libcamera: Always check return value of MediaDevice::acquire()

In preparation for adding more responsibility to MediaDevice::acquire()
remove unneeded calls to acquire() and release(), and make sure all
needed calls to acquire() are checked and acted on.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

test/media_device/media_device_link_test.cpp

@@ -51,7 +51,11 @@ class MediaDeviceLinkTest : public Test
 			return TestSkip;
 		}
 
-		dev_->acquire();
+		if (!dev_->acquire()) {
+			cerr << "Unable to acquire media device "
+			     << dev_->deviceNode() << endl;
+			return TestSkip;
+		}
 
 		if (dev_->open()) {
 			cerr << "Failed to open media device at "

test/v4l2_device/v4l2_device_test.cpp

@@ -46,8 +46,6 @@ int V4L2DeviceTest::init()
 	if (!media_)
 		return TestSkip;
 
-	media_->acquire();
-
 	MediaEntity *entity = media_->getEntityByName("vivid-000-vid-cap");
 	if (!entity)
 		return TestSkip;
@@ -61,8 +59,6 @@ int V4L2DeviceTest::init()
 
 void V4L2DeviceTest::cleanup()
 {
-	media_->release();
-
 	capture_->streamOff();
 	capture_->releaseBuffers();
 	capture_->close();

test/v4l2_subdevice/v4l2_subdevice_test.cpp

@@ -45,20 +45,16 @@ int V4L2SubdeviceTest::init()
 		return TestSkip;
 	}
 
-	media_->acquire();
-
 	int ret = media_->open();
 	if (ret) {
 		cerr << "Unable to open media device: " << media_->deviceNode()
 		     << ": " << strerror(ret) << endl;
-		media_->release();
 		return TestSkip;
 	}
 
 	MediaEntity *videoEntity = media_->getEntityByName("Scaler");
 	if (!videoEntity) {
 		cerr << "Unable to find media entity 'Scaler'" << endl;
-		media_->release();
 		return TestFail;
 	}
 
@@ -67,7 +63,6 @@ int V4L2SubdeviceTest::init()
 	if (ret) {
 		cerr << "Unable to open video subdevice "
 		     << scaler_->entity()->deviceNode() << endl;
-		media_->release();
 		return TestSkip;
 	}
 
@@ -76,7 +71,5 @@ int V4L2SubdeviceTest::init()
 
 void V4L2SubdeviceTest::cleanup()
 {
-	media_->release();
-
 	delete scaler_;
 }