[libcamera-devel] [PATCH v2 1/2] libcamera: controls: Add read-only flag to ControlInfo

[Naushir Patuck]

Add a read-only flag to the ControlInfo flag to indicate whether a V4L2 control
is read-only or not. This flag only makes sense for V2L2 controls at preset, so
only update the ControlInfo constructor signature used by the V4L2Device class
to set the value of the flag.

Add a ControlInfo::readOnly() member function to retrive this flag.

Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
---
 include/libcamera/controls.h  |  5 ++++-
 src/libcamera/controls.cpp    | 17 +++++++++++++----
 src/libcamera/v4l2_device.cpp | 12 ++++++++----
 3 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
index cf94205577a5..488663a7ba04 100644
--- a/include/libcamera/controls.h
+++ b/include/libcamera/controls.h
@@ -270,7 +270,8 @@ class ControlInfo
 public:
 	explicit ControlInfo(const ControlValue &min = {},
 			     const ControlValue &max = {},
-			     const ControlValue &def = {});
+			     const ControlValue &def = {},
+			     bool readOnly = false);
 	explicit ControlInfo(Span<const ControlValue> values,
 			     const ControlValue &def = {});
 	explicit ControlInfo(std::set<bool> values, bool def);
@@ -279,6 +280,7 @@ public:
 	const ControlValue &min() const { return min_; }
 	const ControlValue &max() const { return max_; }
 	const ControlValue &def() const { return def_; }
+	bool readOnly() const { return readOnly_; }
 	const std::vector<ControlValue> &values() const { return values_; }
 
 	std::string toString() const;
@@ -297,6 +299,7 @@ private:
 	ControlValue min_;
 	ControlValue max_;
 	ControlValue def_;
+	bool readOnly_;
 	std::vector<ControlValue> values_;
 };
 
diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
index 6dbf9b348709..fc66abad600d 100644
--- a/src/libcamera/controls.cpp
+++ b/src/libcamera/controls.cpp
@@ -484,11 +484,13 @@ void ControlValue::reserve(ControlType type, bool isArray, std::size_t numElemen
  * \param[in] min The control minimum value
  * \param[in] max The control maximum value
  * \param[in] def The control default value
+ * \param[in] readOnly Read-only status of a V4L2 control
  */
 ControlInfo::ControlInfo(const ControlValue &min,
 			 const ControlValue &max,
-			 const ControlValue &def)
-	: min_(min), max_(max), def_(def)
+			 const ControlValue &def,
+			 bool readOnly)
+	: min_(min), max_(max), def_(def), readOnly_(readOnly)
 {
 }
 
@@ -525,7 +527,8 @@ ControlInfo::ControlInfo(Span<const ControlValue> values,
  * default value is \a def.
  */
 ControlInfo::ControlInfo(std::set<bool> values, bool def)
-	: min_(false), max_(true), def_(def), values_({ false, true })
+	: min_(false), max_(true), def_(def), readOnly_(false),
+	  values_({ false, true })
 {
 	ASSERT(values.count(def) && values.size() == 2);
 }
@@ -538,7 +541,7 @@ ControlInfo::ControlInfo(std::set<bool> values, bool def)
  * value. The minimum, maximum, and default values will all be \a value.
  */
 ControlInfo::ControlInfo(bool value)
-	: min_(value), max_(value), def_(value)
+	: min_(value), max_(value), def_(value), readOnly_(false)
 {
 	values_ = { value };
 }
@@ -571,6 +574,12 @@ ControlInfo::ControlInfo(bool value)
  * \return A ControlValue with the default value for the control
  */
 
+/**
+ * \fn ControlInfo::readOnly()
+ * \brief Identifies if a V4L2 control is flagged as read-only
+ * \return True if the V4L2 control is read-only, false otherwise
+ */
+
 /**
  * \fn ControlInfo::values()
  * \brief Retrieve the list of valid values
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index 57a88d96b12c..9018f1b0b9e1 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -535,17 +535,20 @@ std::optional<ControlInfo> V4L2Device::v4l2ControlInfo(const v4l2_query_ext_ctrl
 	case V4L2_CTRL_TYPE_U8:
 		return ControlInfo(static_cast<uint8_t>(ctrl.minimum),
 				   static_cast<uint8_t>(ctrl.maximum),
-				   static_cast<uint8_t>(ctrl.default_value));
+				   static_cast<uint8_t>(ctrl.default_value),
+				   !!(ctrl.flags & V4L2_CTRL_FLAG_READ_ONLY));
 
 	case V4L2_CTRL_TYPE_BOOLEAN:
 		return ControlInfo(static_cast<bool>(ctrl.minimum),
 				   static_cast<bool>(ctrl.maximum),
-				   static_cast<bool>(ctrl.default_value));
+				   static_cast<bool>(ctrl.default_value),
+				   !!(ctrl.flags & V4L2_CTRL_FLAG_READ_ONLY));
 
 	case V4L2_CTRL_TYPE_INTEGER64:
 		return ControlInfo(static_cast<int64_t>(ctrl.minimum),
 				   static_cast<int64_t>(ctrl.maximum),
-				   static_cast<int64_t>(ctrl.default_value));
+				   static_cast<int64_t>(ctrl.default_value),
+				   !!(ctrl.flags & V4L2_CTRL_FLAG_READ_ONLY));
 
 	case V4L2_CTRL_TYPE_INTEGER_MENU:
 	case V4L2_CTRL_TYPE_MENU:
@@ -554,7 +557,8 @@ std::optional<ControlInfo> V4L2Device::v4l2ControlInfo(const v4l2_query_ext_ctrl
 	default:
 		return ControlInfo(static_cast<int32_t>(ctrl.minimum),
 				   static_cast<int32_t>(ctrl.maximum),
-				   static_cast<int32_t>(ctrl.default_value));
+				   static_cast<int32_t>(ctrl.default_value),
+				   !!(ctrl.flags & V4L2_CTRL_FLAG_READ_ONLY));
 	}
 }
 
-- 
2.25.1