From 6e2ba3f8c454f7fc2c2f8c3619ce818ad715c02e Mon Sep 17 00:00:00 2001
From: Emilian Peev <epeev@google.com>
Date: Thu, 25 Oct 2018 12:36:52 +0100
Subject: [PATCH] Camera: Avoid device sync during capture if possible

Currently we always sync using the latest request id
before standard capture. The purpose is to avoid
sending triggers and 3A mode settings out of sync to
Hal. However during regular capture the precapture
trigger is not always used so we should be able to
skip the device sync in this case. This can enable
capture requests to arrive in Hal with one preview
frame earlier.

Bug: 79682338
Test: Camera CTS
Change-Id: I9ea0b03968266d5c8f1e187358f13a21d394ff90
---
 .../libcameraservice/api1/Camera2Client.cpp   | 21 +++++++++++++++++--
 .../api1/client2/Parameters.cpp               |  1 +
 .../api1/client2/Parameters.h                 |  1 +
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/services/camera/libcameraservice/api1/Camera2Client.cpp b/services/camera/libcameraservice/api1/Camera2Client.cpp
index ab4971d929..c9c216b3ce 100644
--- a/services/camera/libcameraservice/api1/Camera2Client.cpp
+++ b/services/camera/libcameraservice/api1/Camera2Client.cpp
@@ -1446,6 +1446,7 @@ status_t Camera2Client::takePicture(int /*msgType*/) {
     if ( (res = checkPid(__FUNCTION__) ) != OK) return res;
 
     int takePictureCounter;
+    bool shouldSyncWithDevice = true;
     {
         SharedParameters::Lock l(mParameters);
         switch (l.mParameters.state) {
@@ -1531,12 +1532,23 @@ status_t Camera2Client::takePicture(int /*msgType*/) {
                     __FUNCTION__, mCameraId);
             mZslProcessor->clearZslQueue();
         }
+
+        // We should always sync with the device in case flash is turned on,
+        // the camera device suggests that flash is needed (AE state FLASH_REQUIRED)
+        // or we are in some other AE state different from CONVERGED that may need
+        // precapture trigger.
+        if (l.mParameters.flashMode != Parameters::FLASH_MODE_ON &&
+                (l.mParameters.aeState == ANDROID_CONTROL_AE_STATE_CONVERGED)) {
+            shouldSyncWithDevice  = false;
+        }
     }
 
     ATRACE_ASYNC_BEGIN(kTakepictureLabel, takePictureCounter);
 
-    // Need HAL to have correct settings before (possibly) triggering precapture
-    syncWithDevice();
+    // Make sure HAL has correct settings in case precapture trigger is needed.
+    if (shouldSyncWithDevice) {
+        syncWithDevice();
+    }
 
     res = mCaptureSequencer->startCapture();
     if (res != OK) {
@@ -1905,6 +1917,11 @@ void Camera2Client::notifyAutoFocus(uint8_t newState, int triggerId) {
 void Camera2Client::notifyAutoExposure(uint8_t newState, int triggerId) {
     ALOGV("%s: Autoexposure state now %d, last trigger %d",
             __FUNCTION__, newState, triggerId);
+    {
+        SharedParameters::Lock l(mParameters);
+        // Update state
+        l.mParameters.aeState = newState;
+    }
     mCaptureSequencer->notifyAutoExposure(newState, triggerId);
 }
 
diff --git a/services/camera/libcameraservice/api1/client2/Parameters.cpp b/services/camera/libcameraservice/api1/client2/Parameters.cpp
index 28d186abb4..7b1454d690 100644
--- a/services/camera/libcameraservice/api1/client2/Parameters.cpp
+++ b/services/camera/libcameraservice/api1/client2/Parameters.cpp
@@ -757,6 +757,7 @@ status_t Parameters::initialize(CameraDeviceBase *device, int deviceVersion) {
     focusState = ANDROID_CONTROL_AF_STATE_INACTIVE;
     shadowFocusMode = FOCUS_MODE_INVALID;
 
+    aeState = ANDROID_CONTROL_AE_STATE_INACTIVE;
     camera_metadata_ro_entry_t max3aRegions = staticInfo(ANDROID_CONTROL_MAX_REGIONS,
             Parameters::NUM_REGION, Parameters::NUM_REGION);
     if (max3aRegions.count != Parameters::NUM_REGION) return NO_INIT;
diff --git a/services/camera/libcameraservice/api1/client2/Parameters.h b/services/camera/libcameraservice/api1/client2/Parameters.h
index 42e7a47c82..e0086489cb 100644
--- a/services/camera/libcameraservice/api1/client2/Parameters.h
+++ b/services/camera/libcameraservice/api1/client2/Parameters.h
@@ -122,6 +122,7 @@ struct Parameters {
         int32_t high;
     };
 
+    uint8_t aeState; //latest AE state from Hal
     int32_t exposureCompensation;
     bool autoExposureLock;
     bool autoExposureLockAvailable;