Hi Jason,
[ EXTERNAL EMAIL ]
Hi Yang,
On Fri, Jul 4, 2025 at 1:36 PM Yang Li via B4 Relay
<devnull+yang.li.amlogic.com@xxxxxxxxxx> wrote:
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 v3:
- Change to use hwtimestamp
- Link to v2: https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@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 | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index fc22782cbeeb..67ff355167d8 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -2301,13 +2301,21 @@ void iso_recv(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
if (ts) {
struct hci_iso_ts_data_hdr *hdr;
- /* TODO: add timestamp to the packet? */
hdr = skb_pull_data(skb, HCI_ISO_TS_DATA_HDR_SIZE);
if (!hdr) {
BT_ERR("Frame is too short (len %d)", skb->len);
goto drop;
}
+ /* The ISO ts is based on the controller’s clock domain,
+ * so hardware timestamping (hwtimestamp) must be used.
+ * Ref: Documentation/networking/timestamping.rst,
+ * chapter 3.1 Hardware Timestamping.
+ */
I think the above comment is not necessary as it's a common usage for
all kinds of drivers. If you reckon the information could be helpful,
then you could clarify it in the commit message :)
Okay, I got it.
+ struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);
The above line should be moved underneath the 'if (ts) {' line because
we need to group all the declarations altogether at the beginning.
Yes, I will do.
+ if (hwts)
+ hwts->hwtstamp = us_to_ktime(le32_to_cpu(hdr->ts));
+
I'm definitely not a bluetooth expert, so I'm here only to check the
timestamping usage. According to your prior v2 patch, the
reader/receiver to turn on the timestamping feature is implemented in
PipeWire? If so, so far the kernel part looks good to me.
Yes, please reference reply:
https://lore.kernel.org/all/df9f6977-0d63-41b3-8d9b-c3a293ed78ec@xxxxxxxxxxx/
Thanks,
Jason
