Messages in this thread | | | Date | Sat, 18 Mar 2023 21:17:40 +0800 | Subject | Re: [PATCH 11/15] arm64: dts: nuvoton: Add initial ma35d1 device tree | From | Jacky Huang <> |
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Dear Arnd,
Thanks for your suggestion.
On 2023/3/16 下午 10:17, Arnd Bergmann wrote: > On Wed, Mar 15, 2023, at 08:28, Jacky Huang wrote: >> + mem: memory@80000000 { >> + device_type = "memory"; >> + reg = <0x00000000 0x80000000 0 0x20000000>; /* 512M DRAM */ >> + }; >> +}; > In most machines, the memory size is detected by the boot loader > and filled in the dtb in memory before starting the kernel, so > you should not need two separate files here for the two common > memory configurations.
On ma35d1, memory size is determined early before uboot.
BL1 (MaskROM boot code) -> BL2 (arm-trust-firmware) -> BL32 (op-tee) & BL33 (uboot).
The DDR was initialized in BL2 stage with a selected DDR setting, which
is hard coded, including DDR size.
We searched the arm64 dts and found that almost all vendors claimed
memory size in board level dtsi/dts. This seems to be common.
So, can we have it unchanged?
> Since the machine is called 'som', I would assume that this is a > module that is integrated on another board, so more commonly one > would have a dtsi file for the som in addition to the one for the > soc, and have all the components of the module listed in this > file, while the dts file that includes the som.dtsi lists the > devices on the carrier board and enables the on-chip devices > that are connected to the outside. > > Arnd
You are right, ma35d1 som have a base board, and a cpu board on it.
It is a good suggestion that we should have a dtsi for som base board.
Consider that we are in the initial submit, and such a dtsi will be an empty
file at this stage. So, I would like to do it when peripheral drivers
upstream started. Is it ok?
Best regards,
Jacky Huang
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