[media] media: mx3_camera: buf_init() add buffer state check

This patch checks the state of the buffer when calling .buf_init() method.
This is needed for the USERPTR buffer type, because in that case
.buf_init() is called every time a buffer is queued, and not only once
during the preparation stage, like in the MMAP case. Without this check
buffers get initialised repeatedly, which also leads to the allocation
of new DMA descriptors, of which there is only a final relatively small
number available. Both MMAP and USERPTR methods were successfully tested.

Signed-off-by: Alex Gershgorin <alexg@meprolight.com>
[g.liakhovetski@gmx.de: remove mx3_camera_buffer::state completely]
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/mx3_camera.c

@@ -61,15 +61,9 @@
 
 #define MAX_VIDEO_MEM 16
 
-enum csi_buffer_state {
-	CSI_BUF_NEEDS_INIT,
-	CSI_BUF_PREPARED,
-};
-
 struct mx3_camera_buffer {
 	/* common v4l buffer stuff -- must be first */
 	struct vb2_buffer			vb;
-	enum csi_buffer_state			state;
 	struct list_head			queue;
 
 	/* One descriptot per scatterlist (per frame) */
@@ -285,7 +279,7 @@ static void mx3_videobuf_queue(struct vb2_buffer *vb)
 		goto error;
 	}
 
-	if (buf->state == CSI_BUF_NEEDS_INIT) {
+	if (!buf->txd) {
 		sg_dma_address(sg)	= vb2_dma_contig_plane_dma_addr(vb, 0);
 		sg_dma_len(sg)		= new_size;
 
@@ -298,7 +292,6 @@ static void mx3_videobuf_queue(struct vb2_buffer *vb)
 		txd->callback_param	= txd;
 		txd->callback		= mx3_cam_dma_done;
 
-		buf->state		= CSI_BUF_PREPARED;
 		buf->txd		= txd;
 	} else {
 		txd = buf->txd;
@@ -385,7 +378,6 @@ static void mx3_videobuf_release(struct vb2_buffer *vb)
 
 	/* Doesn't hurt also if the list is empty */
 	list_del_init(&buf->queue);
-	buf->state = CSI_BUF_NEEDS_INIT;
 
 	if (txd) {
 		buf->txd = NULL;
@@ -405,13 +397,13 @@ static int mx3_videobuf_init(struct vb2_buffer *vb)
 	struct mx3_camera_dev *mx3_cam = ici->priv;
 	struct mx3_camera_buffer *buf = to_mx3_vb(vb);
 
-	/* This is for locking debugging only */
-	INIT_LIST_HEAD(&buf->queue);
-	sg_init_table(&buf->sg, 1);
+	if (!buf->txd) {
+		/* This is for locking debugging only */
+		INIT_LIST_HEAD(&buf->queue);
+		sg_init_table(&buf->sg, 1);
 
-	buf->state = CSI_BUF_NEEDS_INIT;
-
-	mx3_cam->buf_total += vb2_plane_size(vb, 0);
+		mx3_cam->buf_total += vb2_plane_size(vb, 0);
+	}
 
 	return 0;
 }