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author | Samuel Holland <samuel@sholland.org> | 2023-01-23 09:32:07 +0300 |
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committer | Anup Patel <anup@brainfault.org> | 2023-01-24 15:00:21 +0300 |
commit | c45992cc2b121e05c74b438462b8066de3e7d999 (patch) | |
tree | 3e89e9b3349613a2f4ca917959155c2147291d5e /docs | |
parent | 33bf9174602c900201481241e9ade31cf37fccd8 (diff) | |
download | opensbi-c45992cc2b121e05c74b438462b8066de3e7d999.tar.xz |
platform: generic: allwinner: Advertise nonretentive suspend
Add D1's nonretentive suspend state to the devicetree so S-mode software
knows about it and can use it.
Latency and power measurements were taken on an Allwinner Nezha board:
- Entry latency was measured from the beginning of sbi_ecall_handler()
to before the call to wfi() in sun20i_d1_hart_suspend().
- Exit latency was measured from the beginning of sbi_init() to before
the call to sbi_hart_switch_mode() in init_warmboot().
- There was a 17.5 mW benefit from non-retentive suspend compared to
WFI, with a 170 mW cost during the 107 us entry/exit period. This
provides a break-even point around 1040 us. Residency includes entry
latency, so round this up to 1100 us.
- The hardware power sequence latency (after the WFI) is assumed to be
negligible, so set the wakeup latency to the exit latency.
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Diffstat (limited to 'docs')
0 files changed, 0 insertions, 0 deletions