[PATCH 1/1] riscv: remove dram_init_banksize()

[Wu, Fei]

On 9/26/2023 3:16 PM, Heinrich Schuchardt wrote:
> Remove dram_init_banksize() on the architecture level.
> 
> Limiting used RAM to under 4 GiB is only necessary for CPUs which have a
> DMA issue. SoC specific code already exists for FU540, FU740, JH7110.
> 
> Not all RISC-V boards will have memory below 4 GiB.
> 
> A weak implementation of dram_init_banksize() exists in common/board_f.c.
> 
> See the discussion in
> https://lore.kernel.org/u-boot/545fe813-cb1e-469c-a131-0025c77aeaa2@canonical.com/T/
> 
Thanks you Heinrich, this patch itself is okay to me, but it still
doesn't address the problem in that thread. In setup_dest_addr():

#ifdef CFG_SYS_SDRAM_BASE
        gd->ram_base = CFG_SYS_SDRAM_BASE;
#endif
        gd->ram_top = gd->ram_base + get_effective_memsize();
        gd->ram_top = board_get_usable_ram_top(gd->mon_len);

ram_base is modified in #ifdef so that ram_base and
get_effective_memsize() is not well paired. e.g. two ranges of memory
[2GB, 3GB) and [4GB, 6GB), ram_base is set to 2GB of 1st range and
get_effective_memsize() returns 2GB of 2nd range, ram_top will be set to
4GB which is not desired. Will you address this too?

Best Regards,
Fei.

> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
>  arch/riscv/cpu/generic/dram.c | 16 ----------------
>  1 file changed, 16 deletions(-)
> 
> diff --git a/arch/riscv/cpu/generic/dram.c b/arch/riscv/cpu/generic/dram.c
> index 94d8018407..1b51bae9b6 100644
> --- a/arch/riscv/cpu/generic/dram.c
> +++ b/arch/riscv/cpu/generic/dram.c
> @@ -20,19 +20,3 @@ int dram_init_banksize(void)
>  {
>  	return fdtdec_setup_memory_banksize();
>  }
> -
> -phys_addr_t board_get_usable_ram_top(phys_size_t total_size)
> -{
> -	/*
> -	 * Ensure that we run from first 4GB so that all
> -	 * addresses used by U-Boot are 32bit addresses.
> -	 *
> -	 * This in-turn ensures that 32bit DMA capable
> -	 * devices work fine because DMA mapping APIs will
> -	 * provide 32bit DMA addresses only.
> -	 */
> -	if (gd->ram_top >= SZ_4G)
> -		return SZ_4G - 1;
> -
> -	return gd->ram_top;
> -}