Hi Alain, > This patch tolerates connection parameters that were valid before > ESR08_v1.0.0 which was also incoporated into the 4.2 core specification. > > In particular, this addresses compatibility issues with the Lenovo Yoga > Mouse that sees its connection parameters rejected by the max_latency > computation in hci_conn_check_params, but was perfectly valid at the > time this mouse was qualified. > > Before the patch, the mouse was extremely laggy, after the patch, the > mouse worked as expected. > > Signed-off-by: Alain Michaud <alainm@xxxxxxxxxxxx> > Reviewed-by: Miao-chen Chou <mcchou@xxxxxxxxxxxx> > Tested-by: Harry Cutts <hcutts@xxxxxxxxxxxx> > > --- > > include/net/bluetooth/hci_core.h | 30 ++++++++++++++++++++++++++++++ > net/bluetooth/l2cap_core.c | 12 ++++++++++++ > 2 files changed, 42 insertions(+) > > diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h > index ebdd4afe30d2..67b75077c82e 100644 > --- a/include/net/bluetooth/hci_core.h > +++ b/include/net/bluetooth/hci_core.h > @@ -1646,6 +1646,36 @@ static inline struct smp_irk *hci_get_irk(struct hci_dev *hdev, > return hci_find_irk_by_rpa(hdev, bdaddr); > } > > +/* Erratum 5412 which has been fixed in 4.2 changed the validation of > + * connection parameters. For backwards compatibility reasons, the old > + * calculation must be tolerated. > + * For further details : > + * https://www.bluetooth.org/errata/errata_view.cfm?errata_id=5419 > + */ > +static inline int hci_check_conn_params_legacy(u16 min, u16 max, u16 latency, > + u16 to_multiplier) I would not bother with “inline” here. Let the compiler decide. > +{ > + u16 max_latency; > + > + if (min > max || min < 6 || max > 3200) > + return -EINVAL; > + > + if (to_multiplier < 10 || to_multiplier > 3200) > + return -EINVAL; > + > + if (max >= to_multiplier * 8) > + return -EINVAL; > + > + max_latency = (to_multiplier * 8 / max) - 1; > + if (latency > 499 || latency > max_latency) > + return -EINVAL; > + > + return 0; > +} > + > +/* Connection Parameter Validation Helper. > + * See Vol 6, Part B, section 4.5.1. > + */ > static inline int hci_check_conn_params(u16 min, u16 max, u16 latency, > u16 to_multiplier) > { > diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c > index 72c2f5226d67..726e78bd85ff 100644 > --- a/net/bluetooth/l2cap_core.c > +++ b/net/bluetooth/l2cap_core.c > @@ -5553,6 +5553,18 @@ 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) { > + BT_WARN("Invalid conn params min 0x%4.4x max 0x%4.4x latency: 0x%4.4x TO: 0x%4.4x", > + min, max, latency, to_multiplier); Can we use bt_dev_warn() here? > + > + err = hci_check_conn_params_legacy(min, max, latency, > + to_multiplier); > + if (!err) { > + /* latency is invalid, cap it to the max allowed */ > + latency = min(499, (to_multiplier * 4 / max) - 1); > + } > + } > + > if (err) > rsp.result = cpu_to_le16(L2CAP_CONN_PARAM_REJECTED); > else Regards Marcel
