On Thu, Nov 22, 2012 at 20:06:41, Philip, Avinash wrote: > On Thu, Nov 22, 2012 at 16:13:52, Artem Bityutskiy wrote: > > On Wed, 2012-11-21 at 07:01 +0000, Philip, Avinash wrote: > > > > I am not sure how this dependency has to be handled for this series, > > > > let me know whether you still want it to be made over l2-mtd? > > > > > > Artem, > > > > > > Is it possible for you to give ack for these patches so that these patches > > > can go in Tony's tree where Omap-gpmc changes are present? > > > > I would prefer if people like Ivan could take a look at this first. > > Ok. Ivan/Artem, Any comments in this patch series? I hope ELM support can get in 3.8. > > > > > Also, I am not sure this is a good idea. Or at least we should agree on > > some common strategy for bit-flips in the erased areas: > > > > "+ * 1. If page is erased, check with standard ecc vector (ecc vector > > + * for erased page to find any bit flip). If check fails, bit flip > > + * is present in erased page. Count the bit flips in erased page and > > + * if it falls under correctable level, report page with 0xFF and > > + * update the correctable bit information." > > > > Idea here is to make faster scanning of erased page without bit flips. > For omap nand driver ecc reported by hardware is non-zero and non 0xff. > So comparing with the standard vector for erased page and skipping error > correction for erased page without bit flips. > > Strategy for bit flips in erased page bit flips, can be > 1. Don't make as erased page and mark it as bad. > 2. Report the erased page with correctable bit flip if it falls under > correctable level. Report the page with erased page with correctable > errors. > Is the concern is here with erased page with correctable error? > I think as error is under correctable level, we still can use the page. > May be we can think of limiting the check to half of correctable level? > > I would go for option 2, see discussion [1]. > > Option 2 adopted in this patch series. > > > Basically, you are working-around JFFS2 limitations. > > > > Do you suggest we do this in all the drivers? > > I am not sure how the situation handled in other drivers. > This depends on the platforms. This method can be adopted for > platforms where ecc reported non-zero & non 0xff with erased page. Any comments? Thanks Avinash > > > > > If we want to do this, may be we better do this in higher level, common > > to all drivers? > > > > I doubt how we handle in higher level with existing MTD setup. > Issues I am seeing on implementing at higher layer is > 1. Calculation of standard ecc vector for erased page. > 2. Skipping ecc error correction, as currently error correction in > .read_page() > Can be handled by adding common .read_page() method on certain flag, > populated for platform specific. > > 1. http://lists.infradead.org/pipermail/linux-mtd/2011-April/034604.html > > Thanks > Avinash > > > -- > > Best Regards, > > Artem Bityutskiy > > > > ��.n��������+%������w��{.n�����{����* jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
