From: John Tsiombikas <nuclear@mutantstargoat.com>
Date: Fri, 12 May 2017 00:14:42 +0000 (+0300)
Subject: trying to figure out how videobuf2 works
X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=vdummy;a=commitdiff_plain;h=019a9d6eb5da203b03caa54bcc30ab2507606cbe

trying to figure out how videobuf2 works
---

diff --git a/vdummy.c b/vdummy.c
index e01eba6..bf04eec 100644
--- 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;
 }