services/surfaceflinger/Scheduler/RefreshRateConfigs.h

/*
 * Copyright 2019 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.
 */

#pragma once

#include <algorithm>
#include <numeric>

#include "android-base/stringprintf.h"

#include "DisplayHardware/HWComposer.h"
#include "Scheduler/SchedulerUtils.h"

namespace android {
namespace scheduler {

/**
 * This class is used to encapsulate configuration for refresh rates. It holds infomation
 * about available refresh rates on the device, and the mapping between the numbers and human
 * readable names.
 */
class RefreshRateConfigs {
public:
    // Enum to indicate which vsync rate to run at. Power saving is intended to be the lowest
    // (eg. when the screen is in AOD mode or off), default is the old 60Hz, and performance
    // is the new 90Hz. Eventually we want to have a way for vendors to map these in the configs.
    enum class RefreshRateType { POWER_SAVING, DEFAULT, PERFORMANCE };

    struct RefreshRate {
        // Type of the refresh rate.
        RefreshRateType type;
        // This config ID corresponds to the position of the config in the vector that is stored
        // on the device.
        int configId;
        // Human readable name of the refresh rate.
        std::string name;
    };

    // TODO(b/122916473): Get this information from configs prepared by vendors, instead of
    // baking them in.
    explicit RefreshRateConfigs(
            const std::vector<std::shared_ptr<const HWC2::Display::Config>>& configs) {
        init(configs);
    }
    ~RefreshRateConfigs() = default;

    const std::vector<RefreshRate>& getRefreshRates() { return mRefreshRates; }

private:
    void init(const std::vector<std::shared_ptr<const HWC2::Display::Config>>& configs) {
        // This is the rate that HWC encapsulates right now when the device is in DOZE mode.
        mRefreshRates.push_back(
                RefreshRate{RefreshRateType::POWER_SAVING, SCREEN_OFF_CONFIG_ID, "ScreenOff"});

        if (configs.size() < 1) {
            ALOGE("Device does not have valid configs. Config size is 0.");
            return;
        }

        // Create a map between config index and vsync period. This is all the info we need
        // from the configs.
        std::vector<std::pair<int, nsecs_t>> configIdToVsyncPeriod;
        for (int i = 0; i < configs.size(); ++i) {
            configIdToVsyncPeriod.emplace_back(i, configs.at(i)->getVsyncPeriod());
        }

        std::sort(configIdToVsyncPeriod.begin(), configIdToVsyncPeriod.end(),
                  [](const std::pair<int, nsecs_t>& a, const std::pair<int, nsecs_t>& b) {
                      return a.second > b.second;
                  });

        // When the configs are ordered by the resync rate. We assume that the first one is DEFAULT.
        nsecs_t vsyncPeriod = configIdToVsyncPeriod[0].second;
        if (vsyncPeriod != 0) {
            const float fps = 1e9 / vsyncPeriod;
            mRefreshRates.push_back(RefreshRate{RefreshRateType::DEFAULT,
                                                configIdToVsyncPeriod[0].first,
                                                base::StringPrintf("%2.ffps", fps)});
        }
        if (configs.size() < 2) {
            return;
        }

        // When the configs are ordered by the resync rate. We assume that the second one is
        // PERFORMANCE, eg. the higher rate.
        vsyncPeriod = configIdToVsyncPeriod[1].second;
        if (vsyncPeriod != 0) {
            const float fps = 1e9 / vsyncPeriod;
            mRefreshRates.push_back(RefreshRate{RefreshRateType::PERFORMANCE,
                                                configIdToVsyncPeriod[1].first,
                                                base::StringPrintf("%2.ffps", fps)});
        }
    }

    std::vector<RefreshRate> mRefreshRates;
};

} // namespace scheduler
} // namespace android