再探RK3588 CEC关机流程

原创已于 2025-03-18 06:34:49 修改 · 1.8k 阅读

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于 2024-08-12 16:56:24 首次发布

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CEC Framework层关机流程细节

我司产品有三路HDMI IN端子，在HDMI1端子整机关机，DVD不会关机。但是HDMI2、HDMI3会正常关机。首先我们用逻辑分析仪，量了整机关机，HDMI CEC引脚的波形，发现没有CEC的波形。到这里，我首先怀疑是硬件问题, 因为我们的三路HDMI是通过HDMI swith芯片在SOC上面拓展出来的，硬件可能漏接了一路HDMI1。但是发现在HDMI1通道，CEC的其他功能是正常的，排出了硬件问题的可能，只能从软件出发，好好分析代码了。

三、解决思路

1.是否可能是硬件问题

HDMI1异常，HDMI2、HDMI3正常，说明硬件是正常的。DVD也是正常的

2.确认DVD是否收到关机信号

使用逻辑分析仪，量了整机关机，HDMI CEC引脚的波形，发现没有CEC的波形。说明DVD未收到关机指令

3.确认整机是否发送关机信号

综合前两个实验，我们已经确认是软件层面的问题了。只能通过阅读Android系统源码来确认问题

四、代码流程分析

1.关机流程回顾

我们这里讲了，CEC的关机第一步是HdmiControlService监听到关机广播后，进行关机, 如下

    private class HdmiControlBroadcastReceiver extends BroadcastReceiver {
        @ServiceThreadOnly
        @Override
        public void onReceive(Context context, Intent intent) {
            assertRunOnServiceThread();
            boolean isReboot = SystemProperties.get(SHUTDOWN_ACTION_PROPERTY).contains("1");
            switch (intent.getAction()) {
                ···
                case Intent.ACTION_SHUTDOWN:
                    if (isPowerOnOrTransient() && !isReboot) {
                        onStandby(STANDBY_SHUTDOWN);
                    }
                    break;
            }
        }
    }

    @ServiceThreadOnly
    @VisibleForTesting
    protected void onStandby(final int standbyAction) {
        mWakeUpMessageReceived = false;
        assertRunOnServiceThread();
        mPowerStatusController.setPowerStatus(HdmiControlManager.POWER_STATUS_TRANSIENT_TO_STANDBY,
                false);
        invokeVendorCommandListenersOnControlStateChanged(false,
                HdmiControlManager.CONTROL_STATE_CHANGED_REASON_STANDBY);

        final List<HdmiCecLocalDevice> devices = getAllLocalDevices();

        if (!isStandbyMessageReceived() && !canGoToStandby()) {
            mPowerStatusController.setPowerStatus(HdmiControlManager.POWER_STATUS_STANDBY);
            for (HdmiCecLocalDevice device : devices) {
                device.onStandby(mStandbyMessageReceived, standbyAction);
            }
            return;
        }

        disableDevices(new PendingActionClearedCallback() {
            @Override
            public void onCleared(HdmiCecLocalDevice device) {
                Slog.v(TAG, "On standby-action cleared:" + device.mDeviceType);
                devices.remove(device);
                if (devices.isEmpty()) {
                    onPendingActionsCleared(standbyAction);
                    // We will not clear local devices here, since some OEM/SOC will keep passing
                    // the received packets until the application processor enters to the sleep
                    // actually.
                }
            }
        });
    }

前面一直想当然的以为调用关机的是在

            for (HdmiCecLocalDevice device : devices) {
                device.onStandby(mStandbyMessageReceived, standbyAction);
            }

但是实际调试过程中发现,if (!isStandbyMessageReceived() && !canGoToStandby())是未满足的, 最终的调用入口为

        disableDevices(new PendingActionClearedCallback() {
            @Override
            public void onCleared(HdmiCecLocalDevice device) {
                Slog.v(TAG, "On standby-action cleared:" + device.mDeviceType);
                devices.remove(device);
                if (devices.isEmpty()) {
                    onPendingActionsCleared(standbyAction);
                    // We will not clear local devices here, since some OEM/SOC will keep passing
                    // the received packets until the application processor enters to the sleep
                    // actually.
                }
            }
        });

在HDMI1通道下PendingActionClearedCallback的回调，是未被触发的, 其他通道正常触发。接着看触发回调之后的逻辑

    /**
     * Normally called after all devices have cleared their pending actions, to execute the final
     * phase of the standby flow.
     *
     * This can also be called during wakeup, when pending actions are cleared after failing to be
     * cleared during standby. In this case, it does not execute the standby flow.
     */
    @ServiceThreadOnly
    private void onPendingActionsCleared(int standbyAction) {
        assertRunOnServiceThread();
        Slog.v(TAG, "onPendingActionsCleared");

        if (mPowerStatusController.isPowerStatusTransientToStandby()) {
            mPowerStatusController.setPowerStatus(HdmiControlManager.POWER_STATUS_STANDBY);
            for (HdmiCecLocalDevice device : mHdmiCecNetwork.getLocalDeviceList()) {
            	//最终在这进行关机
                device.onStandby(mStandbyMessageReceived, standbyAction);
            }
            if (!isAudioSystemDevice()) {
                mCecController.setOption(OptionKey.SYSTEM_CEC_CONTROL, false);
                mMhlController.setOption(OPTION_MHL_SERVICE_CONTROL, DISABLED);
            }
        }

        // Always reset this flag to set up for the next standby
        mStandbyMessageReceived = false;
    }

最终在这里device.onStandby(mStandbyMessageReceived, standbyAction);进行关机流程。因此我们目标便是是要正常触发PendingActionClearedCallback回调函数，即可正常关机。我们先不纠结为什么条件未满足，我们先来看下，disableDevices这个函数需要如何触发回调函数

2.详细流程分析

首先我们来看disableDevices的实现, 他接受一个回调的参数PendingActionClearedCallback

    private void disableDevices(PendingActionClearedCallback callback)

PendingActionClearedCallback的实现如下，看注释是所有action清除的时候调用onCleared

    /**
     * A callback interface to get notified when all pending action is cleared. It can be called
     * when timeout happened.
     */
    interface PendingActionClearedCallback {
        void onCleared(HdmiCecLocalDevice device);
    }

接下来继续看disableDevices的实现,

    private void disableDevices(PendingActionClearedCallback callback) {
        if (mCecController != null) {
            for (HdmiCecLocalDevice device : mHdmiCecNetwork.getLocalDeviceList()) {
                device.disableDevice(mStandbyMessageReceived, callback);
            }
        }
        mMhlController.clearAllLocalDevices();
    }

遍历HdmiCecNetwork中的所有device，然后调用disableDevice

    /**
     * Disable device. {@code callback} is used to get notified when all pending actions are
     * completed or timeout is issued.
     *
     * @param initiatedByCec true if this sequence is initiated by the reception the CEC messages
     *     like &lt;Standby&gt;
     * @param originalCallback callback interface to get notified when all pending actions are
     *     cleared
     */
    protected void disableDevice(
            boolean initiatedByCec, final PendingActionClearedCallback originalCallback) {
        removeAction(AbsoluteVolumeAudioStatusAction.class);
        removeAction(SetAudioVolumeLevelDiscoveryAction.class);

        mPendingActionClearedCallback =
                new PendingActionClearedCallback() {
                    @Override
                    public void onCleared(HdmiCecLocalDevice device) {
                        mHandler.removeMessages(MSG_DISABLE_DEVICE_TIMEOUT);
                        originalCallback.onCleared(device);
                    }
                };
        mHandler.sendMessageDelayed(
                Message.obtain(mHandler, MSG_DISABLE_DEVICE_TIMEOUT), DEVICE_CLEANUP_TIMEOUT);
    }

从这里可以看到，如果想要触发disableDevices(PendingActionClearedCallback callback)中的回调函数，首先要出发mPendingActionClearedCallback, 然后调用 originalCallback.onCleared(device)才会触发最开始的回调函数。那么mPendingActionClearedCallback需要如何触发呢？

disableDevice函数体中removeAction的实现如下：

    @ServiceThreadOnly
    void removeAction(final HdmiCecFeatureAction action) {
        assertRunOnServiceThread();
        action.finish(false);
        mActions.remove(action);
        checkIfPendingActionsCleared();
    }

    protected void checkIfPendingActionsCleared() {
        if (mActions.isEmpty() && mPendingActionClearedCallback != null) {
            PendingActionClearedCallback callback = mPendingActionClearedCallback;
            // To prevent from calling the callback again during handling the callback itself.
            mPendingActionClearedCallback = null;
            callback.onCleared(this);
        }
    }

可以发现，在checkIfPendingActionsCleared中，只要if (mActions.isEmpty() && mPendingActionClearedCallback != null)条件满足，就会触发mPendingActionClearedCallback回调，

        mPendingActionClearedCallback =
                new PendingActionClearedCallback() {
                    @Override
                    public void onCleared(HdmiCecLocalDevice device) {
                        mHandler.removeMessages(MSG_DISABLE_DEVICE_TIMEOUT);
                        originalCallback.onCleared(device);
                    }
                };

然后在mPendingActionClearedCallback中, originalCallback.onCleared(device)中，触发HdmiControlService.java中disableDevices(new PendingActionClearedCallback() {处的回调,实现关机.

到这里，我们基本可以明确，因为mPendingActionClearedCallback在这个流程中一定不为null, 所有需要mActions.isEmpty为空是TV关机，DVD关机流程的关键.

然后在checkIfPendingActionsCleared中加了打印，果然在HDMI1通道下，mActions.isEmpty不为空，还存在一个Action
在这里插入图片描述
后面加打印确认在HDMI1通道下，关机的时候，还存在一个RoutingControlAction未被清除。

五、解决措施

既然确认是RoutingControlAction未被清除, 我们在中添加这一行removeAction(RoutingControlAction.class);代码，最终问题解决

    protected void disableDevice(
            boolean initiatedByCec, final PendingActionClearedCallback originalCallback) {
        removeAction(AbsoluteVolumeAudioStatusAction.class);
        removeAction(SetAudioVolumeLevelDiscoveryAction.class);
       	//在检测之前，移除RoutingControlAction，
        removeAction(RoutingControlAction.class);
        ···
    }