Hi Simon,
This is not the topic about disable the relocate feature in U-Boot
proper.
My target is re-use kernel dtb in U-Boot and U-Boot can work properly
even if
some of dts node in kernel is broken.
- U-Boot mark a set of driver as u-boot,dm-pre-reloc, suppose to able to get
into U-Boot shell with them. dram, syscon, serial, clock, pinctrl,
emmc, and etc.
In this case we can always make U-Boot works and get into shell.
- When relocate, I would like to read dtb from kernel and use it for
U-Boot driver.
In this case, we can get periph driver setting for different board
from kernel dtb,
what we need most are: power/pmic, display, charger, input key and etc.
The problem is, the dm architecture now always init all the driver from
dtb after relocate,
If anything missin in kernel dtb, the U-Boot hang there. What I met now
in rockchip
kernel(same in different SoCs) is:
- no stdout in chosen, we use cmdline instead;
- debug uart node not enabled; we may use ttyFIQ driver instead of uart
driver for it.
- no alias for emmc/sd, which is much in U-Boot;
- compaptible for syscon may different, kernel may use "syscon",
"simple-mfd" only,
but U-Boot need "rockchip,rk3228-grf" for GRF and
"rockchip,rk3228-PMU" for PMU and etc.
Of cause I can update kernel source, but as you can see we are not able
to cover all the case
because kernel may have different use with U-Boot.
If we do not need to re-init all the driver after relocate, or re-use
the driver data,
then we can have a *robust U-Boot only depends on U-Boot dtb with
dm-pre-reloc*,
and we can have a *good compatibility U-Boot with kernel dtb support*
for different board/periph.
Then U-Boot focus on SoC support, kernel focus on all kinds of
board/periph support,
U-Boot need to sync periph driver from kernel, so that if kernel works
then U-Boot also works, developers
do not need to develop one for kernel and one for U-Boot.
Could you help to make a demo patch about how to re-use the driver-data
of pre-reloc to post-reloc?
Thanks,
- Kever
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