[PATCH 2/2] board: rock5b-rk3588: add memory gaps into kernel's DTB

[Mark Kettenis]

> From: Eugen Hristev <eugen.hristev at collabora.com>
> Date: Thu, 16 Feb 2023 15:29:05 +0200
> 
> RK3588 has two memory gaps when using 16 GiB DRAM size:
> [0x3fc000000 , 0x3fc500000]
> and
> [0x3fff00000 , 0x3ffffffff]
> 
> If the kernel is agnostic to these gaps, accessing the area causes
> a SError panic.
> 
> Hence, add reserved memory areas in kernel's DTB before booting.

I can confirm that using the full 16GB of memory on the rock5b causes
prolems for OpenBSD as well.

Was wondering whether excluding these regions was better done by
adding reserved-memory nodes in the device tree though like what is
done in the meson-g12-common.dtsi file for example.

> Signed-off-by: Eugen Hristev <eugen.hristev at collabora.com>
> ---
> 
> Hi,
> 
> These memory gaps are required because the kernel crashes with a SError if
> accessing that area.
> It appears the ATAGs provide DDR banks that do not include those specific
> two regions.
> To be able to boot the kernel, those areas have to be reserved.
> Maybe someone from Rockchip could have an explanation to this behavior?
> Otherwise we have to block them at this level.
> If those memory ranges are reserved for a dedicated purpose we can come up
> with a better solution, w.r.t. the purpose of the regions.
> 
> Thanks !
> Eugen
> 
>  board/radxa/rock5b-rk3588/rock5b-rk3588.c | 35 +++++++++++++++++++++++
>  configs/rock5b-rk3588_defconfig           |  1 +
>  2 files changed, 36 insertions(+)
> 
> diff --git a/board/radxa/rock5b-rk3588/rock5b-rk3588.c b/board/radxa/rock5b-rk3588/rock5b-rk3588.c
> index b5d74798f3b9..5c3b52b94898 100644
> --- a/board/radxa/rock5b-rk3588/rock5b-rk3588.c
> +++ b/board/radxa/rock5b-rk3588/rock5b-rk3588.c
> @@ -2,3 +2,38 @@
>  /*
>   * Copyright (c) 2023 Collabora Ltd.
>   */
> +
> +#include <fdtdec.h>
> +#include <fdt_support.h>
> +
> +#ifdef CONFIG_OF_BOARD_SETUP
> +int rock5b_add_reserved_memory_fdt_nodes(void *new_blob)
> +{
> +	struct fdt_memory gap1 = {
> +		.start = 0x3fc000000,
> +		.end = 0x3fc4fffff,
> +	};
> +	struct fdt_memory gap2 = {
> +		.start = 0x3fff00000,
> +		.end = 0x3ffffffff,
> +	};
> +	unsigned long flags = FDTDEC_RESERVED_MEMORY_NO_MAP;
> +	unsigned int ret;
> +
> +	/*
> +	 * Inject the reserved-memory nodes into the DTS
> +	 */
> +	ret = fdtdec_add_reserved_memory(new_blob, "gap1", &gap1,  NULL, 0,
> +					 NULL, flags);
> +	if (ret)
> +		return ret;
> +
> +	return fdtdec_add_reserved_memory(new_blob, "gap2", &gap2,  NULL, 0,
> +					  NULL, flags);
> +}
> +
> +int ft_board_setup(void *blob, struct bd_info *bd)
> +{
> +	return rock5b_add_reserved_memory_fdt_nodes(blob);
> +}
> +#endif
> diff --git a/configs/rock5b-rk3588_defconfig b/configs/rock5b-rk3588_defconfig
> index 9b7db7de64be..f3026c7ea166 100644
> --- a/configs/rock5b-rk3588_defconfig
> +++ b/configs/rock5b-rk3588_defconfig
> @@ -26,6 +26,7 @@ CONFIG_FIT=y
>  CONFIG_FIT_VERBOSE=y
>  CONFIG_SPL_FIT_SIGNATURE=y
>  CONFIG_SPL_LOAD_FIT=y
> +CONFIG_OF_BOARD_SETUP=y
>  CONFIG_DEFAULT_FDT_FILE="rockchip/rk3588-rock-5b.dtb"
>  # CONFIG_DISPLAY_CPUINFO is not set
>  CONFIG_DISPLAY_BOARDINFO_LATE=y
> -- 
> 2.34.1
> 
>