libcamera: streams: extend stream configuration with buffer count

The camera needs to be configured with the number of buffers required to
satisfy the applications use case. While the application can request any
number of buffers, the pipeline must take the constraints of the Linux
driver into consideration.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

include/libcamera/stream.h

@@ -17,6 +17,8 @@ struct StreamConfiguration {
 	unsigned int width;
 	unsigned int height;
 	unsigned int pixelFormat;
+
+	unsigned int bufferCount;
 };
 
 } /* namespace libcamera */

src/libcamera/stream.cpp

@@ -73,4 +73,9 @@ namespace libcamera {
  * format described in V4L2 using the V4L2_PIX_FMT_* definitions.
  */
 
+/**
+ * \var StreamConfiguration::bufferCount
+ * \brief Requested number of buffers to allocate for the stream
+ */
+
 } /* namespace libcamera */