linux-kernel - [PATCH 4/7] soundwire: cadence: export sdw_cdns_bpt_find

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Message-ID: <20251014031450.3781789-5-yung-chuan.liao@linux.intel.com>
Date: Tue, 14 Oct 2025 11:14:47 +0800
From: Bard Liao <yung-chuan.liao@...ux.intel.com>
To: linux-sound@...r.kernel.org,
	vkoul@...nel.org
Cc: vinod.koul@...aro.org,
	linux-kernel@...r.kernel.org,
	pierre-louis.bossart@...ux.dev,
	bard.liao@...el.com
Subject: [PATCH 4/7] soundwire: cadence: export sdw_cdns_bpt_find_bandwidth

Currently, we calculate the required bandwidth after the PDI buffer size
is calculated. However as we need to add some fake frame to align the
data block size, the final PDI size and the frame number will change.
Besides, we need the required bandwidth to decide the DMA channel number
and the channel number will be used to calculate the data block size.
Therefore, we calculate the required bandwidth and export a helper for
the caller to get the required bandwidth.

Signed-off-by: Bard Liao <yung-chuan.liao@...ux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>
---
 drivers/soundwire/cadence_master.c | 30 ++++++++++++++++++++++++++++++
 drivers/soundwire/cadence_master.h |  5 +++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index 178341410909..57671f9b3e9c 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -2094,6 +2094,36 @@ static unsigned int sdw_cdns_read_pdi1_buffer_size(unsigned int actual_data_size
 	return total * 2;
 }
 
+int sdw_cdns_bpt_find_bandwidth(int command, /* 0: write, 1: read */
+				int row, int col, int frame_rate,
+				unsigned int *tx_dma_bandwidth,
+				unsigned int *rx_dma_bandwidth)
+{
+	unsigned int bpt_bits = row * (col - 1);
+	unsigned int bpt_bytes = bpt_bits >> 3;
+	unsigned int pdi0_buffer_size;
+	unsigned int pdi1_buffer_size;
+	unsigned int data_per_frame;
+
+	data_per_frame = sdw_cdns_bra_actual_data_size(bpt_bytes);
+	if (!data_per_frame)
+		return -EINVAL;
+
+	if (command == 0) {
+		pdi0_buffer_size = sdw_cdns_write_pdi0_buffer_size(data_per_frame);
+		pdi1_buffer_size = SDW_CDNS_WRITE_PDI1_BUFFER_SIZE;
+	} else {
+		pdi0_buffer_size = SDW_CDNS_READ_PDI0_BUFFER_SIZE;
+		pdi1_buffer_size = sdw_cdns_read_pdi1_buffer_size(data_per_frame);
+	}
+
+	*tx_dma_bandwidth = pdi0_buffer_size * 8 * frame_rate;
+	*rx_dma_bandwidth = pdi1_buffer_size * 8 * frame_rate;
+
+	return 0;
+}
+EXPORT_SYMBOL(sdw_cdns_bpt_find_bandwidth);
+
 int sdw_cdns_bpt_find_buffer_sizes(int command, /* 0: write, 1: read */
 				   int row, int col, unsigned int data_bytes,
 				   unsigned int requested_bytes_per_frame,
diff --git a/drivers/soundwire/cadence_master.h b/drivers/soundwire/cadence_master.h
index 9373426c7f63..6830d7f2d772 100644
--- a/drivers/soundwire/cadence_master.h
+++ b/drivers/soundwire/cadence_master.h
@@ -209,6 +209,11 @@ void sdw_cdns_config_update(struct sdw_cdns *cdns);
 int sdw_cdns_config_update_set_wait(struct sdw_cdns *cdns);
 
 /* SoundWire BPT/BRA helpers to format data */
+int sdw_cdns_bpt_find_bandwidth(int command, /* 0: write, 1: read */
+				int row, int col, int frame_rate,
+				unsigned int *tx_dma_bandwidth,
+				unsigned int *rx_dma_bandwidth);
+
 int sdw_cdns_bpt_find_buffer_sizes(int command, /* 0: write, 1: read */
 				   int row, int col, unsigned int data_bytes,
 				   unsigned int requested_bytes_per_frame,
-- 
2.43.0