Re: [PATCH 3/6] Bluetooth: LE scan infra-structure

[Marcel Holtmann <marcel@holtmann.org>]

Hi Andre,

> This patch adds to hci_core the infra-structure to carry out the
> LE scan. Functions were created to init the LE scan and cancel
> an ongoing scanning (hci_do_le_scan and hci_cancel_le_scan).
> 
> Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
> ---
>  include/net/bluetooth/hci_core.h |    5 +++
>  net/bluetooth/hci_core.c         |   69 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 74 insertions(+), 0 deletions(-)
> 
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index f6d5d90..69dda9b 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -232,6 +232,8 @@ struct hci_dev {
>  	struct list_head	adv_entries;
>  	struct timer_list	adv_timer;
>  
> +	struct timer_list	le_scan_timer;
> +
>  	struct hci_dev_stats	stat;
>  
>  	struct sk_buff_head	driver_init;
> @@ -987,5 +989,8 @@ void hci_le_ltk_neg_reply(struct hci_conn *conn);
>  
>  int hci_do_inquiry(struct hci_dev *hdev, u8 length);
>  int hci_cancel_inquiry(struct hci_dev *hdev);
> +int hci_do_le_scan(struct hci_dev *hdev, u8 type, u16 interval, u16 window,
> +								int timeout);
> +int hci_cancel_le_scan(struct hci_dev *hdev);
>  
>  #endif /* __HCI_CORE_H */
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index 64cdafe..c07dc15 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -1423,6 +1423,23 @@ int hci_add_adv_entry(struct hci_dev *hdev,
>  	return 0;
>  }
>  
> +static int le_scan(struct hci_dev *hdev, u8 enable)
> +{
> +	struct hci_cp_le_set_scan_enable cp;
> +
> +	memset(&cp, 0, sizeof(cp));
> +	cp.enable = enable;
> +
> +	return hci_send_cmd(hdev, HCI_OP_LE_SET_SCAN_ENABLE, sizeof(cp), &cp);
> +}
> +
> +static void le_scan_timeout(unsigned long arg)
> +{
> +	struct hci_dev *hdev = (void *) arg;
> +
> +	le_scan(hdev, 0);
> +}
> +
>  /* Register HCI device */
>  int hci_register_dev(struct hci_dev *hdev)
>  {
> @@ -1501,6 +1518,9 @@ int hci_register_dev(struct hci_dev *hdev)
>  	setup_timer(&hdev->adv_timer, hci_clear_adv_cache,
>  						(unsigned long) hdev);
>  
> +	setup_timer(&hdev->le_scan_timer, le_scan_timeout,
> +						(unsigned long) hdev);
> +
>  	INIT_WORK(&hdev->power_on, hci_power_on);
>  	INIT_DELAYED_WORK(&hdev->power_off, hci_power_off);
>  
> @@ -1587,6 +1607,7 @@ void hci_unregister_dev(struct hci_dev *hdev)
>  	hci_del_sysfs(hdev);
>  
>  	del_timer(&hdev->adv_timer);
> +	del_timer(&hdev->le_scan_timer);
>  
>  	destroy_workqueue(hdev->workqueue);
>  
> @@ -2615,3 +2636,51 @@ int hci_cancel_inquiry(struct hci_dev *hdev)
>  
>  	return hci_send_cmd(hdev, HCI_OP_INQUIRY_CANCEL, 0, NULL);
>  }
> +
> +static int set_le_scan_param(struct hci_dev *hdev, u8 type, u16 interval,
> +								u16 window)
> +{
> +	struct hci_cp_le_set_scan_param cp;
> +
> +	memset(&cp, 0, sizeof(cp));
> +	cp.type = type;
> +	cp.interval = cpu_to_le16(interval);
> +	cp.window = cpu_to_le16(window);
> +
> +	return hci_send_cmd(hdev, HCI_OP_LE_SET_SCAN_PARAM, sizeof(cp), &cp);
> +}
> +
> +int hci_do_le_scan(struct hci_dev *hdev, u8 type, u16 interval, u16 window,
> +								int timeout)
> +{
> +	int err;
> +
> +	if (test_bit(HCI_LE_SCAN, &hdev->hci_flags))
> +		return -EINPROGRESS;
> +
> +	BT_DBG("%s", hdev->name);
> +
> +	err = set_le_scan_param(hdev, type, interval, window);
> +	if (err < 0)
> +		return err;
> +
> +	err = le_scan(hdev, 1);
> +	if (err < 0)
> +		return err;

since you are using hci_send_cmd, you never check the error from the
controller for set_le_scan_param. We should be doing exactly that before
just going ahead with a scan.

It is also not guaranteed that the controller queues up these commands,
it might just return busy from le_scan() if it can have more than one
outstanding commands (which many controller can do).

Regards

Marcel