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

[Mark Kettenis]

> Date: Tue, 21 Feb 2023 10:35:18 +0200
> From: Eugen Hristev <eugen.hristev at collabora.com>
> 
> On 2/21/23 00:47, Mark Kettenis wrote:
> >> 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.
> 
> But does it work fine with this patch ?

Yes, it does.

> >> 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
> >>
> >>
> 
>