media: rockchip/rga: Fix broken .start_streaming

Currently, rga_buf_start_streaming() is expecting
pm_runtime_get_sync to return zero on success, which
is wrong.

As per the documentation, pm_runtime_get_sync increments
the device's usage counter and return its result.
This means it will typically return a positive integer
on success and a negative error code.

Therefore, rockchip-rga driver is currently unusable
failing to start_streaming in most cases. Fix it and
while here, cleanup the buffer return-to-core logic.

Fixes: f7e7b48e ("[media] rockchip/rga: v4l2 m2m support")
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Jacob Chen <jacob-chen@iotwrt.com>
[hans.verkuil@cisco.com: fix line over 80 cols warning]
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/rockchip/rga/rga-buf.c

@@ -64,43 +64,44 @@ static void rga_buf_queue(struct vb2_buffer *vb)
 	v4l2_m2m_buf_queue(ctx->fh.m2m_ctx, vbuf);
 }
 
+static void rga_buf_return_buffers(struct vb2_queue *q,
+				   enum vb2_buffer_state state)
+{
+	struct rga_ctx *ctx = vb2_get_drv_priv(q);
+	struct vb2_v4l2_buffer *vbuf;
+
+	for (;;) {
+		if (V4L2_TYPE_IS_OUTPUT(q->type))
+			vbuf = v4l2_m2m_src_buf_remove(ctx->fh.m2m_ctx);
+		else
+			vbuf = v4l2_m2m_dst_buf_remove(ctx->fh.m2m_ctx);
+		if (!vbuf)
+			break;
+		v4l2_m2m_buf_done(vbuf, state);
+	}
+}
+
 static int rga_buf_start_streaming(struct vb2_queue *q, unsigned int count)
 {
 	struct rga_ctx *ctx = vb2_get_drv_priv(q);
 	struct rockchip_rga *rga = ctx->rga;
-	int ret, i;
+	int ret;
 
 	ret = pm_runtime_get_sync(rga->dev);
-
-	if (!ret)
-		return 0;
-
-	for (i = 0; i < q->num_buffers; ++i) {
-		if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE) {
-			v4l2_m2m_buf_done(to_vb2_v4l2_buffer(q->bufs[i]),
-					  VB2_BUF_STATE_QUEUED);
-		}
+	if (ret < 0) {
+		rga_buf_return_buffers(q, VB2_BUF_STATE_QUEUED);
+		return ret;
 	}
 
-	return ret;
+	return 0;
 }
 
 static void rga_buf_stop_streaming(struct vb2_queue *q)
 {
 	struct rga_ctx *ctx = vb2_get_drv_priv(q);
 	struct rockchip_rga *rga = ctx->rga;
-	struct vb2_v4l2_buffer *vbuf;
-
-	for (;;) {
-		if (V4L2_TYPE_IS_OUTPUT(q->type))
-			vbuf = v4l2_m2m_src_buf_remove(ctx->fh.m2m_ctx);
-		else
-			vbuf = v4l2_m2m_dst_buf_remove(ctx->fh.m2m_ctx);
-		if (!vbuf)
-			break;
-		v4l2_m2m_buf_done(vbuf, VB2_BUF_STATE_ERROR);
-	}
 
+	rga_buf_return_buffers(q, VB2_BUF_STATE_ERROR);
 	pm_runtime_put(rga->dev);
 }