[libcamera-devel] [PATCH v2 3/6] libcamera: v4l2_device: Add support for META_CAPTURE devices

[Jacopo Mondi]

Add support for devices that provide video meta-data to v4l2_device.cpp
and re-arrange bufferType handling in open() method.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/include/v4l2_device.h |  4 +++
 src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
 2 files changed, 27 insertions(+), 15 deletions(-)

diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
index 1d31d1b403bc..52eb6785cc15 100644
--- a/src/libcamera/include/v4l2_device.h
+++ b/src/libcamera/include/v4l2_device.h
@@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
 		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
 					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
 	}
+	bool isMeta() const
+	{
+		return device_caps() & V4L2_CAP_META_CAPTURE;
+	}
 	bool isOutput() const
 	{
 		return device_caps() & (V4L2_CAP_VIDEO_OUTPUT |
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index 24e115554a99..8be8af7a2893 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -79,6 +79,15 @@ LOG_DEFINE_CATEGORY(V4L2)
  * \return True if the device can output video frames
  */
 
+/**
+ * \fn bool V4L2Capability::isMeta()
+ * \brief Identify if the device is capable of providing video meta-data
+ *
+ * FIXME: add support for META_OUTPUT, introduced in Linux v4.20
+ *
+ * \return True if the device can provide video meta-data
+ */
+
 /**
  * \fn bool V4L2Capability::hasStreaming()
  * \brief Determine if the device can perform Streaming I/O
@@ -280,33 +289,32 @@ int V4L2Device::open()
 		<< "Opened device " << caps_.bus_info() << ": "
 		<< caps_.driver() << ": " << caps_.card();
 
-	if (!caps_.isCapture() && !caps_.isOutput()) {
-		LOG(V4L2, Debug) << "Device is not a supported type";
-		return -EINVAL;
-	}
-
 	if (!caps_.hasStreaming()) {
 		LOG(V4L2, Error) << "Device does not support streaming I/O";
 		return -EINVAL;
 	}
 
-	if (caps_.isCapture())
+	/*
+	 * Set buffer type and wait for read notifications on CAPTURE devices
+	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
+	 */
+	if (caps_.isCapture()) {
+		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
 		bufferType_ = caps_.isMultiplanar()
 			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
 			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
-	else
+	} else if (caps_.isOutput()) {
+		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
 		bufferType_ = caps_.isMultiplanar()
 			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
 			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
-
-	/*
-	 *  We wait for Read notifications on CAPTURE devices (POLLIN), and
-	 *  Write notifications for OUTPUT devices (POLLOUT).
-	 */
-	if (caps_.isCapture())
+	} else if (caps_.isMeta()) {
 		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
-	else
-		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
+		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
+	} else {
+		LOG(V4L2, Debug) << "Device is not a supported type";
+		return -EINVAL;
+	}
 
 	fdEvent_->activated.connect(this, &V4L2Device::bufferAvailable);
 	fdEvent_->setEnabled(false);
-- 
2.20.1