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soundwire: use bra if msg size > threshold in sdw_nread/write_no_pm #5811

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soundwire: use bra if msg size > threshold in sdw_nread/write_no_pm #5811

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e928d5c
soundwire: bus: serialize BPT/BRA transfers per bus
ujfalusi May 11, 2026
35eb117
ASoC: Intel: hda-sdw-bpt: return ENXIO if SOF DSP is not first booted
bardliao Jun 9, 2026
861c55b
soundwire: bus: add bra_w/r_threshold
bardliao Jun 11, 2026
4e63a29
soundwire: use bra if msg size > threshold
bardliao Jun 9, 2026
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110 changes: 104 additions & 6 deletions drivers/soundwire/bus.c
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,9 @@
#include "irq.h"
#include "sysfs_local.h"

#define DEFAULT_BRA_WRITE_THRESHOLD 800
#define DEFAULT_BRA_READ_THRESHOLD 400
Comment on lines +16 to +17

static DEFINE_IDA(sdw_bus_ida);

static int sdw_get_id(struct sdw_bus *bus)
Expand Down Expand Up @@ -87,6 +90,8 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
lockdep_register_key(&bus->bus_lock_key);
__mutex_init(&bus->bus_lock, "bus_lock", &bus->bus_lock_key);

mutex_init(&bus->bpt_lock);

INIT_LIST_HEAD(&bus->slaves);
INIT_LIST_HEAD(&bus->m_rt_list);

Expand Down Expand Up @@ -163,6 +168,11 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
bus->params.curr_bank = SDW_BANK0;
bus->params.next_bank = SDW_BANK1;

if (!bus->bra_w_threshold)
bus->bra_w_threshold = DEFAULT_BRA_WRITE_THRESHOLD;
if (!bus->bra_r_threshold)
bus->bra_r_threshold = DEFAULT_BRA_READ_THRESHOLD;
Comment on lines +171 to +174

return 0;
}
EXPORT_SYMBOL(sdw_bus_master_add);
Expand Down Expand Up @@ -439,6 +449,46 @@ static int sdw_ntransfer_no_pm(struct sdw_slave *slave, u32 addr, u8 flags,
return 0;
}

static int sdw_ntransfer_no_pm_bpt(struct sdw_slave *slave, u32 addr, u8 flags,
size_t count, u8 *val)
{
struct sdw_bpt_section sec;
struct sdw_bpt_msg msg;
size_t size;
int retry = 5;
int ret;

msg.sections = 1;
msg.dev_num = slave->dev_num;
msg.flags = flags;
msg.sec = &sec;

while (count) {
size = min_t(size_t, count, SDW_BPT_MSG_MAX_BYTES);

sec.addr = addr;
sec.len = size;
sec.buf = val;

do {
ret = sdw_bpt_send_sync(slave->bus, slave, &msg);
if (ret == -EAGAIN)
msleep(10);
retry--;
} while (ret == -EAGAIN && retry > 0);

if (ret < 0)
return ret;

addr += size;
val += size;
count -= size;
retry = 5;
}

return 0;
}

/**
* sdw_nread_no_pm() - Read "n" contiguous SDW Slave registers with no PM
* @slave: SDW Slave
Expand All @@ -447,10 +497,26 @@ static int sdw_ntransfer_no_pm(struct sdw_slave *slave, u32 addr, u8 flags,
* @val: Buffer for values to be read
*
* Note that if the message crosses a page boundary each page will be
* transferred under a separate invocation of the msg_lock.
* transferred under a separate invocation of the msg_lock if it is not
* transferred via BPT.
*/
int sdw_nread_no_pm(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
{
struct sdw_bus *bus = slave->bus;
int ret;

if (!bus->ops->bpt_send_async || !bus->ops->bpt_wait ||
count < bus->bra_r_threshold)
goto fallback;

ret = sdw_ntransfer_no_pm_bpt(slave, addr, SDW_MSG_FLAG_READ, count, val);
if (!ret)
return 0;
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dev_dbg(&slave->dev,
"BPT read failed for addr %x, count %zu, ret %d fallback to normal read\n",
addr, count, ret);
fallback:
return sdw_ntransfer_no_pm(slave, addr, SDW_MSG_FLAG_READ, count, val);
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}
EXPORT_SYMBOL(sdw_nread_no_pm);
Expand All @@ -463,10 +529,26 @@ EXPORT_SYMBOL(sdw_nread_no_pm);
* @val: Buffer for values to be written
*
* Note that if the message crosses a page boundary each page will be
* transferred under a separate invocation of the msg_lock.
* transferred under a separate invocation of the msg_lock if it is not
* transferred via BPT.
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*/
int sdw_nwrite_no_pm(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val)
{
struct sdw_bus *bus = slave->bus;
int ret;

if (!bus->ops->bpt_send_async || !bus->ops->bpt_wait ||
count < bus->bra_w_threshold)
goto fallback;

ret = sdw_ntransfer_no_pm_bpt(slave, addr, SDW_MSG_FLAG_WRITE, count, (u8 *)val);
if (!ret)
return 0;

dev_dbg(&slave->dev,
"BPT write failed for addr %x, count %zu, ret %d fallback to normal write\n",
addr, count, ret);
fallback:
return sdw_ntransfer_no_pm(slave, addr, SDW_MSG_FLAG_WRITE, count, (u8 *)val);
Comment on lines +551 to 552
}
Comment on lines 535 to 553

@bardliao bardliao Jun 12, 2026

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@charleskeepax @rfvirgil @simontrimmer @shumingfan Will it cause any issue?

EXPORT_SYMBOL(sdw_nwrite_no_pm);
Expand Down Expand Up @@ -604,7 +686,8 @@ EXPORT_SYMBOL(sdw_update);
* This version of the function will take a PM reference to the slave
* device.
* Note that if the message crosses a page boundary each page will be
* transferred under a separate invocation of the msg_lock.
* transferred under a separate invocation of the msg_lock if it is not
* transferred via BPT.
*/
int sdw_nread(struct sdw_slave *slave, u32 addr, size_t count, u8 *val)
{
Expand Down Expand Up @@ -635,7 +718,8 @@ EXPORT_SYMBOL(sdw_nread);
* This version of the function will take a PM reference to the slave
* device.
* Note that if the message crosses a page boundary each page will be
* transferred under a separate invocation of the msg_lock.
* transferred under a separate invocation of the msg_lock if it is not
* transferred via BPT.
*/
int sdw_nwrite(struct sdw_slave *slave, u32 addr, size_t count, const u8 *val)
{
Expand Down Expand Up @@ -2094,6 +2178,7 @@ EXPORT_SYMBOL(sdw_clear_slave_status);
int sdw_bpt_send_async(struct sdw_bus *bus, struct sdw_slave *slave, struct sdw_bpt_msg *msg)
{
int len = 0;
int ret;
int i;
Comment on lines 2178 to 2182

@bardliao bardliao Jun 12, 2026

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We unlock the mutex when sdw_bpt_send_async, too. It should be fine. @ujfalusi What do you think?


for (i = 0; i < msg->sections; i++)
Expand All @@ -2118,13 +2203,26 @@ int sdw_bpt_send_async(struct sdw_bus *bus, struct sdw_slave *slave, struct sdw_
return -EOPNOTSUPP;
}

return bus->ops->bpt_send_async(bus, slave, msg);
/* Serialize BPT/BRA transfers per bus: PDIs and DMA resources are shared */
mutex_lock(&bus->bpt_lock);

ret = bus->ops->bpt_send_async(bus, slave, msg);
if (ret < 0)
mutex_unlock(&bus->bpt_lock);

/* on success the lock is held until sdw_bpt_wait() */
return ret;
}
EXPORT_SYMBOL(sdw_bpt_send_async);

int sdw_bpt_wait(struct sdw_bus *bus, struct sdw_slave *slave, struct sdw_bpt_msg *msg)
{
return bus->ops->bpt_wait(bus, slave, msg);
int ret;

ret = bus->ops->bpt_wait(bus, slave, msg);
mutex_unlock(&bus->bpt_lock);

return ret;
}
Comment on lines +2206 to 2226

@bardliao bardliao Jun 12, 2026

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Same as the previous comment

EXPORT_SYMBOL(sdw_bpt_wait);

Expand Down
7 changes: 7 additions & 0 deletions include/linux/soundwire/sdw.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1028,6 +1028,10 @@ struct sdw_stream_runtime {
* are supported. This flag is populated by drivers after reading
* appropriate firmware (ACPI/DT).
* @lane_used_bandwidth: how much bandwidth in bits per second is used by each lane
* @bra_w_threshold: Message-size threshold (bytes) above which BPT write is used.
* If set to 0, a default is used.
* @bra_r_threshold: Message-size threshold (bytes) above which BPT read is used.
* If set to 0, a default is used.
Comment on lines +1031 to +1034
*/
struct sdw_bus {
struct device *dev;
Expand All @@ -1044,6 +1048,7 @@ struct sdw_bus {
int stream_refcount;
int bpt_stream_refcount;
struct sdw_stream_runtime *bpt_stream;
struct mutex bpt_lock; /* serialize BPT/BRA transfers per bus */
const struct sdw_master_ops *ops;
const struct sdw_master_port_ops *port_ops;
struct sdw_master_prop prop;
Expand All @@ -1063,6 +1068,8 @@ struct sdw_bus {
#endif
bool multi_link;
unsigned int lane_used_bandwidth[SDW_MAX_LANES];
unsigned int bra_w_threshold;
unsigned int bra_r_threshold;
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};

struct sdw_stream_runtime *sdw_alloc_stream(const char *stream_name, enum sdw_stream_type type);
Expand Down
5 changes: 5 additions & 0 deletions sound/soc/sof/intel/hda-sdw-bpt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -273,6 +273,11 @@ int hda_sdw_bpt_open(struct device *dev, int link_id, struct hdac_ext_stream **b
int ret1;
int ret;

if (!sdev->dspless_mode_selected && sdev->first_boot) {
dev_dbg(dev, "SOF FW boot not complete yet\n");
return -ENXIO;
}
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num_channels_tx = DIV_ROUND_UP(tx_dma_bandwidth, BPT_FREQUENCY * 32);

ret = hda_sdw_bpt_dma_prepare(dev, bpt_tx_stream, dmab_tx_bdl, bpt_tx_num_bytes,
Expand Down
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