Hi Marcel,
* Marcel Holtmann <marcel@xxxxxxxxxxxx> [2013-06-13 12:48:51 +0200]:
> Hi Gustavo,
>
> >>> Even though the HCI_Delete_Stored_Link_Key command is mandatory for 1.1
> >>> and later controllers some controllers do not seem to support it
> >>> properly as was witnessed by one Broadcom based controller:
> >>>
> >>> < HCI Command: Delete Stored Link Key (0x03|0x0012) plen 7
> >>> bdaddr 00:00:00:00:00:00 all 1
> >>>> HCI Event: Command Complete (0x0e) plen 4
> >>> Delete Stored Link Key (0x03|0x0012) ncmd 1
> >>> status 0x11 deleted 0
> >>> Error: Unsupported Feature or Parameter Value
> >>>
> >>> Luckily this same controller also doesn't list the command in its
> >>> supported commands bit mask (counting from 0 bit 7 of octet 6):
> >>>
> >>> < HCI Command: Read Local Supported Commands (0x04|0x0002) plen 0
> >>>> HCI Event: Command Complete (0x0e) plen 68
> >>> Read Local Supported Commands (0x04|0x0002) ncmd 1
> >>> status 0x00
> >>> Commands: ffffffffffff1ffffffffffff30fffff3f
> >>>
> >>> Therefore, it makes sense to move sending of HCI_Delete_Stored_Link_Key
> >>> to after receiving the supported commands response and to only send it
> >>> if its respective bit in the mask is set. The downside of this is that
> >>> we no longer send the HCI_Delete_Stored_Link_Key command for Bluetooth
> >>> 1.1 controllers since HCI_Read_Local_Supported_Command was introduced in
> >>> version 1.2, but this is an acceptable penalty as the command in
> >>> question shouldn't affect critical behavior.
> >>>
> >>> Reported-by: Pavel Machek <pavel@xxxxxx>
> >>> Signed-off-by: Johan Hedberg <johan.hedberg@xxxxxxxxx>
> >>> ---
> >>> net/bluetooth/hci_core.c | 14 +++++++++-----
> >>> 1 file changed, 9 insertions(+), 5 deletions(-)
> >>>
> >>> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> >>> index d817c93..d68425c 100644
> >>> --- a/net/bluetooth/hci_core.c
> >>> +++ b/net/bluetooth/hci_core.c
> >>> @@ -341,7 +341,6 @@ static void hci_init1_req(struct hci_request *req, unsigned long opt)
> >>>
> >>> static void bredr_setup(struct hci_request *req)
> >>> {
> >>> - struct hci_cp_delete_stored_link_key cp;
> >>> __le16 param;
> >>> __u8 flt_type;
> >>>
> >>> @@ -365,10 +364,6 @@ static void bredr_setup(struct hci_request *req)
> >>> param = __constant_cpu_to_le16(0x7d00);
> >>> hci_req_add(req, HCI_OP_WRITE_CA_TIMEOUT, 2, ¶m);
> >>>
> >>> - bacpy(&cp.bdaddr, BDADDR_ANY);
> >>> - cp.delete_all = 0x01;
> >>> - hci_req_add(req, HCI_OP_DELETE_STORED_LINK_KEY, sizeof(cp), &cp);
> >>> -
> >>> /* Read page scan parameters */
> >>> if (req->hdev->hci_ver > BLUETOOTH_VER_1_1) {
> >>> hci_req_add(req, HCI_OP_READ_PAGE_SCAN_ACTIVITY, 0, NULL);
> >>> @@ -602,6 +597,15 @@ static void hci_init3_req(struct hci_request *req, unsigned long opt)
> >>> struct hci_dev *hdev = req->hdev;
> >>> u8 p;
> >>
> >> I would have added here a comment to explain what bit we are checking for.
> >
> > I just added:
> >
> > /* Only send HCI_Delete_Stored_Link_Key if it is supported */
>
> that is the super cheap way out. There is no harm in going into details.
>
> /* Some Broadcom based Bluetooth controllers do not support the
> * Delete Stored Link Key command. They are clearly indicating its
> * absence in the bit mask of supported commands.
> *
> * Check the supported commands and only if the the command is marked as
> * supported send it. If not supported assume that the controller does not
> * have actual support for stored link keys which makes this command
> * redundant anyway.
> */
Too late, I just sent out the pull request, I'll queue a patch here just to
add this comment and apply it once this lands on bluetooth-next.
Gustavo
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