[v1,06/33] libcamera: Add support for V4L2 requests

24505 diff mbox series

diff --git a/include/libcamera/internal/media_device.h b/include/libcamera/internal/media_device.h
index b3a48b98d64b..74cb9ba1542d 100644
--- a/include/libcamera/internal/media_device.h
+++ b/include/libcamera/internal/media_device.h
@@ -18,6 +18,7 @@ 
 #include <libcamera/base/unique_fd.h>
 
 #include "libcamera/internal/media_object.h"
+#include "libcamera/internal/v4l2_request.h"
 
 namespace libcamera {
 
@@ -57,6 +58,11 @@  public:
 
 	std::vector<MediaEntity *> locateEntities(unsigned int function);
 
+	int allocateRequests(unsigned int count,
+			     std::vector<std::unique_ptr<V4L2Request>> *requests);
+
+	bool supportsRequests();
+
 protected:
 	std::string logPrefix() const override;
 
@@ -87,6 +93,7 @@  private:
 	UniqueFD fd_;
 	bool valid_;
 	bool acquired_;
+	std::optional<bool> supportsRequests_;
 
 	std::map<unsigned int, MediaObject *> objects_;
 	std::vector<MediaEntity *> entities_;
diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build
index 45c299f6a332..e9540a2f734f 100644
--- a/include/libcamera/internal/meson.build
+++ b/include/libcamera/internal/meson.build
@@ -44,6 +44,7 @@  libcamera_internal_headers = files([
     'sysfs.h',
     'v4l2_device.h',
     'v4l2_pixelformat.h',
+    'v4l2_request.h',
     'v4l2_subdevice.h',
     'v4l2_videodevice.h',
     'vector.h',
diff --git a/include/libcamera/internal/v4l2_device.h b/include/libcamera/internal/v4l2_device.h
index 5bc9da96677d..dbbd118abd00 100644
--- a/include/libcamera/internal/v4l2_device.h
+++ b/include/libcamera/internal/v4l2_device.h
@@ -24,6 +24,7 @@ 
 #include <libcamera/controls.h>
 
 #include "libcamera/internal/formats.h"
+#include "libcamera/internal/v4l2_request.h"
 
 namespace libcamera {
 
@@ -37,8 +38,8 @@  public:
 
 	const ControlInfoMap &controls() const { return controls_; }
 
-	ControlList getControls(Span<const uint32_t> ids);
-	int setControls(ControlList *ctrls);
+	ControlList getControls(Span<const uint32_t> ids, const V4L2Request *request = nullptr);
+	int setControls(ControlList *ctrls, const V4L2Request *request = nullptr);
 
 	const struct v4l2_query_ext_ctrl *controlInfo(uint32_t id) const;
 
diff --git a/include/libcamera/internal/v4l2_request.h b/include/libcamera/internal/v4l2_request.h
new file mode 100644
index 000000000000..bf1bea3261af
--- /dev/null
+++ b/include/libcamera/internal/v4l2_request.h
@@ -0,0 +1,49 @@ 
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2025, Ideas On Board
+ *
+ * V4L2 requests
+ */
+
+#pragma once
+
+#include <string>
+
+#include <linux/videodev2.h>
+
+#include <libcamera/base/event_notifier.h>
+#include <libcamera/base/log.h>
+#include <libcamera/base/signal.h>
+#include <libcamera/base/span.h>
+#include <libcamera/base/unique_fd.h>
+
+#include <libcamera/color_space.h>
+#include <libcamera/controls.h>
+
+namespace libcamera {
+
+class V4L2Request : protected Loggable
+{
+public:
+	bool isValid() const { return fd_.isValid(); }
+	int fd() const { return fd_.get(); }
+
+	int reinit();
+	int queue();
+
+	V4L2Request(int fd = -1);
+	~V4L2Request() = default;
+
+	Signal<V4L2Request *> requestDone;
+
+private:
+	LIBCAMERA_DISABLE_COPY_AND_MOVE(V4L2Request)
+
+	void requestReady();
+	std::string logPrefix() const override;
+
+	UniqueFD fd_;
+	EventNotifier fdNotifier_;
+};
+
+} /* namespace libcamera */
diff --git a/include/libcamera/internal/v4l2_videodevice.h b/include/libcamera/internal/v4l2_videodevice.h
index 5a7dcfdda118..2d290971a0ee 100644
--- a/include/libcamera/internal/v4l2_videodevice.h
+++ b/include/libcamera/internal/v4l2_videodevice.h
@@ -33,6 +33,7 @@ 
 #include "libcamera/internal/formats.h"
 #include "libcamera/internal/v4l2_device.h"
 #include "libcamera/internal/v4l2_pixelformat.h"
+#include "libcamera/internal/v4l2_request.h"
 
 namespace libcamera {
 
@@ -217,7 +218,7 @@  public:
 	int importBuffers(unsigned int count);
 	int releaseBuffers();
 
-	int queueBuffer(FrameBuffer *buffer);
+	int queueBuffer(FrameBuffer *buffer, const V4L2Request *request = nullptr);
 	Signal<FrameBuffer *> bufferReady;
 
 	int streamOn();
diff --git a/src/libcamera/media_device.cpp b/src/libcamera/media_device.cpp
index 353f34a81eca..673c53fefdd7 100644
--- a/src/libcamera/media_device.cpp
+++ b/src/libcamera/media_device.cpp
@@ -20,6 +20,7 @@ 
 #include <linux/media.h>
 
 #include <libcamera/base/log.h>
+#include "libcamera/internal/v4l2_request.h"
 
 /**
  * \file media_device.h
@@ -851,4 +852,50 @@  std::vector<MediaEntity *> MediaDevice::locateEntities(unsigned int function)
 	return found;
 }
 
+/**
+ * \brief Allocate requests
+ * \param[in] count Number of requests to allocate
+ * \param[out] requests Vector to store allocated requests
+ *
+ * Allocates and stores \a count requests in \a requests. If allocation fails,
+ * and error is returned and \a requests is cleared.
+ *
+ * \return 0 on success or a negative error code otherwise
+ */
+int MediaDevice::allocateRequests(unsigned int count,
+				  std::vector<std::unique_ptr<V4L2Request>> *requests)
+{
+	requests->resize(count);
+	for (unsigned int i = 0; i < count; i++) {
+		int requestFd;
+		int ret = ::ioctl(fd_.get(), MEDIA_IOC_REQUEST_ALLOC, &requestFd);
+		if (ret < 0) {
+			requests->clear();
+			return -errno;
+		}
+		(*requests)[i] = std::make_unique<V4L2Request>(requestFd);
+	}
+
+	return 0;
+}
+
+/**
+ * \brief Check if requests are supported
+ *
+ * Checks if the device supports V4L2 requests by trying to allocate a single
+ * request. The result is cached, so the allocation is only tried once.
+ *
+ * \return True if the device supports requests, false otherwise
+ */
+bool MediaDevice::supportsRequests()
+{
+	if (supportsRequests_.has_value())
+		return supportsRequests_.value();
+
+	std::vector<std::unique_ptr<V4L2Request>> requests;
+	supportsRequests_ = (allocateRequests(1, &requests) == 0);
+
+	return supportsRequests_.value();
+}
+
 } /* namespace libcamera */
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index 5b9b86f211f1..34e20f557514 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -54,6 +54,7 @@  libcamera_internal_sources = files([
     'sysfs.cpp',
     'v4l2_device.cpp',
     'v4l2_pixelformat.cpp',
+    'v4l2_request.cpp',
     'v4l2_subdevice.cpp',
     'v4l2_videodevice.cpp',
     'vector.cpp',
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index 8c78b8c424e5..7a669a0303c1 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -162,6 +162,7 @@  void V4L2Device::close()
 /**
  * \brief Read controls from the device
  * \param[in] ids The list of controls to read, specified by their ID
+ * \param[in] request An optional request
  *
  * This function reads the value of all controls contained in \a ids, and
  * returns their values as a ControlList.
@@ -171,10 +172,12 @@  void V4L2Device::close()
  * during validation of the requested controls, no control is read and this
  * function returns an empty control list.
  *
+ * If \a request is specified the controls tied to that request are read.
+ *
  * \return The control values in a ControlList on success, or an empty list on
  * error
  */
-ControlList V4L2Device::getControls(Span<const uint32_t> ids)
+ControlList V4L2Device::getControls(Span<const uint32_t> ids, const V4L2Request *request)
 {
 	if (ids.empty())
 		return {};
@@ -242,10 +245,16 @@  ControlList V4L2Device::getControls(Span<const uint32_t> ids)
 	}
 
 	struct v4l2_ext_controls v4l2ExtCtrls = {};
-	v4l2ExtCtrls.which = V4L2_CTRL_WHICH_CUR_VAL;
 	v4l2ExtCtrls.controls = v4l2Ctrls.data();
 	v4l2ExtCtrls.count = v4l2Ctrls.size();
 
+	if (request) {
+		v4l2ExtCtrls.which = V4L2_CTRL_WHICH_REQUEST_VAL;
+		v4l2ExtCtrls.request_fd = request->fd();
+	} else {
+		v4l2ExtCtrls.which = V4L2_CTRL_WHICH_CUR_VAL;
+	}
+
 	int ret = ioctl(VIDIOC_G_EXT_CTRLS, &v4l2ExtCtrls);
 	if (ret) {
 		unsigned int errorIdx = v4l2ExtCtrls.error_idx;
@@ -273,6 +282,7 @@  ControlList V4L2Device::getControls(Span<const uint32_t> ids)
 /**
  * \brief Write controls to the device
  * \param[in] ctrls The list of controls to write
+ * \param[in] request And optional request
  *
  * This function writes the value of all controls contained in \a ctrls, and
  * stores the values actually applied to the device in the corresponding
@@ -288,11 +298,15 @@  ControlList V4L2Device::getControls(Span<const uint32_t> ids)
  * are written and their values are updated in \a ctrls, while all other
  * controls are not written and their values are not changed.
  *
+ * If \a request is set, the controls will be applied to that request. If the
+ * device doesn't support requests, -EACCESS will be returned. If \a request is
+ * invalid, -EINVAL will be returned.
+ *
  * \return 0 on success or an error code otherwise
  * \retval -EINVAL One of the control is not supported or not accessible
  * \retval i The index of the control that failed
  */
-int V4L2Device::setControls(ControlList *ctrls)
+int V4L2Device::setControls(ControlList *ctrls, const V4L2Request *request)
 {
 	if (ctrls->empty())
 		return 0;
@@ -377,10 +391,16 @@  int V4L2Device::setControls(ControlList *ctrls)
 	}
 
 	struct v4l2_ext_controls v4l2ExtCtrls = {};
-	v4l2ExtCtrls.which = V4L2_CTRL_WHICH_CUR_VAL;
 	v4l2ExtCtrls.controls = v4l2Ctrls.data();
 	v4l2ExtCtrls.count = v4l2Ctrls.size();
 
+	if (request) {
+		v4l2ExtCtrls.which = V4L2_CTRL_WHICH_REQUEST_VAL;
+		v4l2ExtCtrls.request_fd = request->fd();
+	} else {
+		v4l2ExtCtrls.which = V4L2_CTRL_WHICH_CUR_VAL;
+	}
+
 	int ret = ioctl(VIDIOC_S_EXT_CTRLS, &v4l2ExtCtrls);
 	if (ret) {
 		unsigned int errorIdx = v4l2ExtCtrls.error_idx;
diff --git a/src/libcamera/v4l2_request.cpp b/src/libcamera/v4l2_request.cpp
new file mode 100644
index 000000000000..47a397ac47be
--- /dev/null
+++ b/src/libcamera/v4l2_request.cpp
@@ -0,0 +1,107 @@ 
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2025, Ideas On Board
+ *
+ * V4L2 Request API
+ */
+
+#include "libcamera/internal/v4l2_request.h"
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include <linux/media.h>
+
+#include <libcamera/base/event_notifier.h>
+#include <libcamera/base/log.h>
+
+/**
+ * \file v4l2_request.h
+ * \brief V4L2 Request
+ */
+
+namespace libcamera {
+
+LOG_DECLARE_CATEGORY(V4L2)
+
+/**
+ * \class V4L2Request
+ * \brief V4L2Request object and API
+ *
+ * The V4L2Request class wraps a V4L2 request fd and provides some convenience
+ * functions to handle request.
+ *
+ * It is usually constructed by calling \a MediaDevice::allocateRequests().
+ *
+ * A request can then be passed to the V4L2Device::setControls(),
+ * V4L2Device::getControls() and V4L2VideoDevice::queueBuffer().
+ */
+
+/**
+ * \brief Construct a V4L2Request
+ * \param[in] fd The request fd
+ */
+V4L2Request::V4L2Request(int fd)
+	: fd_(fd), fdNotifier_(fd, EventNotifier::Exception)
+{
+	if (!fd_.isValid())
+		return;
+
+	fdNotifier_.activated.connect(this, &V4L2Request::requestReady);
+	fdNotifier_.setEnabled(false);
+}
+
+/**
+ * \brief Reinit the request
+ *
+ * Calls MEDIA_REQUEST_IOC_REINIT om the request fd.
+ *
+ * \return 0 on success or a negative error code otherwise
+ */
+int V4L2Request::reinit()
+{
+	fdNotifier_.setEnabled(false);
+
+	if (::ioctl(fd_.get(), MEDIA_REQUEST_IOC_REINIT) < 0)
+		return -errno;
+
+	return 0;
+}
+
+/**
+ * \brief Reinit the request
+ *
+ * Calls MEDIA_REQUEST_IOC_QUEUE om the request fd.
+ *
+ * \return 0 on success or a negative error code otherwise
+ */
+int V4L2Request::queue()
+{
+	if (::ioctl(fd_.get(), MEDIA_REQUEST_IOC_QUEUE) < 0)
+		return -errno;
+
+	fdNotifier_.setEnabled(true);
+
+	return 0;
+}
+
+std::string V4L2Request::logPrefix() const
+{
+	return "Request [" + std::to_string(fd()) + "]";
+}
+
+/**
+ * \brief Slot to handle request done events
+ *
+ * When this slot is called, the request is done and the requestDone will be
+ * emitted.
+ */
+void V4L2Request::requestReady()
+{
+	requestDone.emit(this);
+}
+
+} /* namespace libcamera */
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index bb57c1b76a5b..8ce739f4bc65 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -30,6 +30,7 @@ 
 #include "libcamera/internal/framebuffer.h"
 #include "libcamera/internal/media_device.h"
 #include "libcamera/internal/media_object.h"
+#include "libcamera/internal/v4l2_request.h"
 
 /**
  * \file v4l2_videodevice.h
@@ -1629,6 +1630,7 @@  int V4L2VideoDevice::releaseBuffers()
 /**
  * \brief Queue a buffer to the video device
  * \param[in] buffer The buffer to be queued
+ * \param[in] request An optional request
  *
  * For capture video devices the \a buffer will be filled with data by the
  * device. For output video devices the \a buffer shall contain valid data and
@@ -1641,9 +1643,11 @@  int V4L2VideoDevice::releaseBuffers()
  * Note that queueBuffer() will fail if the device is in the process of being
  * stopped from a streaming state through streamOff().
  *
+ * If \a request is specified, the buffer will be tied to that request.
+ *
  * \return 0 on success or a negative error code otherwise
  */
-int V4L2VideoDevice::queueBuffer(FrameBuffer *buffer)
+int V4L2VideoDevice::queueBuffer(FrameBuffer *buffer, const V4L2Request *request)
 {
 	struct v4l2_plane v4l2Planes[VIDEO_MAX_PLANES] = {};
 	struct v4l2_buffer buf = {};
@@ -1674,6 +1678,10 @@  int V4L2VideoDevice::queueBuffer(FrameBuffer *buffer)
 	buf.type = bufferType_;
 	buf.memory = memoryType_;
 	buf.field = V4L2_FIELD_NONE;
+	if (request) {
+		buf.flags = V4L2_BUF_FLAG_REQUEST_FD;
+		buf.request_fd = request->fd();
+	}
 
 	bool multiPlanar = V4L2_TYPE_IS_MULTIPLANAR(buf.type);
 	Span<const FrameBuffer::Plane> planes = buffer->planes();