[PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[Yang Li via B4 Relay]

From: Yang Li <yang.li@amlogic.com>

User-space applications (e.g., PipeWire) depend on
ISO-formatted timestamps for precise audio sync.

Signed-off-by: Yang Li <yang.li@amlogic.com>
---
Changes in v3:
- Change to use hwtimestamp
- Link to v2: https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@amlogic.com

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@amlogic.com
---
 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.
+ 			 */
+			struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);
+			if (hwts)
+				hwts->hwtstamp = us_to_ktime(le32_to_cpu(hdr->ts));
+
 			len = __le16_to_cpu(hdr->slen);
 		} else {
 			struct hci_iso_data_hdr *hdr;

---
base-commit: 3bc46213b81278f3a9df0324768e152de71eb9fe
change-id: 20250421-iso_ts-c82a300ae784

Best regards,
-- 
Yang Li <yang.li@amlogic.com>

Re: [PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[Bastien Nocera]

On Fri, 2025-07-04 at 13:36 +0800, Yang Li via B4 Relay wrote:
> From: Yang Li <yang.li@amlogic.com>
> 
> User-space applications (e.g., PipeWire) depend on
> ISO-formatted timestamps for precise audio sync.
> 
> Signed-off-by: Yang Li <yang.li@amlogic.com>
> ---
> Changes in v3:
> - Change to use hwtimestamp
> - Link to v2:
> https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@amlogic.com
> 
> 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@amlogic.com
> ---
>  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.
> + 			 */
> +			struct skb_shared_hwtstamps *hwts =
> skb_hwtstamps(skb);

The variable should be declared at the top of the scope.

Cheers

> +			if (hwts)
> +				hwts->hwtstamp =
> us_to_ktime(le32_to_cpu(hdr->ts));
> +
>  			len = __le16_to_cpu(hdr->slen);
>  		} else {
>  			struct hci_iso_data_hdr *hdr;
> 
> ---
> base-commit: 3bc46213b81278f3a9df0324768e152de71eb9fe
> change-id: 20250421-iso_ts-c82a300ae784
> 
> Best regards,

Re: [PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[Jason Xing]

Hi Yang,

On Fri, Jul 4, 2025 at 1:36 PM Yang Li via B4 Relay
<devnull+yang.li.amlogic.com@kernel.org> wrote:
>
> From: Yang Li <yang.li@amlogic.com>
>
> User-space applications (e.g., PipeWire) depend on
> ISO-formatted timestamps for precise audio sync.
>
> Signed-off-by: Yang Li <yang.li@amlogic.com>
> ---
> Changes in v3:
> - Change to use hwtimestamp
> - Link to v2: https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@amlogic.com
>
> 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@amlogic.com
> ---
>  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 :)

> +                       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.

> +                       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.

Thanks,
Jason

Re: [PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[Pauli Virtanen]

Hi,

pe, 2025-07-04 kello 13:36 +0800, Yang Li via B4 Relay kirjoitti:
> From: Yang Li <yang.li@amlogic.com>
> 
> User-space applications (e.g., PipeWire) depend on
> ISO-formatted timestamps for precise audio sync.
> 
> Signed-off-by: Yang Li <yang.li@amlogic.com>
> ---
> Changes in v3:
> - Change to use hwtimestamp
> - Link to v2: https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@amlogic.com
> 
> 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@amlogic.com
> ---
>  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.
> + 			 */
> +			struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);
> +			if (hwts)

In addition to the moving variable on top, the null check is spurious
as skb_hwtstamps is never NULL (driver/net/* do not check it either).

Did you test this with SOF_TIMESTAMPING_RX_HARDWARE in userspace?
Pipewire does not try to get HW timestamps right now.

Would be good to also add some tests in bluez/tools/iso-tester.c
although this needs some extension to the emulator/* to support
timestamps properly.

> +				hwts->hwtstamp = us_to_ktime(le32_to_cpu(hdr->ts));
> +
>  			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

Re: [PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[Yang Li]

Hi,
> [ EXTERNAL EMAIL ]
>
> On Fri, 2025-07-04 at 13:36 +0800, Yang Li via B4 Relay wrote:
>> From: Yang Li <yang.li@amlogic.com>
>>
>> User-space applications (e.g., PipeWire) depend on
>> ISO-formatted timestamps for precise audio sync.
>>
>> Signed-off-by: Yang Li <yang.li@amlogic.com>
>> ---
>> Changes in v3:
>> - Change to use hwtimestamp
>> - Link to v2:
>> https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@amlogic.com
>>
>> 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@amlogic.com
>> ---
>>   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.
>> +                      */
>> +                     struct skb_shared_hwtstamps *hwts =
>> skb_hwtstamps(skb);
> The variable should be declared at the top of the scope.
>
> Cheers


Will do.

>> +                     if (hwts)
>> +                             hwts->hwtstamp =
>> us_to_ktime(le32_to_cpu(hdr->ts));
>> +
>>                        len = __le16_to_cpu(hdr->slen);
>>                } else {
>>                        struct hci_iso_data_hdr *hdr;
>>
>> ---
>> base-commit: 3bc46213b81278f3a9df0324768e152de71eb9fe
>> change-id: 20250421-iso_ts-c82a300ae784
>>
>> Best regards,

Re: [PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[Yang Li]

Hi,
> [ EXTERNAL EMAIL ]
>
> Hi,
>
> pe, 2025-07-04 kello 13:36 +0800, Yang Li via B4 Relay kirjoitti:
>> From: Yang Li <yang.li@amlogic.com>
>>
>> User-space applications (e.g., PipeWire) depend on
>> ISO-formatted timestamps for precise audio sync.
>>
>> Signed-off-by: Yang Li <yang.li@amlogic.com>
>> ---
>> Changes in v3:
>> - Change to use hwtimestamp
>> - Link to v2: https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@amlogic.com
>>
>> 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@amlogic.com
>> ---
>>   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.
>> +                      */
>> +                     struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);
>> +                     if (hwts)
> In addition to the moving variable on top, the null check is spurious
> as skb_hwtstamps is never NULL (driver/net/* do not check it either).
>
> Did you test this with SOF_TIMESTAMPING_RX_HARDWARE in userspace?
> Pipewire does not try to get HW timestamps right now.
>
> Would be good to also add some tests in bluez/tools/iso-tester.c
> although this needs some extension to the emulator/* to support
> timestamps properly.


Yes, here is the patch and log based on testing with Pipewire:

diff --git a/spa/plugins/bluez5/media-source.c 
b/spa/plugins/bluez5/media-source.c
index 2fe08b8..10e9378 100644
--- a/spa/plugins/bluez5/media-source.c
+++ b/spa/plugins/bluez5/media-source.c
@@ -407,7 +413,7 @@ static int32_t read_data(struct impl *this) {
         struct msghdr msg = {0};
         struct iovec iov;
         char control[128];
-       struct timespec *ts = NULL;
+       struct scm_timestamping *ts = NULL;

         iov.iov_base = this->buffer_read;
         iov.iov_len = b_size;
@@ -439,12 +445,14 @@ again:
         struct cmsghdr *cmsg;
         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = 
CMSG_NXTHDR(&msg, cmsg)) {
  #ifdef SCM_TIMESTAMPING
                 /* Check for timestamp */
+               if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == 
SCM_TIMESTAMPING) {
+                       ts = (struct scm_timestamping *)CMSG_DATA(cmsg);
+                       spa_log_error(this->log, "%p: received timestamp 
%ld.%09ld",
+                                       this, ts->ts[2].tv_sec, 
ts->ts[2].tv_nsec);
                         break;
                 }
  #endif

  @@ -726,9 +734,9 @@ static int transport_start(struct impl *this)
         if (setsockopt(this->fd, SOL_SOCKET, SO_PRIORITY, &val, 
sizeof(val)) < 0)
                 spa_log_warn(this->log, "SO_PRIORITY failed: %m");

+       val = SOF_TIMESTAMPING_RX_HARDWARE | SOF_TIMESTAMPING_RAW_HARDWARE;
+       if (setsockopt(this->fd, SOL_SOCKET, SO_TIMESTAMPING, &val, 
sizeof(val)) < 0) {
+               spa_log_warn(this->log, "SO_TIMESTAMPING failed: %m");
                 /* don't fail if timestamping is not supported */
         }

trace log：

read_data: 0x1e78d68: received timestamp 7681.972000000
read_data: 0x1e95000: received timestamp 7681.972000000
read_data: 0x1e78d68: received timestamp 7691.972000000
read_data: 0x1e95000: received timestamp 7691.972000000
read_data: 0x1e78d68: received timestamp 7701.972000000
read_data: 0x1e95000: received timestamp 7701.972000000
read_data: 0x1e78d68: received timestamp 7711.972000000
read_data: 0x1e95000: received timestamp 7711.972000000
read_data: 0x1e78d68: received timestamp 7721.972000000
read_data: 0x1e95000: received timestamp 7721.972000000
read_data: 0x1e78d68: received timestamp 7731.972000000

>
>> +                             hwts->hwtstamp = us_to_ktime(le32_to_cpu(hdr->ts));
>> +
>>                        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

Re: [PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[Yang Li]

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@kernel.org> wrote:
>> From: Yang Li <yang.li@amlogic.com>
>>
>> User-space applications (e.g., PipeWire) depend on
>> ISO-formatted timestamps for precise audio sync.
>>
>> Signed-off-by: Yang Li <yang.li@amlogic.com>
>> ---
>> Changes in v3:
>> - Change to use hwtimestamp
>> - Link to v2: https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@amlogic.com
>>
>> 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@amlogic.com
>> ---
>>   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@amlogic.com/


>
> Thanks,
> Jason

Re: [PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[Pauli Virtanen]

Hi,

ma, 2025-07-07 kello 09:48 +0800, Yang Li kirjoitti:
> Hi,
> > [ EXTERNAL EMAIL ]
> > 
> > Hi,
> > 
> > pe, 2025-07-04 kello 13:36 +0800, Yang Li via B4 Relay kirjoitti:
> > > From: Yang Li <yang.li@amlogic.com>
> > > 
> > > User-space applications (e.g., PipeWire) depend on
> > > ISO-formatted timestamps for precise audio sync.
> > > 
> > > Signed-off-by: Yang Li <yang.li@amlogic.com>
> > > ---
> > > Changes in v3:
> > > - Change to use hwtimestamp
> > > - Link to v2: https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@amlogic.com
> > > 
> > > 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@amlogic.com
> > > ---
> > >   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.
> > > +                      */
> > > +                     struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);
> > > +                     if (hwts)
> > In addition to the moving variable on top, the null check is spurious
> > as skb_hwtstamps is never NULL (driver/net/* do not check it either).
> > 
> > Did you test this with SOF_TIMESTAMPING_RX_HARDWARE in userspace?
> > Pipewire does not try to get HW timestamps right now.
> > 
> > Would be good to also add some tests in bluez/tools/iso-tester.c
> > although this needs some extension to the emulator/* to support
> > timestamps properly.
> 
> 
> Yes, here is the patch and log based on testing with Pipewire:
> 
> diff --git a/spa/plugins/bluez5/media-source.c 
> b/spa/plugins/bluez5/media-source.c
> index 2fe08b8..10e9378 100644
> --- a/spa/plugins/bluez5/media-source.c
> +++ b/spa/plugins/bluez5/media-source.c
> @@ -407,7 +413,7 @@ static int32_t read_data(struct impl *this) {
>          struct msghdr msg = {0};
>          struct iovec iov;
>          char control[128];
> -       struct timespec *ts = NULL;
> +       struct scm_timestamping *ts = NULL;
> 
>          iov.iov_base = this->buffer_read;
>          iov.iov_len = b_size;
> @@ -439,12 +445,14 @@ again:
>          struct cmsghdr *cmsg;
>          for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = 
> CMSG_NXTHDR(&msg, cmsg)) {
>   #ifdef SCM_TIMESTAMPING
>                  /* Check for timestamp */
> +               if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == 
> SCM_TIMESTAMPING) {
> +                       ts = (struct scm_timestamping *)CMSG_DATA(cmsg);
> +                       spa_log_error(this->log, "%p: received timestamp 
> %ld.%09ld",
> +                                       this, ts->ts[2].tv_sec, 
> ts->ts[2].tv_nsec);
>                          break;
>                  }
>   #endif
> 
>   @@ -726,9 +734,9 @@ static int transport_start(struct impl *this)
>          if (setsockopt(this->fd, SOL_SOCKET, SO_PRIORITY, &val, 
> sizeof(val)) < 0)
>                  spa_log_warn(this->log, "SO_PRIORITY failed: %m");
> 
> +       val = SOF_TIMESTAMPING_RX_HARDWARE | SOF_TIMESTAMPING_RAW_HARDWARE;
> +       if (setsockopt(this->fd, SOL_SOCKET, SO_TIMESTAMPING, &val, 
> sizeof(val)) < 0) {
> +               spa_log_warn(this->log, "SO_TIMESTAMPING failed: %m");
>                  /* don't fail if timestamping is not supported */
>          }
> 
> trace log：
> 
> read_data: 0x1e78d68: received timestamp 7681.972000000
> read_data: 0x1e95000: received timestamp 7681.972000000
> read_data: 0x1e78d68: received timestamp 7691.972000000
> read_data: 0x1e95000: received timestamp 7691.972000000

The counter increases by 10 *seconds* on each step. Is there some
scaling problem here, or is the hardware producing bogus values?

Isn't it supposed to increase by ISO interval (10 *milliseconds*)?

> read_data: 0x1e78d68: received timestamp 7701.972000000
> read_data: 0x1e95000: received timestamp 7701.972000000
> read_data: 0x1e78d68: received timestamp 7711.972000000
> read_data: 0x1e95000: received timestamp 7711.972000000
> read_data: 0x1e78d68: received timestamp 7721.972000000
> read_data: 0x1e95000: received timestamp 7721.972000000
> read_data: 0x1e78d68: received timestamp 7731.972000000
> 
> > 
> > > +                             hwts->hwtstamp = us_to_ktime(le32_to_cpu(hdr->ts));
> > > +
> > >                        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

-- 
Pauli Virtanen

Re: [PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[Yang Li]

Hi Pauli,
> [ EXTERNAL EMAIL ]
>
> Hi,
>
> ma, 2025-07-07 kello 09:48 +0800, Yang Li kirjoitti:
>> Hi,
>>> [ EXTERNAL EMAIL ]
>>>
>>> Hi,
>>>
>>> pe, 2025-07-04 kello 13:36 +0800, Yang Li via B4 Relay kirjoitti:
>>>> From: Yang Li <yang.li@amlogic.com>
>>>>
>>>> User-space applications (e.g., PipeWire) depend on
>>>> ISO-formatted timestamps for precise audio sync.
>>>>
>>>> Signed-off-by: Yang Li <yang.li@amlogic.com>
>>>> ---
>>>> Changes in v3:
>>>> - Change to use hwtimestamp
>>>> - Link to v2: https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@amlogic.com
>>>>
>>>> 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@amlogic.com
>>>> ---
>>>>    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.
>>>> +                      */
>>>> +                     struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);
>>>> +                     if (hwts)
>>> In addition to the moving variable on top, the null check is spurious
>>> as skb_hwtstamps is never NULL (driver/net/* do not check it either).
>>>
>>> Did you test this with SOF_TIMESTAMPING_RX_HARDWARE in userspace?
>>> Pipewire does not try to get HW timestamps right now.
>>>
>>> Would be good to also add some tests in bluez/tools/iso-tester.c
>>> although this needs some extension to the emulator/* to support
>>> timestamps properly.
>>
>> Yes, here is the patch and log based on testing with Pipewire:
>>
>> diff --git a/spa/plugins/bluez5/media-source.c
>> b/spa/plugins/bluez5/media-source.c
>> index 2fe08b8..10e9378 100644
>> --- a/spa/plugins/bluez5/media-source.c
>> +++ b/spa/plugins/bluez5/media-source.c
>> @@ -407,7 +413,7 @@ static int32_t read_data(struct impl *this) {
>>           struct msghdr msg = {0};
>>           struct iovec iov;
>>           char control[128];
>> -       struct timespec *ts = NULL;
>> +       struct scm_timestamping *ts = NULL;
>>
>>           iov.iov_base = this->buffer_read;
>>           iov.iov_len = b_size;
>> @@ -439,12 +445,14 @@ again:
>>           struct cmsghdr *cmsg;
>>           for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg =
>> CMSG_NXTHDR(&msg, cmsg)) {
>>    #ifdef SCM_TIMESTAMPING
>>                   /* Check for timestamp */
>> +               if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type ==
>> SCM_TIMESTAMPING) {
>> +                       ts = (struct scm_timestamping *)CMSG_DATA(cmsg);
>> +                       spa_log_error(this->log, "%p: received timestamp
>> %ld.%09ld",
>> +                                       this, ts->ts[2].tv_sec,
>> ts->ts[2].tv_nsec);
>>                           break;
>>                   }
>>    #endif
>>
>>    @@ -726,9 +734,9 @@ static int transport_start(struct impl *this)
>>           if (setsockopt(this->fd, SOL_SOCKET, SO_PRIORITY, &val,
>> sizeof(val)) < 0)
>>                   spa_log_warn(this->log, "SO_PRIORITY failed: %m");
>>
>> +       val = SOF_TIMESTAMPING_RX_HARDWARE | SOF_TIMESTAMPING_RAW_HARDWARE;
>> +       if (setsockopt(this->fd, SOL_SOCKET, SO_TIMESTAMPING, &val,
>> sizeof(val)) < 0) {
>> +               spa_log_warn(this->log, "SO_TIMESTAMPING failed: %m");
>>                   /* don't fail if timestamping is not supported */
>>           }
>>
>> trace log：
>>
>> read_data: 0x1e78d68: received timestamp 7681.972000000
>> read_data: 0x1e95000: received timestamp 7681.972000000
>> read_data: 0x1e78d68: received timestamp 7691.972000000
>> read_data: 0x1e95000: received timestamp 7691.972000000
> The counter increases by 10 *seconds* on each step. Is there some
> scaling problem here, or is the hardware producing bogus values?
>
> Isn't it supposed to increase by ISO interval (10 *milliseconds*)?


Yes, you are right. The interval should be the ISO interval (10 ms).
The 10 s interval in the log happened because the kernel version I 
tested (6.6) doesn’t have us_to_ktime(), so I wrote a custom version, 
but the conversion factor was wrong.
kernel patch as below:

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index 070de5588c74..de05587393fa 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -2251,6 +2251,10 @@ static void iso_disconn_cfm(struct hci_conn 
*hcon, __u8 reason)

         iso_conn_del(hcon, bt_to_errno(reason));
  }
+static  ktime_t us_to_ktime(u64 us)
+{
+       return us * 1000000L;
+}

  void iso_recv(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
  {
@@ -2285,6 +2289,11 @@ void iso_recv(struct hci_conn *hcon, struct 
sk_buff *skb, u16 flags)
                                 goto drop;
                         }

+                       /* Record the timestamp to skb*/
+                       struct skb_shared_hwtstamps *hwts = 
skb_hwtstamps(skb);
+                       if (hwts)
+                               hwts->hwtstamp = 
us_to_ktime(le32_to_cpu(hdr->ts));
+

>
>> read_data: 0x1e78d68: received timestamp 7701.972000000
>> read_data: 0x1e95000: received timestamp 7701.972000000
>> read_data: 0x1e78d68: received timestamp 7711.972000000
>> read_data: 0x1e95000: received timestamp 7711.972000000
>> read_data: 0x1e78d68: received timestamp 7721.972000000
>> read_data: 0x1e95000: received timestamp 7721.972000000
>> read_data: 0x1e78d68: received timestamp 7731.972000000
>>
>>>> +                             hwts->hwtstamp = us_to_ktime(le32_to_cpu(hdr->ts));
>>>> +
>>>>                         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
> --
> Pauli Virtanen

Re: [PATCH v3] Bluetooth: ISO: Support SCM_TIMESTAMPING for ISO TS

[Pauli Virtanen]

Hi,

ma, 2025-07-07 kello 16:18 +0800, Yang Li kirjoitti:
> Hi Pauli,
> > [ EXTERNAL EMAIL ]
> > 
> > Hi,
> > 
> > ma, 2025-07-07 kello 09:48 +0800, Yang Li kirjoitti:
> > > Hi,
> > > > [ EXTERNAL EMAIL ]
> > > > 
> > > > Hi,
> > > > 
> > > > pe, 2025-07-04 kello 13:36 +0800, Yang Li via B4 Relay kirjoitti:
> > > > > From: Yang Li <yang.li@amlogic.com>
> > > > > 
> > > > > User-space applications (e.g., PipeWire) depend on
> > > > > ISO-formatted timestamps for precise audio sync.
> > > > > 
> > > > > Signed-off-by: Yang Li <yang.li@amlogic.com>
> > > > > ---
> > > > > Changes in v3:
> > > > > - Change to use hwtimestamp
> > > > > - Link to v2: https://lore.kernel.org/r/20250702-iso_ts-v2-1-723d199c8068@amlogic.com
> > > > > 
> > > > > 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@amlogic.com
> > > > > ---
> > > > >    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.
> > > > > +                      */
> > > > > +                     struct skb_shared_hwtstamps *hwts = skb_hwtstamps(skb);
> > > > > +                     if (hwts)
> > > > In addition to the moving variable on top, the null check is spurious
> > > > as skb_hwtstamps is never NULL (driver/net/* do not check it either).
> > > > 
> > > > Did you test this with SOF_TIMESTAMPING_RX_HARDWARE in userspace?
> > > > Pipewire does not try to get HW timestamps right now.
> > > > 
> > > > Would be good to also add some tests in bluez/tools/iso-tester.c
> > > > although this needs some extension to the emulator/* to support
> > > > timestamps properly.
> > > 
> > > Yes, here is the patch and log based on testing with Pipewire:
> > > 
> > > diff --git a/spa/plugins/bluez5/media-source.c
> > > b/spa/plugins/bluez5/media-source.c
> > > index 2fe08b8..10e9378 100644
> > > --- a/spa/plugins/bluez5/media-source.c
> > > +++ b/spa/plugins/bluez5/media-source.c
> > > @@ -407,7 +413,7 @@ static int32_t read_data(struct impl *this) {
> > >           struct msghdr msg = {0};
> > >           struct iovec iov;
> > >           char control[128];
> > > -       struct timespec *ts = NULL;
> > > +       struct scm_timestamping *ts = NULL;
> > > 
> > >           iov.iov_base = this->buffer_read;
> > >           iov.iov_len = b_size;
> > > @@ -439,12 +445,14 @@ again:
> > >           struct cmsghdr *cmsg;
> > >           for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg =
> > > CMSG_NXTHDR(&msg, cmsg)) {
> > >    #ifdef SCM_TIMESTAMPING
> > >                   /* Check for timestamp */
> > > +               if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type ==
> > > SCM_TIMESTAMPING) {
> > > +                       ts = (struct scm_timestamping *)CMSG_DATA(cmsg);
> > > +                       spa_log_error(this->log, "%p: received timestamp
> > > %ld.%09ld",
> > > +                                       this, ts->ts[2].tv_sec,
> > > ts->ts[2].tv_nsec);
> > >                           break;
> > >                   }
> > >    #endif
> > > 
> > >    @@ -726,9 +734,9 @@ static int transport_start(struct impl *this)
> > >           if (setsockopt(this->fd, SOL_SOCKET, SO_PRIORITY, &val,
> > > sizeof(val)) < 0)
> > >                   spa_log_warn(this->log, "SO_PRIORITY failed: %m");
> > > 
> > > +       val = SOF_TIMESTAMPING_RX_HARDWARE | SOF_TIMESTAMPING_RAW_HARDWARE;
> > > +       if (setsockopt(this->fd, SOL_SOCKET, SO_TIMESTAMPING, &val,
> > > sizeof(val)) < 0) {
> > > +               spa_log_warn(this->log, "SO_TIMESTAMPING failed: %m");
> > >                   /* don't fail if timestamping is not supported */
> > >           }
> > > 
> > > trace log：
> > > 
> > > read_data: 0x1e78d68: received timestamp 7681.972000000
> > > read_data: 0x1e95000: received timestamp 7681.972000000
> > > read_data: 0x1e78d68: received timestamp 7691.972000000
> > > read_data: 0x1e95000: received timestamp 7691.972000000
> > The counter increases by 10 *seconds* on each step. Is there some
> > scaling problem here, or is the hardware producing bogus values?
> > 
> > Isn't it supposed to increase by ISO interval (10 *milliseconds*)?
> 
> 
> Yes, you are right. The interval should be the ISO interval (10 ms).
> The 10 s interval in the log happened because the kernel version I 
> tested (6.6) doesn’t have us_to_ktime(), so I wrote a custom version, 
> but the conversion factor was wrong.

Ok, then there's no problem.

Regarding the tests, it's probably fairly straightforward to add. Only
thing that would need doing is to add new testcase similar to ""ISO
Receive - RX Timestamping"" in bluez/tools/iso-tester.c with HW
timestamping enabled, and edit bluez/tools/tester.h:rx_timestamp_check
to also check HW timestamps if enabled.

> kernel patch as below:
> 
> diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
> index 070de5588c74..de05587393fa 100644
> --- a/net/bluetooth/iso.c
> +++ b/net/bluetooth/iso.c
> @@ -2251,6 +2251,10 @@ static void iso_disconn_cfm(struct hci_conn 
> *hcon, __u8 reason)
> 
>          iso_conn_del(hcon, bt_to_errno(reason));
>   }
> +static  ktime_t us_to_ktime(u64 us)
> +{
> +       return us * 1000000L;
> +}
> 
>   void iso_recv(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
>   {
> @@ -2285,6 +2289,11 @@ void iso_recv(struct hci_conn *hcon, struct 
> sk_buff *skb, u16 flags)
>                                  goto drop;
>                          }
> 
> +                       /* Record the timestamp to skb*/
> +                       struct skb_shared_hwtstamps *hwts = 
> skb_hwtstamps(skb);
> +                       if (hwts)
> +                               hwts->hwtstamp = 
> us_to_ktime(le32_to_cpu(hdr->ts));
> +
> 
> > 
> > > read_data: 0x1e78d68: received timestamp 7701.972000000
> > > read_data: 0x1e95000: received timestamp 7701.972000000
> > > read_data: 0x1e78d68: received timestamp 7711.972000000
> > > read_data: 0x1e95000: received timestamp 7711.972000000
> > > read_data: 0x1e78d68: received timestamp 7721.972000000
> > > read_data: 0x1e95000: received timestamp 7721.972000000
> > > read_data: 0x1e78d68: received timestamp 7731.972000000
> > > 
> > > > > +                             hwts->hwtstamp = us_to_ktime(le32_to_cpu(hdr->ts));
> > > > > +
> > > > >                         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
> > --
> > Pauli Virtanen

-- 
Pauli Virtanen