[PATCH v2] ARM: dts: rainier,everest: Move reserved memory regions

Andrew Jeffery andrew at aj.id.au
Wed Sep 21 11:09:15 AEST 2022

On Sat, 17 Sep 2022, at 05:25, Adriana Kobylak wrote:
> From: Adriana Kobylak <anoo at us.ibm.com>
> Move the reserved regions to account for a decrease in DRAM when ECC is
> enabled. ECC takes 1/9th of memory.
> Running on HW with ECC off, u-boot prints:
> DRAM:  already initialized, 1008 MiB (capacity:1024 MiB, VGA:16 MiB, ECC:off)
> And with ECC on, u-boot prints:
> DRAM:  already initialized, 896 MiB (capacity:1024 MiB, VGA:16 MiB, 
> ECC:on, ECC size:896 MiB)
> This implies that MCR54 is configured for ECC to be bounded at the
> bottom of a 16MiB VGA memory region:
> 1024MiB - 16MiB (VGA) = 1008MiB
> 1008MiB / 9 (for ECC) = 112MiB
> 1008MiB - 112MiB = 896MiB (available DRAM)
> The flash_memory region currently starts at offset 896MiB:
> 0xb8000000 (flash_memory offset) - 0x80000000 (base memory address) = 
> 0x38000000 = 896MiB
> This is the end of the available DRAM with ECC enabled and therefore it
> needs to be moved.
> Since the flash_memory is 64MiB in size and needs to be 64MiB aligned,
> it can just be moved up by 64MiB and would sit right at the end of the
> available DRAM buffer.
> The ramoops region currently follows the flash_memory, but it can be
> moved to sit above flash_memory which would minimize the address-space
> fragmentation.
> Signed-off-by: Adriana Kobylak <anoo at us.ibm.com>

Reviewed-by: Andrew Jeffery <andrew at aj.id.au>

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