su, 2025-08-10 kello 09:15 +0200, Paul Menzel kirjoitti:
> Dear Pauli,
>
>
> Thank you for your reply.
>
> Am 09.08.25 um 11:43 schrieb Pauli Virtanen:
>
> > la, 2025-08-09 kello 11:24 +0200, Paul Menzel kirjoitti:
>
> […]
>
> > > Am 09.08.25 um 10:36 schrieb Pauli Virtanen:
> > > > BN == 0x00 in CIS Established means no isochronous data for the
> > > > corresponding direction (Core v6.1 pp. 2394). In this case SDU MTU
> > > > should be 0.
> > > >
> > > > However, the specification does not say the Max_PDU_C_To_P or P_To_C are
> > > > then zero. Intel AX210 in Framed CIS mode sets nonzero Max_PDU for
> > > > direction with zero BN. This causes failure later when we try to LE
> > > > Setup ISO Data Path for disabled direction, which is disallowed (Core
> > > > v6.1 pp. 2750).
> > > >
> > > > Fix by setting SDU MTU to 0 if BN == 0.
> > >
> > > Do you have command how to reproduce this on the device?
> >
> > As noted in the text above, try to create framed unidirectional CIS on
> > this particular controller, e.g. for 44.1kHz audio.
>
> Indeed, I read that. But I have no idea how to do that. Is that possible
> with the tools, or does this need to be coded explicitly?
This should always happen if you try to create a 44.1 kHz
unidirectional audio stream (they are always framed).
You can do this in Pipewire(master) + BlueZ(master) <-> Pipewire+BlueZ
configuration for example, you'll need to make it use the 44.1kHz in
config or just edit bap-codec-lc3.c
Or, you can do it with bluetoothctl, don't remember the exact syntax
now.
> > > > Fixes: 2be22f1941d5f ("Bluetooth: hci_event: Fix parsing of CIS Established Event")
> > > > Signed-off-by: Pauli Virtanen <pav@xxxxxx>
> > > > ---
> > > > net/bluetooth/hci_event.c | 8 ++++----
> > > > 1 file changed, 4 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > > > index 4f0a6116291e..fe7cdd67ad2a 100644
> > > > --- a/net/bluetooth/hci_event.c
> > > > +++ b/net/bluetooth/hci_event.c
> > > > @@ -6745,8 +6745,8 @@ static void hci_le_cis_established_evt(struct hci_dev *hdev, void *data,
> > > > qos->ucast.out.latency =
> > > > DIV_ROUND_CLOSEST(get_unaligned_le24(ev->p_latency),
> > > > 1000);
> > > > - qos->ucast.in.sdu = le16_to_cpu(ev->c_mtu);
> > > > - qos->ucast.out.sdu = le16_to_cpu(ev->p_mtu);
> > > > + qos->ucast.in.sdu = ev->c_bn ? le16_to_cpu(ev->c_mtu) : 0;
> > > > + qos->ucast.out.sdu = ev->p_bn ? le16_to_cpu(ev->p_mtu) : 0;
> > > > qos->ucast.in.phy = ev->c_phy;
> > > > qos->ucast.out.phy = ev->p_phy;
> > > > break;
> > > > @@ -6760,8 +6760,8 @@ static void hci_le_cis_established_evt(struct hci_dev *hdev, void *data,
> > > > qos->ucast.in.latency =
> > > > DIV_ROUND_CLOSEST(get_unaligned_le24(ev->p_latency),
> > > > 1000);
> > > > - qos->ucast.out.sdu = le16_to_cpu(ev->c_mtu);
> > > > - qos->ucast.in.sdu = le16_to_cpu(ev->p_mtu);
> > > > + qos->ucast.out.sdu = ev->c_bn ? le16_to_cpu(ev->c_mtu) : 0;
> > > > + qos->ucast.in.sdu = ev->p_bn ? le16_to_cpu(ev->p_mtu) : 0;
> > > > qos->ucast.out.phy = ev->c_phy;
> > > > qos->ucast.in.phy = ev->p_phy;
> > > > break;
> > >
> > > Reviewed-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
>
> Kind regards,
>
> Paul
--
Pauli Virtanen
