[RFC] soundwire: add runtime BPT support

drivers/soundwire/generic_bandwidth_allocation.c

@@ -97,9 +97,9 @@ static void sdw_compute_dp0_slave_ports(struct sdw_master_runtime *m_rt)
 		list_for_each_entry(p_rt, &s_rt->port_list, port_node) {
 			sdw_fill_xport_params(&p_rt->transport_params, p_rt->num, false,
 					      SDW_BLK_GRP_CNT_1, bus->params.col, 0, 0, 1,
-					      bus->params.col - 1, SDW_BLK_PKG_PER_PORT, 0x0);
+					      bus->bpt_hstop, SDW_BLK_PKG_PER_PORT, 0x0);
 
-			sdw_fill_port_params(&p_rt->port_params, p_rt->num, bus->params.col - 1,
+			sdw_fill_port_params(&p_rt->port_params, p_rt->num, bus->bpt_hstop,
 					     SDW_PORT_FLOW_MODE_ISOCH, SDW_PORT_DATA_MODE_NORMAL);
 		}
 	}
@@ -113,9 +113,9 @@ static void sdw_compute_dp0_master_ports(struct sdw_master_runtime *m_rt)
 	list_for_each_entry(p_rt, &m_rt->port_list, port_node) {
 		sdw_fill_xport_params(&p_rt->transport_params, p_rt->num, false,
 				      SDW_BLK_GRP_CNT_1, bus->params.col, 0, 0, 1,
-				      bus->params.col - 1, SDW_BLK_PKG_PER_PORT, 0x0);
+				      bus->bpt_hstop, SDW_BLK_PKG_PER_PORT, 0x0);
 
-		sdw_fill_port_params(&p_rt->port_params, p_rt->num, bus->params.col - 1,
+		sdw_fill_port_params(&p_rt->port_params, p_rt->num, bus->bpt_hstop,
 				     SDW_PORT_FLOW_MODE_ISOCH, SDW_PORT_DATA_MODE_NORMAL);
 	}
 }
@@ -190,8 +190,8 @@ static void sdw_compute_master_ports(struct sdw_master_runtime *m_rt,
 	sdw_compute_slave_ports(m_rt, &t_data);
 }
 
-static void _sdw_compute_port_params(struct sdw_bus *bus,
-				     struct sdw_group_params *params, int count)
+static void _sdw_compute_port_params(struct sdw_bus *bus, struct sdw_group_params *params,
+				     int count, bool update_bpt_hstop)
 {
 	struct sdw_master_runtime *m_rt;
 	int port_bo, i, l;
@@ -216,10 +216,23 @@ static void _sdw_compute_port_params(struct sdw_bus *bus,
 				if (m_rt->stream->state > SDW_STREAM_DISABLED ||
 				    m_rt->stream->state < SDW_STREAM_CONFIGURED)
 					continue;
+				/* BPT stream is handled in sdw_compute_dp0_port_params */
+				if (m_rt->stream->type == SDW_STREAM_BPT)
+					continue;
 				sdw_compute_master_ports(m_rt, &params[i], &port_bo, hstop);
 			}
 
 			hstop = hstop - params[i].hwidth;
+			if (l == 0 && update_bpt_hstop && bus->bpt_hstop > hstop) {
+				/* Assume BPT stream uses lane 0 */
+				/*
+				 * hstart = hstop - params->hwidth + 1.
+				 * At this point after hstop = hstop - params[i].hwidth above,
+				 * the hstart is equal to hstop + 1, and bus->bpt_hstop should
+				 * be hstart - 1. so we can set bpt_hstop to hstop directly.
+				 */
+				bus->bpt_hstop = hstop;
+			}
 		}
 	}
 }
@@ -359,6 +372,9 @@ static int sdw_get_group_count(struct sdw_bus *bus,
 	}
 
 	list_for_each_entry(m_rt, &bus->m_rt_list, bus_node) {
+		if (m_rt->stream->type == SDW_STREAM_BPT)
+			continue;
+
 		if (m_rt->stream->state == SDW_STREAM_DEPREPARED)
 			continue;
 
@@ -415,7 +431,7 @@ static int sdw_compute_port_params(struct sdw_bus *bus, struct sdw_stream_runtim
 	if (ret < 0)
 		goto free_params;
 
-	_sdw_compute_port_params(bus, params, group.count);
+	_sdw_compute_port_params(bus, params, group.count, stream->type == SDW_STREAM_BPT);
 
 free_params:
 	kfree(params);
@@ -555,6 +571,7 @@ static int sdw_compute_bus_params(struct sdw_bus *bus)
 	unsigned int curr_dr_freq = 0;
 	int i, l, clk_values, ret;
 	bool is_gear = false;
+	int available_col;
 	int m_lane = 0;
 	u32 *clk_buf;
 
@@ -570,23 +587,47 @@ static int sdw_compute_bus_params(struct sdw_bus *bus)
 		clk_buf = NULL;
 	}
 
-	/* If dynamic scaling is not supported, don't try higher freq */
-	if (!is_clock_scaling_supported(bus))
+	/*
+	 * If dynamic scaling is not supported, don't try higher freq.
+	 * Use the maximum freq to get maximum bandwidth and no need to try another freq
+	 * if BPT stream is running
+	 */
+	if (!is_clock_scaling_supported(bus) || bus->bpt_stream_refcount)
 		clk_values = 1;
 
+	if (!mstr_prop->default_frame_rate || !mstr_prop->default_row)
+		return -EINVAL;
+
 	for (i = 0; i < clk_values; i++) {
+		int total_col;
+
 		if (!clk_buf)
 			curr_dr_freq = bus->params.max_dr_freq;
 		else
 			curr_dr_freq = (is_gear) ?
 				(bus->params.max_dr_freq >>  clk_buf[i]) :
 				clk_buf[i] * SDW_DOUBLE_RATE_FACTOR;
 
-		if (curr_dr_freq * (mstr_prop->default_col - 1) >=
-		    bus->params.bandwidth * mstr_prop->default_col)
+		/* Use maximum freq to get maximum bandwidth if BPT stream is running */
+		if (bus->bpt_stream_refcount)
+			curr_dr_freq = bus->params.max_dr_freq;
+
+		total_col = curr_dr_freq / mstr_prop->default_frame_rate / mstr_prop->default_row;
+
+		if (bus->bpt_stream_refcount)
+			available_col = total_col - bus->bpt_hstop - 1;
+		else
+			available_col = total_col;
+
+		/* If the bandwidth of the available columns is sufficient, then we are good */
+		if (curr_dr_freq * (available_col - 1) >=
+		    bus->params.bandwidth * available_col)
 			break;
 
 		list_for_each_entry(m_rt, &bus->m_rt_list, bus_node) {
+			/* BPT stream always uses lane 0 */
+			if (m_rt->stream->type == SDW_STREAM_BPT)
+				continue;
 			/*
 			 * Get the first s_rt that will be used to find the available lane that
 			 * can be used. No need to check all Peripherals because we can't use
@@ -642,9 +683,6 @@ static int sdw_compute_bus_params(struct sdw_bus *bus)
 		}
 	}
 
-	if (!mstr_prop->default_frame_rate || !mstr_prop->default_row)
-		return -EINVAL;
-
 	mstr_prop->default_col = curr_dr_freq / mstr_prop->default_frame_rate /
 				 mstr_prop->default_row;
 
@@ -659,6 +697,10 @@ static int sdw_compute_bus_params(struct sdw_bus *bus)
 	return 0;
 }
 
+#define SDW_DEFAULT_COL			4
+#define SDW_COL_RESERVED_FOR_AUDIO	2
+
+
 /**
  * sdw_compute_params: Compute bus, transport and port parameters
  *
@@ -674,9 +716,20 @@ int sdw_compute_params(struct sdw_bus *bus, struct sdw_stream_runtime *stream)
 	if (ret < 0)
 		return ret;
 
-	if (stream->type == SDW_STREAM_BPT) {
-		sdw_compute_dp0_port_params(bus);
-		return 0;
+	if (stream->type == SDW_STREAM_BPT && stream->state == SDW_STREAM_CONFIGURED) {
+		/*
+		 * Set the initial bpt_hstop when the BPT stream is preparing and it will be
+		 * updated in sdw_compute_port_params() below.
+		 */
+		bus->bpt_hstop = bus->params.col - 1;
+		/*
+		 * Reserve 2 columns for future audio stream if the bus->params.col is greater
+		 * than SDW_DEFAULT_COL (4) + reserved columns (2). And don't reserve columns
+		 * for future use otherwise. This ensures that the BPT stream will not meet the
+		 * bandwidth issue when there is no audio stream is open.
+		 */
+		if (bus->params.col >= (SDW_DEFAULT_COL + SDW_COL_RESERVED_FOR_AUDIO))
+			bus->bpt_hstop -= SDW_COL_RESERVED_FOR_AUDIO;
 	}
 
 	/* Compute transport and port params */
@@ -686,6 +739,16 @@ int sdw_compute_params(struct sdw_bus *bus, struct sdw_stream_runtime *stream)
 		return ret;
 	}
 
+	if (stream->type == SDW_STREAM_BPT) {
+		/* If there is only one column left, just use normal write. */
+		if (bus->bpt_hstop < 1) {
+			dev_err(bus->dev, "%s: No bandwidth for BPT stream\n",
+				__func__);
+			return -EAGAIN;
+		}
+		sdw_compute_dp0_port_params(bus);
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(sdw_compute_params);

drivers/soundwire/intel_ace2x.c

@@ -153,7 +153,7 @@ static int intel_ace2x_bpt_open_stream(struct sdw_intel *sdw, struct sdw_slave *
 	command = (msg->flags & SDW_MSG_FLAG_WRITE) ? 0 : 1;
 
 	ret = sdw_cdns_bpt_find_bandwidth(command, cdns->bus.params.row,
-					  cdns->bus.params.col,
+					  cdns->bus.bpt_hstop + 1,
 					  prop->default_frame_rate,
 					  &tx_dma_bandwidth, &rx_dma_bandwidth);
 	if (ret < 0)
@@ -166,7 +166,7 @@ static int intel_ace2x_bpt_open_stream(struct sdw_intel *sdw, struct sdw_slave *
 	/* Add up pdi buffer size and frame numbers of each BPT sections */
 	for (i = 0; i < msg->sections; i++) {
 		ret = sdw_cdns_bpt_find_buffer_sizes(command, cdns->bus.params.row,
-						     cdns->bus.params.col,
+						     cdns->bus.bpt_hstop + 1,
 						     msg->sec[i].len, SDW_BPT_MSG_MAX_BYTES,
 						     &data_per_frame, &pdi0_buffer_size_,
 						     &pdi1_buffer_size_, &num_frames_);
@@ -190,7 +190,7 @@ static int intel_ace2x_bpt_open_stream(struct sdw_intel *sdw, struct sdw_slave *
 	if (command) { /* read */
 		/* Get buffer size of a full frame */
 		ret = sdw_cdns_bpt_find_buffer_sizes(command, cdns->bus.params.row,
-						     cdns->bus.params.col,
+						     cdns->bus.bpt_hstop + 1,
 						     data_per_frame, SDW_BPT_MSG_MAX_BYTES,
 						     &data_per_frame, &pdi0_buf_size_pre_frame,
 						     &pdi1_buf_size_pre_frame, &fake_num_frames);

drivers/soundwire/stream.c

@@ -1237,18 +1237,10 @@ static struct sdw_master_runtime
 	struct sdw_master_runtime *m_rt, *walk_m_rt;
 	struct list_head *insert_after;
 
-	if (stream->type == SDW_STREAM_BPT) {
-		if (bus->stream_refcount > 0 || bus->bpt_stream_refcount > 0) {
-			dev_err(bus->dev, "%s: %d/%d audio/BPT stream already allocated\n",
-				__func__, bus->stream_refcount, bus->bpt_stream_refcount);
-			return ERR_PTR(-EBUSY);
-		}
-	} else {
-		if (bus->bpt_stream_refcount > 0) {
-			dev_err(bus->dev, "%s: BPT stream already allocated\n",
-				__func__);
-			return ERR_PTR(-EAGAIN);
-		}
+	if (stream->type == SDW_STREAM_BPT && bus->bpt_stream_refcount > 0) {
+		dev_err(bus->dev, "%s: BPT stream already allocated\n",
+			__func__);
+		return ERR_PTR(-EAGAIN);
 	}
 
 	m_rt = kzalloc(sizeof(*m_rt), GFP_KERNEL);
@@ -1484,8 +1476,11 @@ static int _sdw_prepare_stream(struct sdw_stream_runtime *stream,
 		if (update_params) {
 			/* Increment cumulative bus bandwidth */
 			/* TODO: Update this during Device-Device support */
-			bus->params.bandwidth += m_rt->stream->params.rate *
-				m_rt->ch_count * m_rt->stream->params.bps;
+			/* Don't count BPT stream bandwidth, it will use the remaining bandwidth */
+			if (m_rt->stream->type != SDW_STREAM_BPT) {
+				bus->params.bandwidth += m_rt->stream->params.rate *
+					m_rt->ch_count * m_rt->stream->params.bps;
+			}
 
 			/* Compute params */
 			if (bus->compute_params) {
@@ -1774,6 +1769,10 @@ static int _sdw_deprepare_stream(struct sdw_stream_runtime *stream)
 
 		multi_lane_bandwidth = 0;
 
+		/* Don't count BPT stream bandwidth, it will use the remaining bandwidth */
+		if (m_rt->stream->type == SDW_STREAM_BPT)
+			goto skip_bpt_stream;
+
 		list_for_each_entry(p_rt, &m_rt->port_list, port_node) {
 			if (!p_rt->lane)
 				continue;
@@ -1789,6 +1788,7 @@ static int _sdw_deprepare_stream(struct sdw_stream_runtime *stream)
 		bandwidth = m_rt->stream->params.rate * m_rt->ch_count * m_rt->stream->params.bps;
 		bus->params.bandwidth -= bandwidth - multi_lane_bandwidth;
 
+skip_bpt_stream:
 		/* Compute params */
 		if (bus->compute_params) {
 			ret = bus->compute_params(bus, stream);

include/linux/soundwire/sdw.h

@@ -985,6 +985,7 @@ struct sdw_stream_runtime {
  * @stream_refcount: number of streams currently using this bus
  * @btp_stream_refcount: number of BTP streams currently using this bus (should
  * be zero or one, multiple streams per link is not supported).
+ * @bpt_hstop: The hstop of the BPT stream.
  * @bpt_stream: pointer stored to handle BTP streams.
  * @ops: Master callback ops
  * @port_ops: Master port callback ops
@@ -1025,6 +1026,7 @@ struct sdw_bus {
 	struct sdw_bus_params params;
 	int stream_refcount;
 	int bpt_stream_refcount;
+	int bpt_hstop;
 	struct sdw_stream_runtime *bpt_stream;
 	const struct sdw_master_ops *ops;
 	const struct sdw_master_port_ops *port_ops;