Re: [RFC PATCH] Bluetooth: l2cap: honor local LE connection interval range

[cochcoder]

Thanks for pointing this out. I looked at the git history and confirmed the interoperability problem. I've sent a RFC v2 as 20261015043336.47734-1-cochcoder@xxxxxxxxx. It prefers a valid overlap but preserves the original valid peer request when there is no usable overlap, rather than rejecting it. The native controls cover overlap, fast HID, slow idle and exact-match requests. The strict-bound version rejects the HID and idle cases. The revised full L2CAP suite passes 115/115.



On Tuesday, October 13th, 2026 at 10:33 AM, Luiz Augusto von Dentz <luiz.dentz@xxxxxxxxx> wrote:

> Hi Kyle,
>
> On Mon, Oct 12, 2026 at 11:31 PM Kyle Pepper <cochcoder@xxxxxxxxx> wrote:
> >
> > Intersect a valid peer request with the locally configured interval
> > range. Reject disjoint ranges and preserve validation of the original
> > request before applying local policy.
> >
> > Assisted-by: OpenCode:gpt-6.1-sol
> > Signed-off-by: Kyle Pepper <cochcoder@xxxxxxxxx>
> > ---
> > Submission review notes (not part of the commit message):
> > October 12 no-intersection trial accepts [16,24] and completes 30 ms
> > with STATUS 03 02 18 and normal host TX; the user hears silence. Volume
> > and multi-day acoustic comparison controls are incomplete. The working
> > intersection yields 20 ms. Maximum-only rejection failed in kernel 5
> > and is not this proposal. Generic minimum/range policy and LL-path
> > consistency remain RFC questions, not established by one renderer.
>
> I need to check the git history but I believe we tried something
> similar not long ago that created interoperability problems if we use
> strict range matching like this.
>
> >  net/bluetooth/l2cap_core.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
> > index 49a998804..49e201d3e 100644
> > --- a/net/bluetooth/l2cap_core.c
> > +++ b/net/bluetooth/l2cap_core.c
> > @@ -4968,6 +4968,13 @@ static inline int l2cap_conn_param_update_req(struct l2cap_conn *conn,
> >         memset(&rsp, 0, sizeof(rsp));
> >
> >         err = hci_check_conn_params(min, max, latency, to_multiplier);
> > +       if (!err) {
> > +               /* Apply local policy only after validating the peer's request. */
> > +               min = max_t(u16, min, hcon->le_conn_min_interval);
> > +               max = min_t(u16, max, hcon->le_conn_max_interval);
> > +               err = hci_check_conn_params(min, max, latency, to_multiplier);
> > +       }
> > +
> >         if (err)
> >                 rsp.result = cpu_to_le16(L2CAP_CONN_PARAM_REJECTED);
> >         else
> >
> > base-commit: 964430c038967fd06643e866f68115664e1a1bd1
> >
>
>
> --
> Luiz Augusto von Dentz
>