media: coda: flush bitstream ring buffer on decoder restart

The bitstream ringbuffer might be in an underrun state after draining,
or it might still contain unread data if the previous decoder stop
command was flagged as immediate. Flush the bitstream ring buffer
during V4L2_DEC_CMD_START to get into a well defined state. Also fill
the bitstream with buffers that have been queued during draining,
to resume decoding immediately.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/coda/coda-bit.c

@@ -199,6 +199,26 @@ static int coda_h264_bitstream_pad(struct coda_ctx *ctx, u32 size)
 	return (n < size) ? -ENOSPC : 0;
 }
 
+int coda_bitstream_flush(struct coda_ctx *ctx)
+{
+	int ret;
+
+	if (ctx->inst_type != CODA_INST_DECODER || !ctx->use_bit)
+		return 0;
+
+	ret = coda_command_sync(ctx, CODA_COMMAND_DEC_BUF_FLUSH);
+	if (ret < 0) {
+		v4l2_err(&ctx->dev->v4l2_dev, "failed to flush bitstream\n");
+		return ret;
+	}
+
+	kfifo_init(&ctx->bitstream_fifo, ctx->bitstream.vaddr,
+		   ctx->bitstream.size);
+	coda_kfifo_sync_to_device_full(ctx);
+
+	return 0;
+}
+
 static int coda_bitstream_queue(struct coda_ctx *ctx, const u8 *buf, u32 size)
 {
 	u32 n = kfifo_in(&ctx->bitstream_fifo, buf, size);

drivers/media/platform/coda/coda-common.c

@@ -1052,6 +1052,7 @@ static int coda_decoder_cmd(struct file *file, void *fh,
 			    struct v4l2_decoder_cmd *dc)
 {
 	struct coda_ctx *ctx = fh_to_ctx(fh);
+	struct coda_dev *dev = ctx->dev;
 	struct vb2_queue *dst_vq;
 	int ret;
 
@@ -1061,10 +1062,16 @@ static int coda_decoder_cmd(struct file *file, void *fh,
 
 	switch (dc->cmd) {
 	case V4L2_DEC_CMD_START:
+		mutex_lock(&ctx->bitstream_mutex);
+		mutex_lock(&dev->coda_mutex);
+		coda_bitstream_flush(ctx);
+		mutex_unlock(&dev->coda_mutex);
 		dst_vq = v4l2_m2m_get_vq(ctx->fh.m2m_ctx,
 					 V4L2_BUF_TYPE_VIDEO_CAPTURE);
 		vb2_clear_last_buffer_dequeued(dst_vq);
 		ctx->bit_stream_param &= ~CODA_BIT_STREAM_END_FLAG;
+		coda_fill_bitstream(ctx, NULL);
+		mutex_unlock(&ctx->bitstream_mutex);
 		break;
 	case V4L2_DEC_CMD_STOP:
 		/* Set the stream-end flag on this context */

drivers/media/platform/coda/coda.h

@@ -322,6 +322,7 @@ static inline bool coda_bitstream_can_fetch_past(struct coda_ctx *ctx,
 }
 
 bool coda_bitstream_can_fetch_past(struct coda_ctx *ctx, unsigned int pos);
+int coda_bitstream_flush(struct coda_ctx *ctx);
 
 void coda_bit_stream_end_flag(struct coda_ctx *ctx);