Re: [EXT] Re: [RESEND PATCH V2 2/2] mtd: core: NAND filling block

Miquel Raynal
2019-01-24T20:07:06Z

Hi Bean,

"Bean Huo (beanhuo)" <beanhuo@micron.com> wrote on Thu, 24 Jan 2019
15:47:25 +0000:

> Hi, Miquel
>
> >
> >> On some legacy planar 2D Micron NAND devices when a block erase
> >> command is issued, occasionally even though a block erase operation
> >> successfully completes and returns a pass status, the flash block may
> >> not be completely erased. Subsequent operations to this block on very
> >> rare cases can result in subtle failures or corruption. These
> >> extremely rare cases should nevertheless be considered.
> >>
> >> These rare occurrences have been observed on partially written blocks.
> >> Partially written blocks are not uncommon with UBI/UBIFS.
> >>
> >> To avoid this rare occurrence, we make sure that at least
> >> 15 pages have been programmed to a block before it is erased.
> >> In case we find that less than 15 pages have been programmed,
> >> additional pages are programmed in the block. The observation is that
> >> additional pages rarely need to be written
> >
> >I would stop the commit message here and remove the end of the sentence
> >which, I believe, is inaccurate.
> >
> I don't understand where is inaccurate.
>
> >> and most of
> >> the time UBI/UBIFS erases blocks that contain more programmed pages.

Because UBI/UBIFS is *one* user of MTD. This patch has nothing to do
with UBI/UBIFS. Plus, the sentence is not very clear to me anyway.

Thanks,
Miquèl