diff options
| author | Raul E Rangel <rrangel@chromium.org> | 2018-08-20 13:03:45 -0600 |
|---|---|---|
| committer | Martin Roth <martinroth@google.com> | 2018-09-12 14:15:48 +0000 |
| commit | 9fc7b8e973fca05381be66e7053ffa301c9dbe33 (patch) | |
| tree | cc31fca29d6e6afede855ca249e3de3a69da8dce /payloads/libpayload | |
| parent | 370c116ca5fa9e9d04ed61f445debde882b6a1cb (diff) | |
libpayload/x86/delay: Make arch_ndelay call apic_delay if delay is long
This reduces power consumption on grunt by over 3W when sitting at the
depthcharge recovery screen.
BUG=b:109749762
TEST=Booted grunt in the recovery screen and made sure it continued to
work.
Change-Id: Id079c099ee4cf6a07724241af4400063f4551668
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Reviewed-on: https://review.coreboot.org/28245
Reviewed-by: Martin Roth <martinroth@google.com>
Reviewed-by: Richard Spiegel <richard.spiegel@silverbackltd.com>
Reviewed-by: Julius Werner <jwerner@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Diffstat (limited to 'payloads/libpayload')
| -rw-r--r-- | payloads/libpayload/arch/x86/apic.c | 2 | ||||
| -rw-r--r-- | payloads/libpayload/arch/x86/delay.c | 12 |
2 files changed, 14 insertions, 0 deletions
diff --git a/payloads/libpayload/arch/x86/apic.c b/payloads/libpayload/arch/x86/apic.c index 079f456eec..99eff27aad 100644 --- a/payloads/libpayload/arch/x86/apic.c +++ b/payloads/libpayload/arch/x86/apic.c @@ -210,6 +210,8 @@ static void apic_init_timer(void) /* Set APIC init counter to MAX and count for 1 ms */ apic_write32(APIC_TIMER_INIT_COUNT, UINT32_MAX); + /* This is safe because apic_initialized() returns false so + * arch_ndelay() falls back to a busy loop. */ mdelay(1); ticks_per_ms = diff --git a/payloads/libpayload/arch/x86/delay.c b/payloads/libpayload/arch/x86/delay.c index 541cf7a436..19931fbc04 100644 --- a/payloads/libpayload/arch/x86/delay.c +++ b/payloads/libpayload/arch/x86/delay.c @@ -28,6 +28,7 @@ */ #include <libpayload.h> +#include <arch/apic.h> /* The pause instruction can delay 10-140 CPU cycles, so avoid calling it when * getting close to finishing. Depending on the timer source, the timer can be @@ -35,12 +36,23 @@ * that the timer is running at the CPU frequency. */ #define PAUSE_THRESHOLD_TICKS 150 +/* Let's assume APIC interrupts take at least 100us */ +#define APIC_INTERRUPT_LATENCY_NS (100 * NSECS_PER_USEC) + + void arch_ndelay(uint64_t ns) { uint64_t delta = ns * timer_hz() / NSECS_PER_SEC; uint64_t pause_delta = 0; + uint64_t apic_us = 0; uint64_t start = timer_raw_value(); + if (ns > APIC_INTERRUPT_LATENCY_NS) + apic_us = (ns - APIC_INTERRUPT_LATENCY_NS) / NSECS_PER_USEC; + + if (IS_ENABLED(CONFIG_LP_ENABLE_APIC) && apic_initialized() && apic_us) + apic_delay(apic_us); + if (delta > PAUSE_THRESHOLD_TICKS) pause_delta = delta - PAUSE_THRESHOLD_TICKS; |