[libcamera-devel] [PATCH] android: camera_hal_manager: Fail on no cameras

[Jacopo Mondi]

The CameraHalManager initialization tries to start the
libcamera::CameraManager which enumerate the registered cameras.

When initialization is called too early during system boot, it might
happen that the media graphs are still being registered to user-space
preventing any pipeline handler to match and register cameras.

If that happens, the CameraHalManager silently accepts that no
cameras are available in the system, reporting that information
to the camera stack:

cros_camera_service[2054]: (5) StartOnThread(): Camera module "libcamera camera HALv3 module" has 0 built-in camera(s)
cros_camera_service[2054]: (5) StartOnThread(): SuperHAL started with 1 modules and 0 built-in cameras
CameraProviderManager: Camera provider legacy/0 ready with 0 camera devices

Fix this by returning an error code if no camera is registered in the
system at the time CameraHalManager::init() is called. The camera
framework then tries to re-load the HAL module later in time, hopefully
after the media device dependencies have been registered:

2020-07-21T12:26:37.903456+02:00 INFO cros_camera_service[2054]: (5) StartOnThread(): Camera module "libcamera camera HALv3 module" has 0 built-in camera(s)
2020-07-21T12:26:37.903521+02:00 INFO cros_camera_service[2054]: (5) StartOnThread(): SuperHAL started with 1 modules and 0 built-in cameras
....
2020-07-21T12:30:36.662877+02:00 INFO cros_camera_service[5908]: (5910) StartOnThread(): Camera module "libcamera camera HALv3 module" has 2 built-in camera(s)
2020-07-21T12:30:36.663196+02:00 INFO cros_camera_service[5908]: (5910) StartOnThread(): SuperHAL started with 1 modules and 2 built-in cameras

Return -ENODEV as according to camera_common.h specification is the
only supported error code. The CrOS HAL adapter does not distinguish
between that and other negative values, so it does not really make
a difference.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/android/camera_hal_manager.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/android/camera_hal_manager.cpp b/src/android/camera_hal_manager.cpp
index 02b6418fb36d..e967d210e547 100644
--- a/src/android/camera_hal_manager.cpp
+++ b/src/android/camera_hal_manager.cpp
@@ -73,6 +73,17 @@ int CameraHalManager::init()
 		++index;
 	}
 
+	/*
+	 * If no pipeline has registered cameras, defer initialization to give
+	 * time to media devices to register to user-space.
+	 */
+	if (index == 0) {
+		LOG(HAL, Debug) << "Defer CameraHALManager initialization";
+		delete cameraManager_;
+		cameraManager_ = nullptr;
+		return -ENODEV;
+	}
+
 	return 0;
 }
 
-- 
2.27.0