Bin Meng bmeng.cn@gmail.com 於 2018年11月21日 週三 下午3:18寫道：
Hi Rick,
On Wed, Nov 21, 2018 at 2:00 PM Rick Chen rickchen36@gmail.com wrote:
Do any of your above patches get v2 posted? At least I did not see any follow-up response [1] regarding to "riscv: ax25-ae350: Pass dtb address to u-boot with a1 register"
First of all you told me about that board_fdt_blob_setup() should be completely removed. Instead the simple fix should be add CONFIG_OF_PRIOR_STAGE to ax25-ae350_defconfig.
Then I explain you about that is for booting from flash. And you said In this case, we need support OF_CONTROL like other arch, eg: CONFIG_OF_EMBED and CONFIG_OF_SEPARATE.
In README, I don't find the limitation about when booting from flash, it can not use CONFIG_OF_BOARD.
Correct. However, when ax25-ae350's U-Boot boots from ROM, where does prior_stage_fdt_address get assigned to the ROM address? Besides, this variable is declared in fdtdec.h as follows:
#if CONFIG_IS_ENABLED(OF_PRIOR_STAGE) extern phys_addr_t prior_stage_fdt_address; #endif
It means only OF_PRIOR_STAGE will use this variable. But in your patch
I have seen that declaration in fdtdec.h But I was referred to include\configs\bcmstb.h extern phys_addr_t prior_stage_fdt_address; and that is why I borrow prior_stage_fdt_address.
You do not point out this consideration directly, maybe that is why we have some thinking is different.
this was borrowed to support OF_BOARD, which is confusing I think. If U-Boot boots from reset vector, the canonical way to support DT is via CONFIG_OF_EMBED or CONFIG_OF_SEPARATE.
That is why ax25-ae350 use CONFIG_OF_BOARD to support boot from RAM and ROM. It is a flexible approach to meet Andes' HW mechanism.
I think it is a configuration in ax25-ae350_defconfig. It will not affect qemu-riscv32(64)_defconfig.
I understand it does not affect qemu riscv board. The thing is that I wasn't clear why you did that way for ax25-ae350.
Actually I just want to remove the redundant code in start.S - li t0, CONFIG_SYS_SDRAM_BASE - SREG a2, 0(t0) so borrowed prior_stage_fdt_address in CONFIG_OF_BOARD
Rick
That is why I do not prepare v2 to modify it as CONFIG_OF_EMBED or CONFIG_OF_SEPARATE as your willingness.
Regards, Bin