readme.h6-libdram

the allwinner h6 u-boot has routines to calculate the dram timing automatically which
works well for most boards and tv-boxes, but for me it failed on some still (maybe cheap
and out-of-spec memory chips?) and it was not possible to get mainline u-boot working
on those h6 tv boxes. there is a special and very hacky way to build a mainline u-boot
using an allwinner bsp binary blob for the memory timing calculation instead which so
far worked on all those tv boxes ... some remarks regarding this method:

- the resulting u-boot cannot be redistrbuted, as it would break the gpl of mainline
  u-boot as it would mix it with the binary blob into one binary - as a result one
  will have to build it one-self in order to test if the blob can find a valid memory
  timing
- the process to build it is _very_ complicated: one has to build u-boot two times:
  once on a 32bit arm system and another time on a 64bit arm system using one result
  of the 32bit from before
- this setup can only detect up to 2gb or ram, even if the box has more (allwinner h6
  can address at max 3gb of ram only anyway so one can loose 1gb in the worst case)

# 32bit part - to be done on an armv7l 32bit arm machine

# needed for u-boot compile
apt-get install swig
git clone https://github.com/apritzel/u-boot.git
mv u-boot u-boot-mainline-h6-apritzel-32bit-part
cd u-boot-mainline-h6-apritzel-32bit-part
git checkout eachlink-h6-mini-WIP
patch -p1 < /compile/doc/u-boot-misc/misc.h6-libdram/spl_switch-32bit.patch
# get bl31.bin and libdram via
tar xvzf H6-BSP-1.0.tgz lichee/tools/pack/chips/sun50iw6p1/bin/bl31.bin lichee/bootloader/uboot_2014_sunxi_spl/sunxi_spl/dram/sun50iw6p1/dram/libdram
# the old BSP link does not work anymore - see below for a working one
# no more working link: http://files.pine64.org/os/sdk/H64-ver1.0/H6-BSP-1.0.tgz (via: https://wiki.pine64.org/index.php/PINE_H64_Main_Page#Linux_BSP_SDK)
# working link: http://dl.linux-sunxi.org/H6/H6-BSP-1.0.tgz
cp lichee/tools/pack/chips/sun50iw6p1/bin/bl31.bin .
cp lichee/bootloader/uboot_2014_sunxi_spl/sunxi_spl/dram/sun50iw6p1/dram/libdram .
mv libdram libdram-h6
make eachlink_h6_mini_libdram_spl_defconfig
make
# scp spl/sunxi-spl.bin over to 64bit machine for 64bit part as sunxi-spl.bin-arm32

# for pure 32bit u-boot:
# - use u-boot-sunxi-with-spl.bin
# - dd if=u-boot-sunxi-with-spl.bin of=/dev/sdx bs=1024 seek=8
# ==> does not seem to make sense, as it does not seem to include the atf

# alternative libdram - did not work for me
# from: https://github.com/orangepi-xunlong/OrangePiH6_uboot/blob/master/sunxi_spl/dram/sun50iw6p1/dram/libdram
# via: https://forum.armbian.com/topic/12372-h6-allwinner-tv-box-need-help/?do=findComment&comment=92503

# 64bit part - to be done on an aarch64 64bit arm machine

# needed for u-boot compile
apt-get install swig
git clone https://github.com/apritzel/u-boot.git
mv u-boot u-boot-mainline-h6-apritzel-64bit-part
cd u-boot-mainline-h6-apritzel-64bit-part
make eachlink_h6_mini_defconfig
make
# i think this one did not work - too long ago ...
#cat sunxi-spl.bin-arm32 u-boot.img u-boot.dtb > my-u-boot.dd
cat sunxi-spl.bin-arm32 u-boot.itb > my-u-boot.dd
dd my-u-boot.dd of=/dev/sdX bs=1024 seek=8

# see also:
https://forum.armbian.com/topic/10174-since-tanix-tx6-can-boot-from-the-sd-card/?do=findComment&comment=80301
https://forum.armbian.com/topic/10174-since-tanix-tx6-can-boot-from-the-sd-card/?do=findComment&comment=80354
https://github.com/apritzel/u-boot/issues/4

# some more interesting read:
https://freenode.irclog.whitequark.org/linux-sunxi/2020-08-02
https://freenode.irclog.whitequark.org/linux-sunxi/2020-08-03
https://freenode.irclog.whitequark.org/linux-sunxi/2020-08-04
https://freenode.irclog.whitequark.org/linux-sunxi/2020-08-11