On Wed, Apr 11, 2012 at 9:22 PM, Scott Wood <scottw...@freescale.com> wrote:
> On 04/11/2012 07:14 PM, Rafael Beims wrote: > >> Hello Scott, >> On Wed, Apr 11, 2012 at 6:54 PM, Scott Wood <scottw...@freescale.com >> <mailto:scottwood@freescale.**com <scottw...@freescale.com>>> wrote: >> >> On 04/11/2012 04:28 PM, Rafael Beims wrote: >> >> Hello, >> I work with several MPC83xx boards in our company, and a while >> ago we were >> informed that the NAND chip we used was being discontinued. The >> only >> options for a replacement were the newer 4k page ones. >> Specifically, we are >> using now the Micron 29F8G08ABABA (8 gigabit). >> >> I was sweeping the repositories and this list's archives and I'm >> with the >> impression that these chips are not supported yet. I saw some >> patches sent >> hacking the driver to allow for the use of 4k pages. >> >> Additionally, I'm worried about the use of the 4 bit ECC lib >> (BCH), as it >> seems to me that the fsl_elbc_nand driver is not prepared to use >> a software >> ECC config. Maybe I'm wrong, but it seems that the driver always >> uses the 1 >> bit HW ECC that's present in freescale's controller. >> >> Because of this, I would like to ask for an overall status of >> these things. >> What can I expect to be working? What are the main areas of >> concern? >> If there is no complete implementation yet (as I saw some >> patches being >> rejected / not merged yet), what is currently missing? >> What is the area where most work is needed? >> >> >> The main thing that is missing from the current patches is migrating >> bad block markers on first use, and checking that this has happened >> before using the hack. See the discussion on the Linux version of >> these patches. I was hoping to take care of this earlier this year, >> but other tasks have intruded. >> >> >> Does this have to do with the fact that the oob size is different in the >> bigger page NAND's (sorry if my question seems dumb, but I'm not very >> familiar with the NAND drivers and the software use. Until now the NAND >> part was just plug and play :) ) >> > > The hack involves changing the flash layout from "4096 main 128 spare" to > "2048 main 64 spare 2048 main 64 spare". This means that the factory bad > block marker is now in an area we use for main data. We need to move it to > where it belongs in the new layout before doing anything else with the chip. > > > And as you note, many 4K-page NAND chips require 4-bit ECC which >> means the driver will need to be updated to support software ECC >> (this should be fairly straightforward, except maybe the decision of >> when to do this). >> >> -Scott >> >> >> I will have a look at the driver and try to do the modifications to >> support SW ECC. As I understand the fsl_elbc_nand driver is in sync with >> the linux kernel, and in this case the patches should be implemented and >> sent to the kernel first? >> > > Ordinarily yes, but in this case it might be better to start with U-Boot. > We'll likely do the bad block migration in U-Boot, whereas Linux will just > check that it's been done via some sort of marker. And the ECC stuff > doesn't make much sense until we have the 4K support (I haven't heard of a > 2K chip that needs 4-bit ECC). > > -Scott > > OK, I will have a look at it. I was just wondering, is there a tree somewhere that contains the patches for the 4k hack applied? I saw that a version 2 of the patch was sent by Shengzhou Liu in December 12, 2011, but I cannot find these patches applied in the main git:// git.denx.de/u-boot-nand-flash.git. I think that has something to do with the fact that the patches were not accepted in the way that they were presented, but I would like to know what's the procedure to start working from there to a possible solution. I even tried to apply the patches to the current tree, without success. I could manually apply them, but this code is not mine and if I manually applied it, it would appear as mine. Thanks for the support so far, Rafael
_______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
