[libcamera-devel] [PATCH v4 2/6] libcamera: v4l2_device: List controls at device open

[Jacopo Mondi]

Enumerate all the controls a device supports at open() time.
Store the control informations in a map inside the device to save
querying the control when setting or getting its value from the device.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/include/v4l2_device.h |  8 +++++++-
 src/libcamera/v4l2_device.cpp       | 30 +++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
index 2c26f3eae2b4..563be151c257 100644
--- a/src/libcamera/include/v4l2_device.h
+++ b/src/libcamera/include/v4l2_device.h
@@ -7,12 +7,15 @@
 #ifndef __LIBCAMERA_V4L2_DEVICE_H__
 #define __LIBCAMERA_V4L2_DEVICE_H__
 
+#include <map>
 #include <string>
 
 #include "log.h"
 
 namespace libcamera {
 
+class V4L2ControlInfo;
+
 class V4L2Device : protected Loggable
 {
 public:
@@ -22,7 +25,7 @@ public:
 
 protected:
 	V4L2Device(const std::string &deviceNode, const std::string &logTag);
-	~V4L2Device() {}
+	~V4L2Device();
 
 	int fd() { return fd_; }
 
@@ -33,6 +36,9 @@ protected:
 	std::string logPrefix() const { return "'" + logTag_ + "'"; }
 
 private:
+	void listControls();
+
+	std::map<unsigned int, V4L2ControlInfo *> controls_;
 	std::string deviceNode_;
 	std::string logTag_;
 	int fd_;
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index eeed0a70fb0e..58dd94836686 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -13,6 +13,7 @@
 #include <unistd.h>
 
 #include "log.h"
+#include "v4l2_controls.h"
 
 /**
  * \file v4l2_device.h
@@ -82,6 +83,12 @@ V4L2Device::V4L2Device(const std::string &deviceNode, const std::string &logTag)
 {
 }
 
+V4L2Device::~V4L2Device()
+{
+	for (auto &pair : controls_)
+		delete pair.second;
+}
+
 /**
  * \fn V4L2Device::fd()
  * \brief Retrieve the V4L2 device file descriptor
@@ -114,6 +121,8 @@ int V4L2Device::open(unsigned int flags)
 
 	fd_ = ret;
 
+	listControls();
+
 	return 0;
 }
 
@@ -141,4 +150,25 @@ int V4L2Device::ioctl(unsigned long request, void *argp)
  * \return The tag to prefix log messages with
  */
 
+/*
+ * \brief List and store all controls supported by the V4L2 device
+ */
+void V4L2Device::listControls()
+{
+	struct v4l2_query_ext_ctrl ctrl = {};
+
+	/* \todo: add support for menu and compound controls. */
+	ctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
+	while (ioctl(VIDIOC_QUERY_EXT_CTRL, &ctrl) == 0) {
+		if (ctrl.type == V4L2_CTRL_TYPE_CTRL_CLASS ||
+		    ctrl.flags & V4L2_CTRL_FLAG_DISABLED) {
+			ctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
+			continue;
+		}
+
+		controls_[ctrl.id] = new V4L2ControlInfo(ctrl);
+		ctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
+	}
+}
+
 } /* namespace libcamera */
-- 
2.21.0