Hi,
[ EXTERNAL EMAIL ]
Hi,
ke, 2025-07-02 kello 19:35 +0800, Yang Li via B4 Relay kirjoitti:
From: Yang Li <yang.li@xxxxxxxxxxx>
User-space applications (e.g., PipeWire) depend on
ISO-formatted timestamps for precise audio sync.
Signed-off-by: Yang Li <yang.li@xxxxxxxxxxx>
---
Changes in v2:
- Support SOCK_RCVTSTAMPNS via CMSG for ISO sockets
- Link to v1: https://lore.kernel.org/r/20250429-iso_ts-v1-1-e586f30de6cb@xxxxxxxxxxx
---
net/bluetooth/iso.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index fc22782cbeeb..6927c593a1d6 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -2308,6 +2308,9 @@ void iso_recv(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
goto drop;
}
+ /* Record the timestamp to skb*/
+ skb->skb_mstamp_ns = le32_to_cpu(hdr->ts);
Hardware timestamps are supposed to go in
skb_hwtstamps(skb)->hwtstamp
See Documentation/networking/timestamping.rst
"3.1 Hardware Timestamping Implementation: Device Drivers" and how it
is done in drivers/net/
This documentation also explains how user applications can obtain the
hardware timestamps.
AFAIK, skb->tstamp (skb->skb_mstamp_ns is union for it) must be in
system clock. The hdr->ts is in some unsynchronized controller clock,
so they should go to HW timestamps.
Following your suggestion, I switched to hwtstamp but kept
SO_TIMESTAMPNS on the PipeWire side.
+ struct skb_shared_hwtstamps *hwts =
skb_hwtstamps(skb);
+ if (hwts)
+ hwts->hwtstamp =
us_to_ktime(le32_to_cpu(hdr->ts));
+
The value I get is unexpectedly large and not the same as the timestamp
in the ISO data.
read_data: received timestamp: 880608.479272966
read_data: received timestamp: 880608.479438633
read_data: received timestamp: 880608.489259466
read_data: received timestamp: 880608.489434550
read_data: received timestamp: 880608.499289258
read_data: received timestamp: 880608.499464550
read_data: received timestamp: 880608.509278008
read_data: received timestamp: 880608.509451425
read_data: received timestamp: 880608.519261175
read_data: received timestamp: 880608.519438633
read_data: received timestamp: 880608.529385008
read_data: received timestamp: 880608.529462133
read_data: received timestamp: 880608.539273758
read_data: received timestamp: 880608.539452758
read_data: received timestamp: 880608.549271258
read_data: received timestamp: 880608.549450008
read_data: received timestamp: 880608.559263466
read_data: received timestamp: 880608.559443216
read_data: received timestamp: 880608.569257466
Is there any special processing in the application code?
+
len = __le16_to_cpu(hdr->slen);
} else {
struct hci_iso_data_hdr *hdr;
---
base-commit: 3bc46213b81278f3a9df0324768e152de71eb9fe
change-id: 20250421-iso_ts-c82a300ae784
Best regards,
--
Pauli Virtanen
