pipeline: add negotiation before propagating params

For different connected pipelines, they are usually connected via a
component with >1 source or sink buffers, as most of those components
don't have ability to converse frame format or sample rate, we need add
a params negotiation mechanism between those pipelines.

If all buffers are iterated in the params propagation direction, no
negotiation needed, otherwise we need to iterate all other buffers in
the opposite direction, to make sure all connected buffers have chance
to take part in the negotiation.

The negotiation should happen before we can propagate the params
further, when doing negotiation in a branch/buffer, we should check:
If a branch is active, check if params is matched, return error to
reject the whole .params() requirement if not.
If a branch is inactive, force update the params to its calling buffer,
to make sure all branches are aligned on the format.

We are propagating the params to branched buffer, and the subsequent
component's .params() or .prepare() should be responsible to calibrate
the buffer params if needed. For example, a component who has different
channels buffers should explicitly configure the channels for its
branched buffers (the ones connected to another pipeline).

Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>

Author: keyonjie

src/audio/pipeline.c

@@ -389,11 +389,64 @@ static int pipeline_comp_hw_params(struct comp_dev *current,
 	return 0;
 }
 
+static int pipeline_comp_params_neg(struct comp_dev *current,
+				    struct comp_buffer *calling_buf,
+				    struct pipeline_walk_context *ctx,
+				    int dir)
+{
+	struct pipeline_data *ppl_data = ctx->comp_data;
+	uint32_t flags = 0;
+	int err = 0;
+
+	pipe_dbg(ppl_data->p, "pipeline_comp_params_neg(), current->comp.id = %u, dir = %u",
+		 dev_comp_id(current), dir);
+
+	/* check if 'current' is already configured */
+	if (current->state != COMP_STATE_INIT &&
+	    current->state != COMP_STATE_READY) {
+		/* return 0 if params matches */
+		if (buffer_params_match(calling_buf,
+					&ppl_data->params->params,
+					BUFF_PARAMS_FRAME_FMT |
+					BUFF_PARAMS_RATE))
+			return 0;
+		/*
+		 * the param is conflict with an active pipeline,
+		 * drop an error and reject the .params() command.
+		 */
+		pipe_err(ppl_data->p, "pipeline_comp_params_neg(): params conflict with existed active pipeline!");
+		return -EINVAL;
+	}
+
+	/*
+	 * Negotiation only happen when the current component has > 1
+	 * source or sink, we are propagating the params to branched
+	 * buffers, and the subsequent component's .params() or .prepare()
+	 * should be responsible for calibrating if needed. For example,
+	 * a component who has different channels input/output buffers
+	 * should explicitly configure the channels of the branched buffers.
+	 */
+	if (calling_buf) {
+		buffer_lock(calling_buf, &flags);
+		err = buffer_set_params(calling_buf,
+					&ppl_data->params->params,
+					BUFFER_UPDATE_FORCE);
+		buffer_unlock(calling_buf, flags);
+	}
+
+	return err;
+}
+
 static int pipeline_comp_params(struct comp_dev *current,
 				struct comp_buffer *calling_buf,
 				struct pipeline_walk_context *ctx, int dir)
 {
 	struct pipeline_data *ppl_data = ctx->comp_data;
+	struct pipeline_walk_context param_neg_ctx = {
+		.comp_func = pipeline_comp_params_neg,
+		.comp_data = ppl_data,
+		.skip_incomplete = true,
+	};
 	int stream_direction = ppl_data->params->params.direction;
 	int end_type;
 	int err;
@@ -427,6 +480,11 @@ static int pipeline_comp_params(struct comp_dev *current,
 	if (current->state == COMP_STATE_ACTIVE)
 		return 0;
 
+	/* do params negotiation with other branches(opposite direction) */
+	err = pipeline_for_each_comp(current, &param_neg_ctx, !dir);
+	if (err < 0 || err == PPL_STATUS_PATH_STOP)
+		return err;
+
 	/* set comp direction */
 	current->direction = ppl_data->params->params.direction;