services/surfaceflinger/DisplayHardware/PowerAdvisor.cpp

/*
 * Copyright 2018 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

//#define LOG_NDEBUG 0

#define ATRACE_TAG ATRACE_TAG_GRAPHICS

#undef LOG_TAG
#define LOG_TAG "PowerAdvisor"

#include <unistd.h>
#include <cinttypes>
#include <cstdint>
#include <optional>

#include <android-base/properties.h>
#include <utils/Log.h>
#include <utils/Mutex.h>
#include <utils/Trace.h>

#include <android/hardware/power/1.3/IPower.h>
#include <android/hardware/power/IPowerHintSession.h>
#include <android/hardware/power/WorkDuration.h>

#include <binder/IServiceManager.h>

#include "../SurfaceFlingerProperties.h"

#include "PowerAdvisor.h"
#include "SurfaceFlinger.h"

namespace android {
namespace Hwc2 {

PowerAdvisor::~PowerAdvisor() = default;

namespace impl {

namespace V1_0 = android::hardware::power::V1_0;
namespace V1_3 = android::hardware::power::V1_3;
using V1_3::PowerHint;

using android::hardware::power::Boost;
using android::hardware::power::IPower;
using android::hardware::power::IPowerHintSession;
using android::hardware::power::Mode;
using android::hardware::power::WorkDuration;

using scheduler::OneShotTimer;

PowerAdvisor::~PowerAdvisor() = default;

namespace {
std::chrono::milliseconds getUpdateTimeout() {
    // Default to a timeout of 80ms if nothing else is specified
    static std::chrono::milliseconds timeout =
            std::chrono::milliseconds(sysprop::display_update_imminent_timeout_ms(80));
    return timeout;
}

void traceExpensiveRendering(bool enabled) {
    if (enabled) {
        ATRACE_ASYNC_BEGIN("ExpensiveRendering", 0);
    } else {
        ATRACE_ASYNC_END("ExpensiveRendering", 0);
    }
}

} // namespace

PowerAdvisor::PowerAdvisor(SurfaceFlinger& flinger) : mFlinger(flinger) {
    if (getUpdateTimeout() > 0ms) {
        mScreenUpdateTimer.emplace("UpdateImminentTimer", getUpdateTimeout(),
                                   /* resetCallback */ nullptr,
                                   /* timeoutCallback */
                                   [this] {
                                       while (true) {
                                           auto timeSinceLastUpdate = std::chrono::nanoseconds(
                                                   systemTime() - mLastScreenUpdatedTime.load());
                                           if (timeSinceLastUpdate >= getUpdateTimeout()) {
                                               break;
                                           }
                                           // We may try to disable expensive rendering and allow
                                           // for sending DISPLAY_UPDATE_IMMINENT hints too early if
                                           // we idled very shortly after updating the screen, so
                                           // make sure we wait enough time.
                                           std::this_thread::sleep_for(getUpdateTimeout() -
                                                                       timeSinceLastUpdate);
                                       }
                                       mSendUpdateImminent.store(true);
                                       mFlinger.disableExpensiveRendering();
                                   });
    }
}

void PowerAdvisor::init() {
    // Defer starting the screen update timer until SurfaceFlinger finishes construction.
    if (mScreenUpdateTimer) {
        mScreenUpdateTimer->start();
    }
}

void PowerAdvisor::onBootFinished() {
    mBootFinished.store(true);
}

void PowerAdvisor::setExpensiveRenderingExpected(DisplayId displayId, bool expected) {
    if (expected) {
        mExpensiveDisplays.insert(displayId);
    } else {
        mExpensiveDisplays.erase(displayId);
    }

    const bool expectsExpensiveRendering = !mExpensiveDisplays.empty();
    if (mNotifiedExpensiveRendering != expectsExpensiveRendering) {
        std::lock_guard lock(mPowerHalMutex);
        HalWrapper* const halWrapper = getPowerHal();
        if (halWrapper == nullptr) {
            return;
        }

        if (!halWrapper->setExpensiveRendering(expectsExpensiveRendering)) {
            // The HAL has become unavailable; attempt to reconnect later
            mReconnectPowerHal = true;
            return;
        }

        mNotifiedExpensiveRendering = expectsExpensiveRendering;
    }
}

void PowerAdvisor::notifyDisplayUpdateImminent() {
    // Only start sending this notification once the system has booted so we don't introduce an
    // early-boot dependency on Power HAL
    if (!mBootFinished.load()) {
        return;
    }

    if (mSendUpdateImminent.exchange(false)) {
        std::lock_guard lock(mPowerHalMutex);
        HalWrapper* const halWrapper = getPowerHal();
        if (halWrapper == nullptr) {
            return;
        }

        if (!halWrapper->notifyDisplayUpdateImminent()) {
            // The HAL has become unavailable; attempt to reconnect later
            mReconnectPowerHal = true;
            return;
        }

        if (mScreenUpdateTimer) {
            mScreenUpdateTimer->reset();
        } else {
            // If we don't have a screen update timer, then we don't throttle power hal calls so
            // flip this bit back to allow for calling into power hal again.
            mSendUpdateImminent.store(true);
        }
    }

    if (mScreenUpdateTimer) {
        mLastScreenUpdatedTime.store(systemTime());
    }
}

// checks both if it supports and if it's enabled
bool PowerAdvisor::usePowerHintSession() {
    // uses cached value since the underlying support and flag are unlikely to change at runtime
    return mPowerHintEnabled.value_or(false) && supportsPowerHintSession();
}

bool PowerAdvisor::supportsPowerHintSession() {
    // cache to avoid needing lock every time
    if (!mSupportsPowerHint.has_value()) {
        std::lock_guard lock(mPowerHalMutex);
        HalWrapper* const halWrapper = getPowerHal();
        mSupportsPowerHint = halWrapper->supportsPowerHintSession();
    }
    return *mSupportsPowerHint;
}

bool PowerAdvisor::isPowerHintSessionRunning() {
    return mPowerHintSessionRunning;
}

void PowerAdvisor::setTargetWorkDuration(int64_t targetDurationNanos) {
    if (!usePowerHintSession()) {
        ALOGV("Power hint session target duration cannot be set, skipping");
        return;
    }
    {
        std::lock_guard lock(mPowerHalMutex);
        HalWrapper* const halWrapper = getPowerHal();
        if (halWrapper != nullptr) {
            halWrapper->setTargetWorkDuration(targetDurationNanos - kTargetSafetyMargin.count());
        }
    }
}

void PowerAdvisor::sendActualWorkDuration(int64_t actualDurationNanos, nsecs_t timeStampNanos) {
    if (!mBootFinished || !usePowerHintSession()) {
        ALOGV("Actual work duration power hint cannot be sent, skipping");
        return;
    }
    {
        std::lock_guard lock(mPowerHalMutex);
        HalWrapper* const halWrapper = getPowerHal();
        if (halWrapper != nullptr) {
            halWrapper->sendActualWorkDuration(actualDurationNanos, timeStampNanos);
        }
    }
}

// needs to be set after the flag is known but before PowerAdvisor enters onBootFinished
void PowerAdvisor::enablePowerHint(bool enabled) {
    mPowerHintEnabled = enabled;
}

bool PowerAdvisor::startPowerHintSession(const std::vector<int32_t>& threadIds) {
    if (!usePowerHintSession()) {
        ALOGI("Power hint session cannot be started, skipping");
    }
    {
        std::lock_guard lock(mPowerHalMutex);
        HalWrapper* halWrapper = getPowerHal();
        if (halWrapper != nullptr && usePowerHintSession()) {
            halWrapper->setPowerHintSessionThreadIds(threadIds);
            mPowerHintSessionRunning = halWrapper->startPowerHintSession();
        }
    }
    return mPowerHintSessionRunning;
}

class HidlPowerHalWrapper : public PowerAdvisor::HalWrapper {
public:
    HidlPowerHalWrapper(sp<V1_3::IPower> powerHal) : mPowerHal(std::move(powerHal)) {}

    ~HidlPowerHalWrapper() override = default;

    static std::unique_ptr<HalWrapper> connect() {
        // Power HAL 1.3 is not guaranteed to be available, thus we need to query
        // Power HAL 1.0 first and try to cast it to Power HAL 1.3.
        sp<V1_3::IPower> powerHal = nullptr;
        sp<V1_0::IPower> powerHal_1_0 = V1_0::IPower::getService();
        if (powerHal_1_0 != nullptr) {
            // Try to cast to Power HAL 1.3
            powerHal = V1_3::IPower::castFrom(powerHal_1_0);
            if (powerHal == nullptr) {
                ALOGW("No Power HAL 1.3 service in system, disabling PowerAdvisor");
            } else {
                ALOGI("Loaded Power HAL 1.3 service");
            }
        } else {
            ALOGW("No Power HAL found, disabling PowerAdvisor");
        }

        if (powerHal == nullptr) {
            return nullptr;
        }

        return std::make_unique<HidlPowerHalWrapper>(std::move(powerHal));
    }

    bool setExpensiveRendering(bool enabled) override {
        ALOGV("HIDL setExpensiveRendering %s", enabled ? "T" : "F");
        auto ret = mPowerHal->powerHintAsync_1_3(PowerHint::EXPENSIVE_RENDERING, enabled);
        if (ret.isOk()) {
            traceExpensiveRendering(enabled);
        }
        return ret.isOk();
    }

    bool notifyDisplayUpdateImminent() override {
        // Power HAL 1.x doesn't have a notification for this
        ALOGV("HIDL notifyUpdateImminent received but can't send");
        return true;
    }

    bool supportsPowerHintSession() override { return false; }

    bool isPowerHintSessionRunning() override { return false; }

    void restartPowerHintSession() override {}

    void setPowerHintSessionThreadIds(const std::vector<int32_t>&) override {}

    bool startPowerHintSession() override { return false; }

    void setTargetWorkDuration(int64_t) override {}

    void sendActualWorkDuration(int64_t, nsecs_t) override {}

    bool shouldReconnectHAL() override { return false; }

    std::vector<int32_t> getPowerHintSessionThreadIds() override { return std::vector<int32_t>{}; }

    std::optional<int64_t> getTargetWorkDuration() override { return std::nullopt; }

private:
    const sp<V1_3::IPower> mPowerHal = nullptr;
};

AidlPowerHalWrapper::AidlPowerHalWrapper(sp<IPower> powerHal) : mPowerHal(std::move(powerHal)) {
    auto ret = mPowerHal->isModeSupported(Mode::EXPENSIVE_RENDERING, &mHasExpensiveRendering);
    if (!ret.isOk()) {
        mHasExpensiveRendering = false;
    }

    ret = mPowerHal->isBoostSupported(Boost::DISPLAY_UPDATE_IMMINENT, &mHasDisplayUpdateImminent);
    if (!ret.isOk()) {
        mHasDisplayUpdateImminent = false;
    }

    mSupportsPowerHint = checkPowerHintSessionSupported();
}

AidlPowerHalWrapper::~AidlPowerHalWrapper() {
    if (mPowerHintSession != nullptr) {
        mPowerHintSession->close();
        mPowerHintSession = nullptr;
    }
};

std::unique_ptr<PowerAdvisor::HalWrapper> AidlPowerHalWrapper::connect() {
    // This only waits if the service is actually declared
    sp<IPower> powerHal = waitForVintfService<IPower>();
    if (powerHal == nullptr) {
        return nullptr;
    }
    ALOGI("Loaded AIDL Power HAL service");

    return std::make_unique<AidlPowerHalWrapper>(std::move(powerHal));
}

bool AidlPowerHalWrapper::setExpensiveRendering(bool enabled) {
    ALOGV("AIDL setExpensiveRendering %s", enabled ? "T" : "F");
    if (!mHasExpensiveRendering) {
        ALOGV("Skipped sending EXPENSIVE_RENDERING because HAL doesn't support it");
        return true;
    }

    auto ret = mPowerHal->setMode(Mode::EXPENSIVE_RENDERING, enabled);
    if (ret.isOk()) {
        traceExpensiveRendering(enabled);
    }
    return ret.isOk();
}

bool AidlPowerHalWrapper::notifyDisplayUpdateImminent() {
    ALOGV("AIDL notifyDisplayUpdateImminent");
    if (!mHasDisplayUpdateImminent) {
        ALOGV("Skipped sending DISPLAY_UPDATE_IMMINENT because HAL doesn't support it");
        return true;
    }

    auto ret = mPowerHal->setBoost(Boost::DISPLAY_UPDATE_IMMINENT, 0);
    return ret.isOk();
}

// only version 2+ of the aidl supports power hint sessions, hidl has no support
bool AidlPowerHalWrapper::supportsPowerHintSession() {
    return mSupportsPowerHint;
}

bool AidlPowerHalWrapper::checkPowerHintSessionSupported() {
    int64_t unused;
    // Try to get preferred rate to determine if hint sessions are supported
    // We check for isOk not EX_UNSUPPORTED_OPERATION to lump together errors
    return mPowerHal->getHintSessionPreferredRate(&unused).isOk();
}

bool AidlPowerHalWrapper::isPowerHintSessionRunning() {
    return mPowerHintSession != nullptr;
}

void AidlPowerHalWrapper::closePowerHintSession() {
    if (mPowerHintSession != nullptr) {
        mPowerHintSession->close();
        mPowerHintSession = nullptr;
    }
}

void AidlPowerHalWrapper::restartPowerHintSession() {
    closePowerHintSession();
    startPowerHintSession();
}

void AidlPowerHalWrapper::setPowerHintSessionThreadIds(const std::vector<int32_t>& threadIds) {
    if (threadIds != mPowerHintThreadIds) {
        mPowerHintThreadIds = threadIds;
        if (isPowerHintSessionRunning()) {
            restartPowerHintSession();
        }
    }
}

bool AidlPowerHalWrapper::startPowerHintSession() {
    if (mPowerHintSession != nullptr || mPowerHintThreadIds.empty()) {
        ALOGV("Cannot start power hint session, skipping");
        return false;
    }
    auto ret =
            mPowerHal->createHintSession(getpid(), static_cast<int32_t>(getuid()),
                                         mPowerHintThreadIds, mTargetDuration, &mPowerHintSession);
    if (!ret.isOk()) {
        ALOGW("Failed to start power hint session with error: %s",
              ret.exceptionToString(ret.exceptionCode()).c_str());
    } else {
        mLastTargetDurationSent = mTargetDuration;
    }
    return isPowerHintSessionRunning();
}

bool AidlPowerHalWrapper::shouldSetTargetDuration(int64_t targetDurationNanos) {
    if (targetDurationNanos <= 0) {
        return false;
    }
    // report if the change in target from our last submission to now exceeds the threshold
    return abs(1.0 -
               static_cast<double>(mLastTargetDurationSent) /
                       static_cast<double>(targetDurationNanos)) >= kAllowedTargetDeviationPercent;
}

void AidlPowerHalWrapper::setTargetWorkDuration(int64_t targetDurationNanos) {
    ATRACE_CALL();
    mTargetDuration = targetDurationNanos;
    if (sTraceHintSessionData) ATRACE_INT64("Time target", targetDurationNanos);
    if (!sNormalizeTarget && isPowerHintSessionRunning() &&
        shouldSetTargetDuration(targetDurationNanos)) {
        if (mLastActualDurationSent.has_value()) {
            // update the error term here since we are actually sending an update to powerhal
            if (sTraceHintSessionData)
                ATRACE_INT64("Target error term", targetDurationNanos - *mLastActualDurationSent);
        }
        ALOGV("Sending target time: %" PRId64 "ns", targetDurationNanos);
        mLastTargetDurationSent = targetDurationNanos;
        auto ret = mPowerHintSession->updateTargetWorkDuration(targetDurationNanos);
        if (!ret.isOk()) {
            ALOGW("Failed to set power hint target work duration with error: %s",
                  ret.exceptionMessage().c_str());
            mShouldReconnectHal = true;
        }
    }
}

bool AidlPowerHalWrapper::shouldReportActualDurationsNow() {
    // report if we have never reported before or are approaching a stale session
    if (!mLastActualDurationSent.has_value() ||
        (systemTime() - mLastActualReportTimestamp) > kStaleTimeout.count()) {
        return true;
    }

    if (!mActualDuration.has_value()) {
        return false;
    }

    // duration of most recent timing
    const double mostRecentActualDuration = static_cast<double>(*mActualDuration);
    // duration of the last timing actually reported to the powerhal
    const double lastReportedActualDuration = static_cast<double>(*mLastActualDurationSent);

    // report if the change in duration from then to now exceeds the threshold
    return abs(1.0 - mostRecentActualDuration / lastReportedActualDuration) >=
            kAllowedActualDeviationPercent;
}

void AidlPowerHalWrapper::sendActualWorkDuration(int64_t actualDurationNanos,
                                                 nsecs_t timeStampNanos) {
    ATRACE_CALL();

    if (actualDurationNanos < 0 || !isPowerHintSessionRunning()) {
        ALOGV("Failed to send actual work duration, skipping");
        return;
    }
    nsecs_t reportedDuration = actualDurationNanos;

    // normalize the sent values to a pre-set target
    if (sNormalizeTarget) {
        reportedDuration += mLastTargetDurationSent - mTargetDuration;
    } else {
        // when target duration change is within deviation and not updated, adjust the actual
        // duration proportionally based on the difference, e.g. if new target is 5ms longer than
        // last reported but actual duration is the same as last target, we want to report a smaller
        // actual work duration now to indicate that we are overshooting
        if (mLastTargetDurationSent != kDefaultTarget.count() && mTargetDuration != 0) {
            reportedDuration =
                    static_cast<int64_t>(static_cast<long double>(mLastTargetDurationSent) /
                                         mTargetDuration * actualDurationNanos);
            mActualDuration = reportedDuration;
        }
    }
    mActualDuration = reportedDuration;
    WorkDuration duration;
    duration.durationNanos = reportedDuration;
    duration.timeStampNanos = timeStampNanos;
    mPowerHintQueue.push_back(duration);

    if (sTraceHintSessionData) {
        ATRACE_INT64("Measured duration", actualDurationNanos);
        ATRACE_INT64("Target error term", mTargetDuration - actualDurationNanos);

        ATRACE_INT64("Reported duration", reportedDuration);
        ATRACE_INT64("Reported target", mLastTargetDurationSent);
        ATRACE_INT64("Reported target error term", mLastTargetDurationSent - reportedDuration);
    }

    ALOGV("Sending actual work duration of: %" PRId64 " on reported target: %" PRId64
          " with error: %" PRId64,
          reportedDuration, mLastTargetDurationSent, mLastTargetDurationSent - reportedDuration);

    // This rate limiter queues similar duration reports to the powerhal into
    // batches to avoid excessive binder calls. The criteria to send a given batch
    // are outlined in shouldReportActualDurationsNow()
    if (shouldReportActualDurationsNow()) {
        ALOGV("Sending hint update batch");
        mLastActualReportTimestamp = systemTime();
        auto ret = mPowerHintSession->reportActualWorkDuration(mPowerHintQueue);
        if (!ret.isOk()) {
            ALOGW("Failed to report actual work durations with error: %s",
                  ret.exceptionMessage().c_str());
            mShouldReconnectHal = true;
        }
        mPowerHintQueue.clear();
        // we save the non-normalized value here to detect % changes
        mLastActualDurationSent = reportedDuration;
    }
}

bool AidlPowerHalWrapper::shouldReconnectHAL() {
    return mShouldReconnectHal;
}

std::vector<int32_t> AidlPowerHalWrapper::getPowerHintSessionThreadIds() {
    return mPowerHintThreadIds;
}

std::optional<int64_t> AidlPowerHalWrapper::getTargetWorkDuration() {
    return mTargetDuration;
}

const bool AidlPowerHalWrapper::sTraceHintSessionData =
        base::GetBoolProperty(std::string("debug.sf.trace_hint_sessions"), false);

const bool AidlPowerHalWrapper::sNormalizeTarget =
        base::GetBoolProperty(std::string("debug.sf.normalize_hint_session_durations"), false);

PowerAdvisor::HalWrapper* PowerAdvisor::getPowerHal() {
    static std::unique_ptr<HalWrapper> sHalWrapper = nullptr;
    static bool sHasHal = true;

    if (!sHasHal) {
        return nullptr;
    }

    // grab old hint session values before we destroy any existing wrapper
    std::vector<int32_t> oldPowerHintSessionThreadIds;
    std::optional<int64_t> oldTargetWorkDuration;

    if (sHalWrapper != nullptr) {
        oldPowerHintSessionThreadIds = sHalWrapper->getPowerHintSessionThreadIds();
        oldTargetWorkDuration = sHalWrapper->getTargetWorkDuration();
    }

    // If we used to have a HAL, but it stopped responding, attempt to reconnect
    if (mReconnectPowerHal) {
        sHalWrapper = nullptr;
        mReconnectPowerHal = false;
    }

    if (sHalWrapper != nullptr) {
        auto wrapper = sHalWrapper.get();
        // if the wrapper is fine, return it, but if it indicates a reconnect, remake it
        if (!wrapper->shouldReconnectHAL()) {
            return wrapper;
        }
        ALOGD("Reconnecting Power HAL");
        sHalWrapper = nullptr;
    }

    // at this point, we know for sure there is no running session
    mPowerHintSessionRunning = false;

    // First attempt to connect to the AIDL Power HAL
    sHalWrapper = AidlPowerHalWrapper::connect();

    // If that didn't succeed, attempt to connect to the HIDL Power HAL
    if (sHalWrapper == nullptr) {
        sHalWrapper = HidlPowerHalWrapper::connect();
    } else {
        ALOGD("Successfully connecting AIDL Power HAL");
        // if AIDL, pass on any existing hint session values
        // thread ids always safe to set
        sHalWrapper->setPowerHintSessionThreadIds(oldPowerHintSessionThreadIds);
        // only set duration and start if duration is defined
        if (oldTargetWorkDuration.has_value()) {
            sHalWrapper->setTargetWorkDuration(*oldTargetWorkDuration);
            // only start if possible to run and both threadids and duration are defined
            if (usePowerHintSession() && !oldPowerHintSessionThreadIds.empty()) {
                mPowerHintSessionRunning = sHalWrapper->startPowerHintSession();
            }
        }
    }

    // If we make it to this point and still don't have a HAL, it's unlikely we
    // will, so stop trying
    if (sHalWrapper == nullptr) {
        sHasHal = false;
    }

    return sHalWrapper.get();
}

} // namespace impl
} // namespace Hwc2
} // namespace android