trying to figure out how videobuf2 works

diff --git a/vdummy.c b/vdummy.c
index e01eba6..bf04eec 100644 (file)
--- a/vdummy.c
+++ b/vdummy.c
@@ -35,6 +35,7 @@ static void stop_streaming(struct vb2_queue *vbq);
 
 
 static int update_frame(int xsz, int ysz);
+static int gen_frame(void);
 
 
 module_init(init);
@@ -57,7 +58,8 @@ static unsigned char *frame;
 static int frame_size;
 
 static int streaming;
-static struct buffer *buflist;
+static spinlock_t blist_lock;
+static struct buffer *buflist, *buflist_tail;
 static int seqno;
 
 
@@ -261,20 +263,44 @@ static int buf_prepare(struct vb2_buffer *vb)
 
 static void buf_queue(struct vb2_buffer *vb)
 {
-       memcpy(vb2_plane_vaddr(vb, 0), frame, frame_size);
-       vb2_buffer_done(vb, VB2_BUF_STATE_DONE);
+       struct buffer *buf = (struct buffer*)((char*)vb - offsetof(struct buffer, vb));
+
+       spin_lock(&blist_lock);
+       if(buflist) {
+               buflist_tail->next = buf;
+               buflist_tail = buf;
+       } else {
+               buflist = buflist_tail = buf;
+       }
+       buf->next = 0;
+       spin_unlock(&blist_lock);
+}
+
+static void clear_queue(enum vb2_buffer_state st)
+{
+       spin_lock(&blist_lock);
+       while(buflist) {
+               struct buffer *buf = buflist;
+               buflist = buflist->next;
+               vb2_buffer_done(&buf->vb, st);
+       }
+       buflist = buflist_tail = 0;
+       spin_unlock(&blist_lock);
 }
 
 static int start_streaming(struct vb2_queue *vbq, unsigned int count)
 {
        streaming = 1;
        seqno = 0;
+
+       gen_frame();
        return 0;
 }
 
 static void stop_streaming(struct vb2_queue *vbq)
 {
        streaming = 0;
+       clear_queue(VB2_BUF_STATE_ERROR);
 }
 
 static int update_frame(int xsz, int ysz)
@@ -309,5 +335,30 @@ static int update_frame(int xsz, int ysz)
                        *tmp++ = (val << 2) & 0xff;
                }
        }
+
+       return 0;
+}
+
+static int gen_frame(void)
+{
+       struct buffer *buf = 0;
+
+       spin_lock(&blist_lock);
+       if(buflist) {
+               buf = buflist;
+               buflist = buflist->next;
+               if(!buflist) buflist_tail = 0;
+       }
+       spin_unlock(&blist_lock);
+
+       if(buf) {
+               memcpy(vb2_plane_vaddr(&buf->vb, 0), frame, frame_size);
+
+               /*v4l2_get_timestamp(&buf->vb.v4l2_buf.timestamp);
+               buf->vb.v4l2_buf.sequence = seqno++;
+               buf->vb.v4l2_buf.field = V4L2_FIELD_NONE;*/
+               vb2_buffer_done(&buf->vb, VB2_BUF_STATE_DONE);
+       }
+
        return 0;
 }