v4l2: v4l2_compat: Add eventfd signaling to support polling

To support polling, we need to be able to signal when data is
available to be read (POLLIN), as well as events (POLLPRI). Add the
necessary calls to eventfd to allow signaling POLLIN. We signal POLLIN
by writing writing to the eventfd, and clear it by reading from the
eventfd, upon VIDIOC_DQBUF.

Note that eventfd does not support signaling POLLPRI, so we don't yet
support V4L2 events.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/v4l2/v4l2_camera_proxy.h b/src/v4l2/v4l2_camera_proxy.h
index af9f9bbe..7c65c886 100644
--- a/src/v4l2/v4l2_camera_proxy.h
+++ b/src/v4l2/v4l2_camera_proxy.h
@@ -33,6 +33,8 @@ public:
 
 	int ioctl(unsigned long request, void *arg);
 
+	void bind(int fd);
+
 private:
 	bool validateBufferType(uint32_t type);
 	bool validateMemoryType(uint32_t memory);
@@ -77,6 +79,8 @@ private:
 	std::map<void *, unsigned int> mmaps_;
 
 	std::unique_ptr<V4L2Camera> vcam_;
+
+	int efd_;
 };
 
 #endif /* __V4L2_CAMERA_PROXY_H__ */