the entire block: I > will > > use the nand_write_skip_bad given offset of the start of page, and > length > > will be the unaligned length for the whole data being written (which is > part > > of the entire block). > > If you're going to keep things page-aligned but just not block-aligned, > you'll be OK as far as ECC and such goes, but you're on your own for making > sure you've accounted for any previous bad blocks that were supposed to be > skipped. > > What is the high-level goal you're trying to accomplish? > > -Scott > > The high-level Goal is writing&reading data which reside in unaligned offset with unaligned data. I hoped that I'll accomplish that by using my own functions which will call the nand_write_skip_bad & nand_read_skip_bad with some sort of read-modify-write method, or (other option I thought of) by adding patch to the nand_write_skip_bad&nand_read_skip_bad functions, so that they will handle unaligned offset&data. As I understand doing the second option right might be more complex. Ran Ran
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