[PATCH v3 2/3] rockchip: sdram: Limit usable ram_top to max 4G

[Kever Yang]

On 2025/1/31 06:07, Jonas Karlman wrote:
> U-Boot only works correctly when it uses RAM below the 4G address
> boundary on Rockchip SoCs. Limit usable gd->ram_top to max 4G.
>
> Signed-off-by: Jonas Karlman <jonas at kwiboo.se>
Reviewed-by: Kever Yang <kever.yang at rock-chips.com>

Thanks,
- Kever
> ---
> v3: Use u64 to fix 32-bit overflow
> v2: New patch
> ---
>   arch/arm/mach-rockchip/sdram.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/mach-rockchip/sdram.c b/arch/arm/mach-rockchip/sdram.c
> index 96a791bda2c3..4b8b6b9da7c5 100644
> --- a/arch/arm/mach-rockchip/sdram.c
> +++ b/arch/arm/mach-rockchip/sdram.c
> @@ -487,7 +487,8 @@ int dram_init(void)
>   
>   phys_addr_t board_get_usable_ram_top(phys_size_t total_size)
>   {
> -	unsigned long top = CFG_SYS_SDRAM_BASE + SDRAM_MAX_SIZE;
> +	/* Make sure U-Boot only uses the space below the 4G address boundary */
> +	u64 top = min_t(u64, CFG_SYS_SDRAM_BASE + SDRAM_MAX_SIZE, SZ_4G);
>   
>   	return (gd->ram_top > top) ? top : gd->ram_top;
>   }