[v3,2/4] libcamera: device_enumerator: Support regex to match entity names
diff mbox series

Message ID 20251203-rzv2h-pre-v3-2-1493e0638626@ideasonboard.com
State New
Headers show
Series
  • Use regular expressions for entity name matching
Related show

Commit Message

Jacopo Mondi Dec. 3, 2025, 9:14 a.m. UTC 
From: Daniel Scally <dan.scally@ideasonboard.com>

Some entities in a media graph have names that might differ from
implementation to implementation; for example the Camera Receiver
Unit and CSI-2 receiver on the RZ/V2H(P) SoC have entities with names
that include their address, in the form "csi-16000400.csi2". Passing
that entity name to DeviceMatch is too inflexible given it would only
work if that specific CSI-2 receiver were the one being used.

Add an overload for DeviceMatch::add() such that users can pass in a
std::regex instead of a string. Update DeviceMatch::match() to check
for entities that are matched by the regular expressions added with
the new overload after checking for any exact matches from the vector
of strings. This allows us to use regex to match on patterns like
"csi-[0-9a-f]{8}.csi2".

Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

---
Changes in v3:
- As suggested by Barnabas accept an std::regex in add() instead of a
  reference and move it into the entityRegexs_ vector

- Exit early in DeviceMatch::match()

	for (const MediaEntity *entity : device->entities()) {
		if (!std::regex_search(entity->name(), nameRegex))
			continue;

		if (found) {

		}
	}

  Compared to

	for (const MediaEntity *entity : device->entities()) {
		if (std::regex_search(entity->name(), nameRegex)) {
			if (found) {

			}
		}
	}

- Invert the error logic when deviceNode is empty

	if (entity->deviceNode().empty()) {
		LOG(DeviceEnumerator, Debug)
			<< "Skip " << entity->name()
			<< ": no device node";
		continue;
	}

	found = true;

  Compared to

	if (!entity->deviceNode().empty()) {
		found = true;
	} else {
		 LOG(DeviceEnumerator, Debug)
			<< "Skip " << entity->name()
			<< ": no device node";
	}

Changes in v2:

    - Instead of replacing the existing ::add() function and
      matching process with regex, add an overload for ::add()
      that takes a regex and incorporate that into ::match()
      alongside the existing functionality.
---
 include/libcamera/internal/device_enumerator.h |  3 ++
 src/libcamera/device_enumerator.cpp            | 39 +++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

Patch
diff mbox series 

diff --git a/include/libcamera/internal/device_enumerator.h b/include/libcamera/internal/device_enumerator.h
index db3532a9887af913ceee20cbba3f945e56e7b61d..fa8806b0c2a47ab89fdc74fe01ef77bf2e68abb1 100644
--- a/include/libcamera/internal/device_enumerator.h
+++ b/include/libcamera/internal/device_enumerator.h
@@ -11,6 +11,7 @@ 
 #include <string>
 #include <vector>
 
+#include <libcamera/base/regex.h>
 #include <libcamera/base/signal.h>
 
 namespace libcamera {
@@ -23,12 +24,14 @@  public:
 	DeviceMatch(const std::string &driver);
 
 	void add(const std::string &entity);
+	void add(const std::regex entity);
 
 	bool match(const MediaDevice *device) const;
 
 private:
 	std::string driver_;
 	std::vector<std::string> entities_;
+	std::vector<std::regex> entityRegexs_;
 };
 
 class DeviceEnumerator
diff --git a/src/libcamera/device_enumerator.cpp b/src/libcamera/device_enumerator.cpp
index ae17862f676310ef568e5331106ed661e84b5130..2911d5f0385f9765a2eafce2085d1fd627d94b95 100644
--- a/src/libcamera/device_enumerator.cpp
+++ b/src/libcamera/device_enumerator.cpp
@@ -53,7 +53,8 @@  LOG_DEFINE_CATEGORY(DeviceEnumerator)
  *
  * A DeviceMatch is created with a specific Linux device driver in mind,
  * therefore the name of the driver is a required property. One or more Entity
- * names can be added as match criteria.
+ * names (or regular expressions designed to match an entity name) can be added
+ * as match criteria.
  *
  * Pipeline handlers are recommended to add entities to DeviceMatch as
  * appropriate to ensure that the media device they need can be uniquely
@@ -81,6 +82,15 @@  void DeviceMatch::add(const std::string &entity)
 	entities_.push_back(entity);
 }
 
+/**
+ * \brief Add a regex to match a media entity name to the search pattern
+ * \param[in] entity The regex intended to match to an entity in the media graph
+ */
+void DeviceMatch::add(const std::regex entity)
+{
+	entityRegexs_.push_back(std::move(entity));
+}
+
 /**
  * \brief Compare a search pattern with a media device
  * \param[in] device The media device
@@ -116,6 +126,33 @@  bool DeviceMatch::match(const MediaDevice *device) const
 			return false;
 	}
 
+	for (const std::regex &nameRegex : entityRegexs_) {
+		bool found = false;
+
+		for (const MediaEntity *entity : device->entities()) {
+			if (!std::regex_search(entity->name(), nameRegex))
+				continue;
+
+			if (found) {
+				LOG(DeviceEnumerator, Error)
+					<< "Multiple entities match regex";
+				return false;
+			}
+
+			if (entity->deviceNode().empty()) {
+				LOG(DeviceEnumerator, Debug)
+					<< "Skip " << entity->name()
+					<< ": no device node";
+				continue;
+			}
+
+			found = true;
+		}
+
+		if (!found)
+			return false;
+	}
+
 	return true;
 }