On Fri, Jun 17, 2011 at 5:34 PM, Scott Wood <scottw...@freescale.com> wrote: > > It seems that the generic code always passes -1 with PAGEPROG, and only > provides the actual page address on SEQIN. > > I don't think the ECC readback is needed, and the fact that it looks like > it has always been broken would seem to confirm that. It's broken in > other ways, too -- it assumes a particular ECC layout. Let's get rid of it. > > As for the corruption, could it be degradation from repeated reads of that > one page? >
I modified nanddump to do repeated reads, and compare the data obtained from the first iteration with that obtained later (to detect bit-flips). I tried 3 different variations: - one which reads the first page (2k) of the last block - one which reads the second page (2k) of the last block - one which reads the entire last block (128k), just for comparison As I understand it, read-disturb would primarily come into play when the second page is read, since it's adjacent to the first page (please correct me if I'm wrong there). Anyway, all 3 of these tests were run for at least 50 million read cycles, with no bit-flips detected. So I'm somewhat doubtful that this is the cause of the BBT corruption I've been seeing. ==== Separately, I set up 2 test devices to run while I was away last week. One of them contained 2 patches: - Mike Hench's patch which eliminates this block of code in fsl_elbc_nand.c - Adam Thomson's patch (http://lists.infradead.org/pipermail/linux-mtd/2011-June/036427.html) which initializes oob_poi correctly Upon my return, the device with these patches saw no problems at all, and had no additional bad blocks. The device without these patches had some 200+ blocks which had been newly marked as bad in the BBT over the course of 10 days. After rebooting, this latter device then failed to boot, as shown here: http://mcreech.com/work/bbt-ecc-error4.txt I'm currently running another test to verify which of the two patches actually fixed this problem (which might take a few days), but it seems like removing that block of code in fsl_elbc_nand.c is a good idea. -- Matthew L. Creech _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
