> -----Original Message----- > From: Grazvydas Ignotas [mailto:notasas@xxxxxxxxx] > Sent: Friday, November 19, 2010 4:06 PM > To: Ghorai, Sukumar > Cc: Charles Manning; linux-omap@xxxxxxxxxxxxxxx > Subject: Re: No more software ECC in omap2.c NAND driver. Why? > > On Thu, Nov 18, 2010 at 4:33 PM, Ghorai, Sukumar <s-ghorai@xxxxxx> wrote: > >> -----Original Message----- > >> From: linux-omap-owner@xxxxxxxxxxxxxxx [mailto:linux-omap- > >> owner@xxxxxxxxxxxxxxx] On Behalf Of Charles Manning > >> Sent: Thursday, November 18, 2010 6:36 AM > >> To: linux-omap@xxxxxxxxxxxxxxx > >> Subject: No more software ECC in omap2.c NAND driver. Why? > >> > >> Between 2.6.35 and 2.6.36 there have need quite a few changes in the > NAND > >> driver, including a change from software to hardware ECC. > >> > >> The new code has hardware ECC forced on by: > >> > >> #define CONFIG_MTD_NAND_OMAP_HWECC > >> > >> I am surprised that this was done. Surely this should have been a > Kconfig > >> option to select either sw ECC or hw ECC? > >> > >> Does moving to hardware ECC to the exclusion of software ECC reduce > >> functionality? > > > > [Ghorai] This is wrongly added by me, during last few patches. So I have > > send the fix as you mentioned too as. > > [PATCH] omap: nand: remove hardware ECC as default > > > > And please let me know still if it has any issue. > > For me it makes normal sw ECC page IO work, but for subpages to work I > have to disable the prefetch option. [Ghorai] I was thinking that I have modularize some GPMC call and did not do anything prefetch related modificaiton. I will check this too. > > > And I am re-working on the patches for the different ecc schema > including > > s/w, h/w or different, to pass it form board file. > > > >> > >> Does the new hwecc scheme still support sub-page writes or does it only > >> provide full page writes? If sub-page writes are lost then this has a > >> ripple > >> effect in breaking the way some UBI stuff works. > > > > [Ghorai] > > 1. do you think this sub-page read/write support was there before, say > in > > 2.6.35? And breaks in 2.6.36? > > It certainly was there for sw ECC as we've been using UBI from 2.6.27 > to 2.6.35 just fine. [Ghorai] uoderstand. > > > 2. In that case would you please let know what are the size(s) used for > > sub-page/read write? > > 512 bytes. [Ghorai] I feel still its support in 2.6.36 too. Let me check too. -- 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
