Commit c214e564 authored Jul 24, 2020 by Brian Norris Committed by Enric Balletbo i Serra Jul 31, 2020

platform/chrome: cros_ec_proto: ignore unnecessary wakeups on old ECs

ECs that don't implement EC_CMD_HOST_EVENT_GET_WAKE_MASK should still
have some reasonable default mask -- otherwise, they'll treat a variety
of EC signals as spurious wakeups. Battery and AC events can be
especially common, for devices that have been sitting at full charge
plugged into AC for a long time, as they may cycle their charging off
and on, or their battery may start reporting failures as it ages.

Treating these as wakeups does not serve a useful purpose, and is
instead often counterproductive. And indeed, later ECs (that implement
the mask) don't include these events in their wake-mask.

Note that this patch doesn't do anything without the subsequent patch
("platform/chrome: cros_ec_proto: check for missing
EC_CMD_HOST_EVENT_GET_WAKE_MASK"), because
cros_ec_get_host_event_wake_mask() currently does not return an error if
EC_CMD_HOST_EVENT_GET_WAKE_MASK is not implemented.

Some additional notes:
While the EC typically knows not to wake the CPU for these unimportant
events once the CPU reaches a sleep state, it doesn't really have a way
to know that the CPU is "almost" asleep, unless it has support for
EC_CMD_HOST_SLEEP_EVENT. Alas, these older ECs do not support that
command either, so this solution is not 100% complete.

Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

parent 7f4784f1

drivers/platform/chrome/cros_ec_proto.c

+18 −6

Original line number	Diff line number	Diff line
		@@ -469,14 +469,26 @@ int cros_ec_query_all(struct cros_ec_device *ec_dev)
		&ver_mask);
		ec_dev->host_sleep_v1 = (ret >= 0 && (ver_mask & EC_VER_MASK(1)));

		/*
		* Get host event wake mask, assume all events are wake events
		* if unavailable.
		*/
		/* Get host event wake mask. */
		ret = cros_ec_get_host_event_wake_mask(ec_dev, proto_msg,
		&ec_dev->host_event_wake_mask);
		if (ret < 0)
		ec_dev->host_event_wake_mask = U32_MAX;
		if (ret < 0) {
		/*
		* If the EC doesn't support EC_CMD_HOST_EVENT_GET_WAKE_MASK,
		* use a reasonable default. Note that we ignore various
		* battery, AC status, and power-state events, because (a)
		* those can be quite common (e.g., when sitting at full
		* charge, on AC) and (b) these are not actionable wake events;
		* if anything, we'd like to continue suspending (to save
		* power), not wake up.
		*/
		ec_dev->host_event_wake_mask = U32_MAX &
		~(BIT(EC_HOST_EVENT_AC_DISCONNECTED) \|
		BIT(EC_HOST_EVENT_BATTERY_LOW) \|
		BIT(EC_HOST_EVENT_BATTERY_CRITICAL) \|
		BIT(EC_HOST_EVENT_PD_MCU) \|
		BIT(EC_HOST_EVENT_BATTERY_STATUS));
		}

		ret = 0;

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