On Mon, Dec 01, 2014 at 09:18:18PM +0100, Boris Brezillon wrote: > On Mon, 1 Dec 2014 11:41:39 -0800 Brian Norris <computersforpe...@gmail.com> > wrote: > > On Mon, Dec 01, 2014 at 08:12:39PM +0100, Boris Brezillon wrote: > > > Brian, I really like the idea of having a generic implementation for this > > > feature (using read_page_raw) as you suggested here [1], but this implies > > > having a temporary buffer to store the page read in raw mode and keep the > > > page > > > read in normal (HW ECC engine eanbled) mode, and I'm not sure we want to > > > allocate more buffers than we already have. > > > > Why does this require an additional buffer? If we've already noticed an > > ECC error, we're expected to return raw data anyway, so what's the > > problem with clobbering the original data with a raw version of the > > data? > > Well in the GPMI particular case (and more generally all NAND > controllers which do not support subpage write) this is true, but if you > can do subpage write, then you might have a bit flip in a specific > chunk which is still empty, while other chunks are written and are > expecting standard ECC correction. > In this case you want to keep the 3 chunks with standard ECC correction > and only one in raw mode with 'erased page bitflips' fixed.
So the problem's not really with subpage write, exactly; the problem is for drivers that support subpage write, we don't have a way to perform a raw subpage read without touching the other subpages. Brian -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
