[RFC,v1,03/20] libcamera: camera_sensor: Generate sensor IDs from a media entity
diff mbox series

Message ID 20260918080734.1228227-4-naush@raspberrypi.com
State New
Headers show
Series
  • libcamera: New enumeration API
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Commit Message

Naushir Patuck Sept. 18, 2026, 7:59 a.m. UTC 
Add a CameraSensorFactoryBase::generateId() helper that computes the
sensor ID from a MediaEntity using sysfs without opening the device.
Update CameraSensorLegacy and CameraSensorRaw to generate the sensor ID
with this new helper.

This change is in preparation for generating camera IDs at device
enumeration time.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
---
 include/libcamera/internal/camera_sensor.h    |  1 +
 src/libcamera/sensor/camera_sensor.cpp        | 27 +++++++++++++++++++
 src/libcamera/sensor/camera_sensor_legacy.cpp |  6 ++---
 src/libcamera/sensor/camera_sensor_raw.cpp    |  3 +--
 4 files changed, 32 insertions(+), 5 deletions(-)

Patch
diff mbox series 

diff --git a/include/libcamera/internal/camera_sensor.h b/include/libcamera/internal/camera_sensor.h
index 2a2f1f2c936d..17080ba32d37 100644
--- a/include/libcamera/internal/camera_sensor.h
+++ b/include/libcamera/internal/camera_sensor.h
@@ -92,6 +92,7 @@  public:
 	virtual ~CameraSensorFactoryBase() = default;
 
 	static std::unique_ptr<CameraSensor> create(MediaEntity *entity);
+	static std::string generateId(const MediaEntity *entity);
 
 	const std::string &name() const { return name_; }
 	int priority() const { return priority_; }
diff --git a/src/libcamera/sensor/camera_sensor.cpp b/src/libcamera/sensor/camera_sensor.cpp
index 580d3626216c..05654354ea1b 100644
--- a/src/libcamera/sensor/camera_sensor.cpp
+++ b/src/libcamera/sensor/camera_sensor.cpp
@@ -13,6 +13,7 @@ 
 #include <libcamera/base/log.h>
 
 #include "libcamera/internal/media_object.h"
+#include "libcamera/internal/sysfs.h"
 
 /**
  * \file camera_sensor.h
@@ -474,6 +475,32 @@  std::unique_ptr<CameraSensor> CameraSensorFactoryBase::create(MediaEntity *entit
 	return nullptr;
 }
 
+/**
+ * \brief Generate a unique ID for a camera sensor
+ * \param[in] entity The media entity that corresponds to the camera sensor
+ *
+ * The ID is derived from the firmware description (device tree or ACPI) of the
+ * device associated with the sensor's media \a entity. It is unique and stable
+ * as long as the system firmware is not modified. Sensors that the firmware
+ * does not describe have no ID.
+ *
+ * The ID is computed from sysfs only, using the device numbers stored in the
+ * media graph, without opening or otherwise accessing the sensor device.
+ *
+ * \sa sysfs::firmwareNodePath()
+ *
+ * \return The sensor ID on success or an empty string on failure
+ */
+std::string CameraSensorFactoryBase::generateId(const MediaEntity *entity)
+{
+	const std::string devPath = sysfs::devicePath(entity->deviceMajor(),
+						      entity->deviceMinor());
+	if (devPath.empty())
+		return {};
+
+	return sysfs::firmwareNodePath(devPath);
+}
+
 /**
  * \fn CameraSensorFactoryBase::name()
  * \brief Retrieve the camera sensor factory name
diff --git a/src/libcamera/sensor/camera_sensor_legacy.cpp b/src/libcamera/sensor/camera_sensor_legacy.cpp
index 83e2c2593215..99661f6fd02e 100644
--- a/src/libcamera/sensor/camera_sensor_legacy.cpp
+++ b/src/libcamera/sensor/camera_sensor_legacy.cpp
@@ -302,10 +302,8 @@  int CameraSensorLegacy::init()
 
 int CameraSensorLegacy::generateId()
 {
-	const std::string devPath = subdev_->devicePath();
-
 	/* Try to get ID from firmware description. */
-	id_ = sysfs::firmwareNodePath(devPath);
+	id_ = CameraSensorFactoryBase::generateId(entity_);
 	if (!id_.empty())
 		return 0;
 
@@ -315,6 +313,8 @@  int CameraSensorLegacy::generateId()
 	 * Verify it's a platform device and construct ID from the device path
 	 * and model of sensor.
 	 */
+	const std::string devPath = sysfs::devicePath(entity_->deviceMajor(),
+						      entity_->deviceMinor());
 	if (devPath.find("/sys/devices/platform/", 0) == 0) {
 		id_ = devPath.substr(strlen("/sys/devices/")) + " " + model();
 		return 0;
diff --git a/src/libcamera/sensor/camera_sensor_raw.cpp b/src/libcamera/sensor/camera_sensor_raw.cpp
index 6344a34fc4c5..423b14af2890 100644
--- a/src/libcamera/sensor/camera_sensor_raw.cpp
+++ b/src/libcamera/sensor/camera_sensor_raw.cpp
@@ -37,7 +37,6 @@ 
 #include "libcamera/internal/camera_sensor_properties.h"
 #include "libcamera/internal/formats.h"
 #include "libcamera/internal/media_device.h"
-#include "libcamera/internal/sysfs.h"
 #include "libcamera/internal/v4l2_subdevice.h"
 
 namespace libcamera {
@@ -571,7 +570,7 @@  int CameraSensorRaw::initProperties()
 	properties_.set(properties::Model, utils::toAscii(model_));
 
 	/* Generate a unique ID for the sensor. */
-	id_ = sysfs::firmwareNodePath(subdev_->devicePath());
+	id_ = CameraSensorFactoryBase::generateId(entity_);
 	if (id_.empty()) {
 		LOG(CameraSensor, Error) << "Can't generate sensor ID";
 		return -EINVAL;