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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #define LOG_TAG "DisplayEventDispatcher"
     18 
     19 #include <cinttypes>
     20 #include <cstdint>
     21 
     22 #include <androidfw/DisplayEventDispatcher.h>
     23 #include <gui/DisplayEventReceiver.h>
     24 #include <utils/Log.h>
     25 #include <utils/Looper.h>
     26 
     27 #include <utils/Timers.h>
     28 
     29 namespace android {
     30 
     31 // Number of events to read at a time from the DisplayEventDispatcher pipe.
     32 // The value should be large enough that we can quickly drain the pipe
     33 // using just a few large reads.
     34 static const size_t EVENT_BUFFER_SIZE = 100;
     35 
     36 DisplayEventDispatcher::DisplayEventDispatcher(const sp<Looper>& looper) :
     37         mLooper(looper), mWaitingForVsync(false) {
     38     ALOGV("dispatcher %p ~ Initializing display event dispatcher.", this);
     39 }
     40 
     41 status_t DisplayEventDispatcher::initialize() {
     42     status_t result = mReceiver.initCheck();
     43     if (result) {
     44         ALOGW("Failed to initialize display event receiver, status=%d", result);
     45         return result;
     46     }
     47 
     48     int rc = mLooper->addFd(mReceiver.getFd(), 0, Looper::EVENT_INPUT,
     49             this, NULL);
     50     if (rc < 0) {
     51         return UNKNOWN_ERROR;
     52     }
     53     return OK;
     54 }
     55 
     56 void DisplayEventDispatcher::dispose() {
     57     ALOGV("dispatcher %p ~ Disposing display event dispatcher.", this);
     58 
     59     if (!mReceiver.initCheck()) {
     60         mLooper->removeFd(mReceiver.getFd());
     61     }
     62 }
     63 
     64 status_t DisplayEventDispatcher::scheduleVsync() {
     65     if (!mWaitingForVsync) {
     66         ALOGV("dispatcher %p ~ Scheduling vsync.", this);
     67 
     68         // Drain all pending events.
     69         nsecs_t vsyncTimestamp;
     70         int32_t vsyncDisplayId;
     71         uint32_t vsyncCount;
     72         if (processPendingEvents(&vsyncTimestamp, &vsyncDisplayId, &vsyncCount)) {
     73             ALOGE("dispatcher %p ~ last event processed while scheduling was for %" PRId64 "",
     74                     this, ns2ms(static_cast<nsecs_t>(vsyncTimestamp)));
     75         }
     76 
     77         status_t status = mReceiver.requestNextVsync();
     78         if (status) {
     79             ALOGW("Failed to request next vsync, status=%d", status);
     80             return status;
     81         }
     82 
     83         mWaitingForVsync = true;
     84     }
     85     return OK;
     86 }
     87 
     88 int DisplayEventDispatcher::handleEvent(int, int events, void*) {
     89     if (events & (Looper::EVENT_ERROR | Looper::EVENT_HANGUP)) {
     90         ALOGE("Display event receiver pipe was closed or an error occurred.  "
     91                 "events=0x%x", events);
     92         return 0; // remove the callback
     93     }
     94 
     95     if (!(events & Looper::EVENT_INPUT)) {
     96         ALOGW("Received spurious callback for unhandled poll event.  "
     97                 "events=0x%x", events);
     98         return 1; // keep the callback
     99     }
    100 
    101     // Drain all pending events, keep the last vsync.
    102     nsecs_t vsyncTimestamp;
    103     int32_t vsyncDisplayId;
    104     uint32_t vsyncCount;
    105     if (processPendingEvents(&vsyncTimestamp, &vsyncDisplayId, &vsyncCount)) {
    106         ALOGV("dispatcher %p ~ Vsync pulse: timestamp=%" PRId64 ", id=%d, count=%d",
    107                 this, ns2ms(vsyncTimestamp), vsyncDisplayId, vsyncCount);
    108         mWaitingForVsync = false;
    109         dispatchVsync(vsyncTimestamp, vsyncDisplayId, vsyncCount);
    110     }
    111 
    112     return 1; // keep the callback
    113 }
    114 
    115 bool DisplayEventDispatcher::processPendingEvents(
    116         nsecs_t* outTimestamp, int32_t* outId, uint32_t* outCount) {
    117     bool gotVsync = false;
    118     DisplayEventReceiver::Event buf[EVENT_BUFFER_SIZE];
    119     ssize_t n;
    120     while ((n = mReceiver.getEvents(buf, EVENT_BUFFER_SIZE)) > 0) {
    121         ALOGV("dispatcher %p ~ Read %d events.", this, int(n));
    122         for (ssize_t i = 0; i < n; i++) {
    123             const DisplayEventReceiver::Event& ev = buf[i];
    124             switch (ev.header.type) {
    125             case DisplayEventReceiver::DISPLAY_EVENT_VSYNC:
    126                 // Later vsync events will just overwrite the info from earlier
    127                 // ones. That's fine, we only care about the most recent.
    128                 gotVsync = true;
    129                 *outTimestamp = ev.header.timestamp;
    130                 *outId = ev.header.id;
    131                 *outCount = ev.vsync.count;
    132                 break;
    133             case DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG:
    134                 dispatchHotplug(ev.header.timestamp, ev.header.id, ev.hotplug.connected);
    135                 break;
    136             default:
    137                 ALOGW("dispatcher %p ~ ignoring unknown event type %#x", this, ev.header.type);
    138                 break;
    139             }
    140         }
    141     }
    142     if (n < 0) {
    143         ALOGW("Failed to get events from display event dispatcher, status=%d", status_t(n));
    144     }
    145     return gotVsync;
    146 }
    147 }
    148