vc04_services: codec: Allocate the max number of buffers on the VPU

The VPU's API can't match the use of VIDIOC_CREATE_BUFS to add buffers
to the internal pool whilst a port is enabled, therefore allocate
the maximum number of buffers possible in V4L2 to avoid the issue.
As these are only buffer headers, the overhead is relatively small.

Signed-off-by: Dave Stevenson <[email protected]>

drivers/staging/vc04_services/bcm2835-codec/bcm2835-v4l2-codec.c

@@ -2871,8 +2871,14 @@ static int bcm2835_codec_queue_setup(struct vb2_queue *vq,
 
 	if (*nbuffers < port->minimum_buffer.num)
 		*nbuffers = port->minimum_buffer.num;
-	/* Add one buffer to take an EOS */
-	port->current_buffer.num = *nbuffers + 1;
+
+	/*
+	 * The VPU uses this number to allocate a pool of headers at port_enable.
+	 * We can't increase it later, so use of CREATE_BUFS is going to result
+	 * in bad things happening. Adopt worst-case allocation, and add one
+	 * buffer to take an EOS
+	 */
+	port->current_buffer.num = VB2_MAX_FRAME + 1;
 
 	return 0;
 }