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- Allwinner NAND flashing
- =======================
- A lot of Allwinner devices, especially the older ones (pre-H3 era),
- comes with a NAND. NANDs storages are a pretty weak choice when it
- comes to the reliability, and it comes with a number of flaws like
- read and write disturbs, data retention issues, bloks becoming
- unusable, etc.
- In order to mitigate that, various strategies have been found to be
- able to recover from those issues like ECC, hardware randomization,
- and of course, redundancy for the critical parts.
- This is obviously something that we will take into account when
- creating our images. However, the BROM will use a quite weird pattern
- when accessing the NAND, and will access only at most 4kB per page,
- which means that we also have to split that binary accross several
- pages.
- In order to accomodate that, we create a tool that will generate an
- SPL image that is ready to be programmed directly embedding the ECCs,
- randomized, and with the necessary bits needed to reduce the number of
- bitflips. The U-Boot build system, when configured for the NAND (with
- CONFIG_MTD_RAW_NAND=y) will also generate the image sunxi-spl-with-ecc.bin
- that will have been generated by that tool.
- In order to flash your U-Boot image onto a board, assuming that the
- board is in FEL mode, you'll need the sunxi-tools that you can find at
- this repository: https://github.com/linux-sunxi/sunxi-tools
- Then, you'll need to first load an SPL to initialise the RAM:
- sunxi-fel spl spl/sunxi-spl.bin
- Load the binaries we'll flash into RAM:
- sunxi-fel write 0x4a000000 u-boot-dtb.bin
- sunxi-fel write 0x43000000 spl/sunxi-spl-with-ecc.bin
- And execute U-Boot
- sunxi-fel exe 0x4a000000
- On your board, you'll now have all the needed binaries into RAM, so
- you only need to erase the NAND...
- nand erase.chip
- Then write the SPL and its backup:
- nand write.raw.noverify 0x43000000 0 40
- nand write.raw.noverify 0x43000000 0x400000 40
- And finally write the U-Boot binary:
- nand write 0x4a000000 0x800000 0xc0000
- You can now reboot and enjoy your NAND.
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