During phase 1 of the resource allocation we gather all the size
requirements. Starting from the leafs of our devicetree, we cal-
culate the requirements per bus, until we reach the resource do-
main.
However, because alignment plays a role, we can't just accumulate
the sizes of all resources on a bus. Instead, we already sort all
the resources per bus to predict their relative placement, inclu-
ding alignment gaps. Then, phase 2 has to perform the final allo-
cations with the exact same relative placement.
This patch introduces a very simple mechanism to avoid repeating
all the calculations: In phase 1, we note the relative `base` of
each resource on a bus. And after we allocated all the resources
directly below the domain in phase 2, we add the absolute `base`
of bridge resources to the relative `base` of child resources.
This saves most of the computational complexity in phase 2. How-
ever, with a shallow devicetree with most devices directly below
the domain, this won't have a measurable impact.
Example after phase 1:
domain
|
`-- bridge #0
| res #0, base 0x000000 (relative),
| size 12M, align 8M
|
|-- device #0
| res #1, base 0x800000 (relative),
| size 4M, align 4M
|
`-- bridge #1
| res #2, base 0x000000 (relative),
| size 8M, align 8M
|
`-- device #1
res #3, base 0x000000 (relative),
size 8M, align 8M
After phase 2 allocation at the domain level (assuming res #0 got
0xa000000 assigned):
domain
|
`-- bridge #0
| res #0, base 0xa000000 (absolute),
| size 12M, align 8M
|
|-- device #0
| res #1, base 0x800000 (relative),
| size 4M, align 4M
|
`-- bridge #1
| res #2, base 0x000000 (relative),
| size 8M, align 8M
|
`-- device #1
res #3, base 0x000000 (relative),
size 8M, align 8M
Now, all we need to do is to add the `base` of bridge resources
recursively. Starting with resources on the bus below bridge #0:
domain
|
`-- bridge #0
| res #0, base 0xa000000 (absolute),
| size 12M, align 8M
|
|-- device #0
| res #1, base 0xa800000 (absolute),
| size 4M, align 4M
|
`-- bridge #1
| res #2, base 0xa000000 (absolute),
| size 8M, align 8M
|
`-- device #1
res #3, base 0x000000 (relative),
size 8M, align 8M
And finally for resources on the bus below bridge #1:
domain
|
`-- bridge #0
| res #0, base 0xa000000 (absolute),
| size 12M, align 8M
|
|-- device #0
| res #1, base 0xa800000 (absolute),
| size 4M, align 4M
|
`-- bridge #1
| res #2, base 0xa000000 (absolute),
| size 8M, align 8M
|
`-- device #1
res #3, base 0xa000000 (absolute),
size 8M, align 8M
Change-Id: I70c700318a85f6760f27597730bc9c9a86dbe6b3
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65420
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
9260ea60bf