Camera: Load initial session params speculatively

In case camera clients don't pass any session parameters try to
load their initial values depending on the last cached default
request.

Bug: 79989121
Test: Camera CTS
Change-Id: I73dd6b37584f6ae5dc5b9681313eb080ddd53b88

services/camera/libcameraservice/device3/Camera3Device.cpp

@@ -77,7 +77,8 @@ Camera3Device::Camera3Device(const String8 &id):
         mNextShutterFrameNumber(0),
         mNextReprocessShutterFrameNumber(0),
         mListener(NULL),
-        mVendorTagId(CAMERA_METADATA_INVALID_VENDOR_ID)
+        mVendorTagId(CAMERA_METADATA_INVALID_VENDOR_ID),
+        mLastTemplateId(-1)
 {
     ATRACE_CALL();
     camera3_callback_ops::notify = &sNotify;
@@ -1597,6 +1598,18 @@ status_t Camera3Device::configureStreams(const CameraMetadata& sessionParams, in
     Mutex::Autolock il(mInterfaceLock);
     Mutex::Autolock l(mLock);
 
+    // In case the client doesn't include any session parameter, try a
+    // speculative configuration using the values from the last cached
+    // default request.
+    if (sessionParams.isEmpty() &&
+            ((mLastTemplateId > 0) && (mLastTemplateId < CAMERA3_TEMPLATE_COUNT)) &&
+            (!mRequestTemplateCache[mLastTemplateId].isEmpty())) {
+        ALOGV("%s: Speculative session param configuration with template id: %d", __func__,
+                mLastTemplateId);
+        return filterParamsAndConfigureLocked(mRequestTemplateCache[mLastTemplateId],
+                operatingMode);
+    }
+
     return filterParamsAndConfigureLocked(sessionParams, operatingMode);
 }
 
@@ -1673,6 +1686,7 @@ status_t Camera3Device::createDefaultRequest(int templateId,
 
         if (!mRequestTemplateCache[templateId].isEmpty()) {
             *request = mRequestTemplateCache[templateId];
+            mLastTemplateId = templateId;
             return OK;
         }
     }
@@ -1697,6 +1711,7 @@ status_t Camera3Device::createDefaultRequest(int templateId,
         mRequestTemplateCache[templateId].acquire(rawRequest);
 
         *request = mRequestTemplateCache[templateId];
+        mLastTemplateId = templateId;
     }
     return OK;
 }

services/camera/libcameraservice/device3/Camera3Device.h

@@ -1191,6 +1191,9 @@ class Camera3Device :
 
     metadata_vendor_id_t mVendorTagId;
 
+    // Cached last requested template id
+    int mLastTemplateId;
+
     /**
      * Static callback forwarding methods from HAL to instance
      */