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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>
This commit is contained in:
Samuel Holland 2023-01-23 00:32:07 -06:00 committed by Anup Patel
parent 33bf917460
commit c45992cc2b
1 changed files with 20 additions and 0 deletions
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20
platform/generic/allwinner/sun20i-d1.c
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@ -12,6 +12,7 @@
#include <sbi/sbi_error.h>
#include <sbi/sbi_hsm.h>
#include <sbi/sbi_pmu.h>
#include <sbi_utils/fdt/fdt_fixup.h>
#include <sbi_utils/fdt/fdt_helper.h>
#include <sbi_utils/irqchip/fdt_irqchip_plic.h>
@ -202,6 +203,24 @@ static int sun20i_d1_final_init(bool cold_boot, const struct fdt_match *match)
return 0;
}
static const struct sbi_cpu_idle_state sun20i_d1_cpu_idle_states[] = {
{
.name = "cpu-nonretentive",
.suspend_param = SBI_HSM_SUSPEND_NON_RET_DEFAULT,
.local_timer_stop = true,
.entry_latency_us = 40,
.exit_latency_us = 67,
.min_residency_us = 1100,
.wakeup_latency_us = 67,
},
{ }
};
static int sun20i_d1_fdt_fixup(void *fdt, const struct fdt_match *match)
{
return fdt_add_cpu_idle_states(fdt, sun20i_d1_cpu_idle_states);
}
static void thead_c9xx_pmu_ctr_enable_irq(uint32_t ctr_idx)
{
unsigned long mip_val;
@ -265,5 +284,6 @@ static const struct fdt_match sun20i_d1_match[] = {
const struct platform_override sun20i_d1 = {
.match_table = sun20i_d1_match,
.final_init = sun20i_d1_final_init,
.fdt_fixup = sun20i_d1_fdt_fixup,
.extensions_init = sun20i_d1_extensions_init,
};