On Tue, Dec 01, 2009 at 01:06:07PM -0500, [email protected] wrote: > +MTD NAND 64 bit support: > +======================== > + > +The MTD NAND infrastructure in U-Boot(until release 2009.11) used only > +32 bit values to represent device size. As a result of which if we use > +a NAND device of size 4 GB and above, the MTD NAND driver will not detect > +such a NAND device due to overflow. > +NANDs comes in various flavours. There are some NANDs which are > +internally 2 devices and have 2 chipselects. If the SOC specific > +NAND driver is designed to treat each NAND device as a separate device > +then we will still be able to detect the entire 4GB of a NAND device. > +Each chipselect being responsible for 2 GB address space. > +But if at the U-Boot level we want to have access to the entire 4GB address > +space then the only way to achieve this is to update the MTD and NAND drivers > +with 64 bit values. > +The Linux kernel was updated with 64 bit values sometime in December '08. > +The core NAND driver is now similar to the core NAND driver in the kernel. > +We appropriately update the MTD layer in U-Boot. > +In the process of syncing up with the kernel we have also updated the > +NAND driver with other enhancements that made its way to the NAND driver. > + > +After these features were added, testing was performed on a wide > +range of NAND devices with page size of 64 KiB, 128KiB, 256KiB and 512 > +KiB. Also 2 separate 4GB NAND devices(one from SAMSUNG and one from MICRON) > +were successfully tested. U-Boot was able to correctly detect the device > +and read bad blocks.
Hmm, not sure we need to describe here what was, rather than what is. > +What is lacking? > +================ > + > +We need to add 64 bit support in cmd_nand.c and env_nand.c as well. > +Without this certain diagnostcis typo > will fail. For example, > +issuing a "nand bad" command results in the same bad blocks being > +found infinite times. This happens if we use a 4 GB NAND device. > +This will not occur if NANDs of smalles than 4 GB are used. s/of smalles than/smaller than/ > +At this point of time it appears as if the entire common folder > +needs to be updated with 64 bit values. Yeah... If you want to put a concise note about this here, I'll add it, though an actual bug tracking system would be nice. :-) -Scott _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
