[PATCH 1/5] soundwire: cadence_master: add BRA_NumBytes[8] support

From: Bard Liao

Date: Tue Jun 30 2026 - 08:56:40 EST


The header[0] bit definitions are:
Header[0] bits 7 – 6: BRA_HeaderType
Header[0] bits 5 – 2: BRA_DeviceAddress[3:0]
Header[0] bit 1 BRA_Opcode 1 => Write, 0 => Read
Header[0] bit 0 BRA_NumBytes[8]
And the header[1] indicates the BRA_NumBytes[7:0]. The existing code
doesn't handle BRA_NumBytes[8] therefore the maximum BRA number of a
frame is limited to 255.

Fixes: fe8a9cf75c1e ("soundwire: pass sdw_bpt_section to cdns BPT helpers")
Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@xxxxxxxxxxxxxxx>
---
drivers/soundwire/cadence_master.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c
index b8b62735c893..99414e71428b 100644
--- a/drivers/soundwire/cadence_master.c
+++ b/drivers/soundwire/cadence_master.c
@@ -2359,7 +2359,9 @@ int sdw_cdns_prepare_write_dma_buffer(u8 dev_num, struct sdw_bpt_section *sec, i
p_data = sec[i].buf;

while (section_size >= data_per_frame) {
- header[1] = data_per_frame;
+ header[0] &= ~BIT(0);
+ header[0] |= (data_per_frame >> 8) & BIT(0);
+ header[1] = data_per_frame & 0xFF;
header[2] = start_register >> 24 & 0xFF;
header[3] = start_register >> 16 & 0xFF;
header[4] = start_register >> 8 & 0xFF;
@@ -2385,7 +2387,9 @@ int sdw_cdns_prepare_write_dma_buffer(u8 dev_num, struct sdw_bpt_section *sec, i
}

if (section_size) {
- header[1] = section_size;
+ header[0] &= ~BIT(0);
+ header[0] |= (section_size >> 8) & BIT(0);
+ header[1] = section_size & 0xFF;
header[2] = start_register >> 24 & 0xFF;
header[3] = start_register >> 16 & 0xFF;
header[4] = start_register >> 8 & 0xFF;
@@ -2436,7 +2440,9 @@ int sdw_cdns_prepare_read_dma_buffer(u8 dev_num, struct sdw_bpt_section *sec, in
start_register = sec[i].addr;
data_size = sec[i].len;
while (data_size >= data_per_frame) {
- header[1] = data_per_frame;
+ header[0] &= ~BIT(0);
+ header[0] |= (data_per_frame >> 8) & BIT(0);
+ header[1] = data_per_frame & 0xFF;
header[2] = start_register >> 24 & 0xFF;
header[3] = start_register >> 16 & 0xFF;
header[4] = start_register >> 8 & 0xFF;
@@ -2460,7 +2466,9 @@ int sdw_cdns_prepare_read_dma_buffer(u8 dev_num, struct sdw_bpt_section *sec, in
}

if (data_size) {
- header[1] = data_size;
+ header[0] &= ~BIT(0);
+ header[0] |= (data_size >> 8) & BIT(0);
+ header[1] = data_size & 0xFF;
header[2] = start_register >> 24 & 0xFF;
header[3] = start_register >> 16 & 0xFF;
header[4] = start_register >> 8 & 0xFF;
@@ -2483,7 +2491,9 @@ int sdw_cdns_prepare_read_dma_buffer(u8 dev_num, struct sdw_bpt_section *sec, in
/* Add fake frame */
header[0] &= ~GENMASK(7, 6); /* Set inactive flag in BPT/BRA frame heade */
while (fake_size >= data_per_frame) {
- header[1] = data_per_frame;
+ header[0] &= ~BIT(0);
+ header[0] |= (data_per_frame >> 8) & BIT(0);
+ header[1] = data_per_frame & 0xFF;
ret = sdw_cdns_prepare_read_pd0_buffer(header, SDW_CDNS_BRA_HDR, p_dma_buffer,
dma_buffer_size, &dma_data_written,
counter);
@@ -2499,7 +2509,9 @@ int sdw_cdns_prepare_read_dma_buffer(u8 dev_num, struct sdw_bpt_section *sec, in
}

if (fake_size) {
- header[1] = fake_size;
+ header[0] &= ~BIT(0);
+ header[0] |= (fake_size >> 8) & BIT(0);
+ header[1] = fake_size & 0xFF;
ret = sdw_cdns_prepare_read_pd0_buffer(header, SDW_CDNS_BRA_HDR, p_dma_buffer,
dma_buffer_size, &dma_data_written,
counter);
--
2.43.0