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From:   Archie Pusaka <apusaka@google.com>
Date:   Fri, 15 Jan 2021 15:05:19 +0800
Message-ID: <CAJQfnxGgWN6G=NE84KBaVxT1no-j9QuReE6rS6vdP9rZEgZ9Mg@mail.gmail.com>
Subject: Re: [RESEND 1/2] Bluetooth: btusb: Add support for queuing during
 polling interval
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc:     Abhishek Pandit-Subedi <abhishekpandit@chromium.org>,
        Alain Michaud <alainmichaud@google.com>,
        Bluez mailing list <linux-bluetooth@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi Luiz,
I don't think we have tested the second patch yet.

Hi Abhishek,
Do you have context on this?

On Thu, 14 Jan 2021 at 11:57, Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
>
> This makes btusb to queue ACL and events during a polling interval
> by using of a delayed work, with the interval working as a time window
> where frames received from different endpoints are considered to be
> arrived at same time and then attempt to resolve potential conflics by
> processing the events ahead of ACL packets.
>
> It worth noting though that priorizing events over ACL data may result
> in inverting the order compared to how they appeared over the air, for
> instance there may be packets received before a disconnect event that
> will be discarded and unencrypted packets received before encryption
> change which would considered encrypted, because of these potential
> changes on the order the support for queuing during the polling
> interval is not enabled by default so platforms have the following
> means to enable it:
>
> At build-time:
>
>     CONFIG_BT_HCIBTUSB_INTERVAL=y
>
> At runtime with use of module option:
>
>     enable_interval
>
> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

Tested-by: Archie Pusaka <apusaka@chromium.org>

> ---
>  drivers/bluetooth/Kconfig |  7 ++++
>  drivers/bluetooth/btusb.c | 88 ++++++++++++++++++++++++++++++++++-----
>  2 files changed, 84 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig
> index 4e73a531b377..2f20a853d946 100644
> --- a/drivers/bluetooth/Kconfig
> +++ b/drivers/bluetooth/Kconfig
> @@ -41,6 +41,13 @@ config BT_HCIBTUSB_AUTOSUSPEND
>           This can be overridden by passing btusb.enable_autosuspend=[y|n]
>           on the kernel commandline.
>
> +config BT_HCIBTUSB_INTERVAL
> +       bool "Enable notification of USB polling interval"
> +       depends on BT_HCIBTUSB
> +       help
> +         Say Y here to enable notification of USB polling interval for
> +         Bluetooth USB devices by default.
> +
>  config BT_HCIBTUSB_BCM
>         bool "Broadcom protocol support"
>         depends on BT_HCIBTUSB
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index b14102fba601..38cb5448fc69 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -30,7 +30,7 @@
>  static bool disable_scofix;
>  static bool force_scofix;
>  static bool enable_autosuspend = IS_ENABLED(CONFIG_BT_HCIBTUSB_AUTOSUSPEND);
> -
> +static bool enable_interval = IS_ENABLED(CONFIG_BT_HCIBTUSB_INTERVAL);
>  static bool reset = true;
>
>  static struct usb_driver btusb_driver;
> @@ -519,8 +519,12 @@ struct btusb_data {
>
>         unsigned long flags;
>
> -       struct work_struct work;
> -       struct work_struct waker;
> +       struct work_struct  work;
> +       struct work_struct  waker;
> +       struct delayed_work rx_work;
> +
> +       struct sk_buff_head acl_q;
> +       struct sk_buff_head evt_q;
>
>         struct usb_anchor deferred;
>         struct usb_anchor tx_anchor;
> @@ -557,7 +561,7 @@ struct btusb_data {
>         int isoc_altsetting;
>         int suspend_count;
>
> -       int (*recv_event)(struct hci_dev *hdev, struct sk_buff *skb);
> +       int (*recv_event)(struct btusb_data *data, struct sk_buff *skb);
>         int (*recv_bulk)(struct btusb_data *data, void *buffer, int count);
>
>         int (*setup_on_usb)(struct hci_dev *hdev);
> @@ -707,7 +711,7 @@ static int btusb_recv_intr(struct btusb_data *data, void *buffer, int count)
>
>                 if (!hci_skb_expect(skb)) {
>                         /* Complete frame */
> -                       data->recv_event(data->hdev, skb);
> +                       data->recv_event(data, skb);
>                         skb = NULL;
>                 }
>         }
> @@ -718,6 +722,25 @@ static int btusb_recv_intr(struct btusb_data *data, void *buffer, int count)
>         return err;
>  }
>
> +static int btusb_rx_queue(struct btusb_data *data, struct sk_buff *skb,
> +                         struct sk_buff_head *queue, unsigned int interval)
> +{
> +       skb_queue_tail(queue, skb);
> +
> +       schedule_delayed_work(&data->rx_work, interval);
> +
> +       return 0;
> +}
> +
> +static int btusb_recv_acl(struct btusb_data *data, struct sk_buff *skb)
> +{
> +       if (!enable_interval)
> +               return hci_recv_frame(data->hdev, skb);
> +
> +       /* TODO: Calculate polling interval based on endpoint bInterval? */
> +       return btusb_rx_queue(data, skb, &data->acl_q, msecs_to_jiffies(1));
> +}
> +
>  static int btusb_recv_bulk(struct btusb_data *data, void *buffer, int count)
>  {
>         struct sk_buff *skb;
> @@ -765,7 +788,7 @@ static int btusb_recv_bulk(struct btusb_data *data, void *buffer, int count)
>
>                 if (!hci_skb_expect(skb)) {
>                         /* Complete frame */
> -                       hci_recv_frame(data->hdev, skb);
> +                       btusb_recv_acl(data, skb);
>                         skb = NULL;
>                 }
>         }
> @@ -1383,9 +1406,13 @@ static int btusb_close(struct hci_dev *hdev)
>
>         BT_DBG("%s", hdev->name);
>
> +       cancel_delayed_work(&data->rx_work);
>         cancel_work_sync(&data->work);
>         cancel_work_sync(&data->waker);
>
> +       skb_queue_purge(&data->acl_q);
> +       skb_queue_purge(&data->evt_q);
> +
>         clear_bit(BTUSB_ISOC_RUNNING, &data->flags);
>         clear_bit(BTUSB_BULK_RUNNING, &data->flags);
>         clear_bit(BTUSB_INTR_RUNNING, &data->flags);
> @@ -1417,6 +1444,11 @@ static int btusb_flush(struct hci_dev *hdev)
>
>         BT_DBG("%s", hdev->name);
>
> +       cancel_delayed_work(&data->rx_work);
> +
> +       skb_queue_purge(&data->acl_q);
> +       skb_queue_purge(&data->evt_q);
> +
>         usb_kill_anchored_urbs(&data->tx_anchor);
>         btusb_free_frags(data);
>
> @@ -1769,6 +1801,25 @@ static void btusb_waker(struct work_struct *work)
>         usb_autopm_put_interface(data->intf);
>  }
>
> +static void btusb_rx_dequeue(struct btusb_data *data,
> +                            struct sk_buff_head *queue)
> +{
> +       struct sk_buff *skb;
> +
> +       while ((skb = skb_dequeue(queue)))
> +               hci_recv_frame(data->hdev, skb);
> +}
> +
> +static void btusb_rx_work(struct work_struct *work)
> +{
> +       struct btusb_data *data = container_of(work, struct btusb_data,
> +                                              rx_work.work);
> +
> +       /* Process HCI event packets so states changes are synchronized first */
> +       btusb_rx_dequeue(data, &data->evt_q);
> +       btusb_rx_dequeue(data, &data->acl_q);
> +}
> +
>  static int btusb_setup_bcm92035(struct hci_dev *hdev)
>  {
>         struct sk_buff *skb;
> @@ -2304,10 +2355,8 @@ static void btusb_intel_secure_send_result(struct btusb_data *data,
>                 wake_up_bit(&data->flags, BTUSB_DOWNLOADING);
>  }
>
> -static int btusb_recv_event_intel(struct hci_dev *hdev, struct sk_buff *skb)
> +static int btusb_recv_event_intel(struct btusb_data *data, struct sk_buff *skb)
>  {
> -       struct btusb_data *data = hci_get_drvdata(hdev);
> -
>         if (test_bit(BTUSB_BOOTLOADER, &data->flags)) {
>                 struct hci_event_hdr *hdr = (void *)skb->data;
>
> @@ -2336,7 +2385,7 @@ static int btusb_recv_event_intel(struct hci_dev *hdev, struct sk_buff *skb)
>                 }
>         }
>
> -       return hci_recv_frame(hdev, skb);
> +       return hci_recv_frame(data->hdev, skb);
>  }
>
>  static int btusb_send_frame_intel(struct hci_dev *hdev, struct sk_buff *skb)
> @@ -4279,6 +4328,15 @@ static int btusb_shutdown_qca(struct hci_dev *hdev)
>         return 0;
>  }
>
> +static int btusb_recv_evt(struct btusb_data *data, struct sk_buff *skb)
> +{
> +       if (!enable_interval)
> +               return hci_recv_frame(data->hdev, skb);
> +
> +       /* Don't delay event processing */
> +       return btusb_rx_queue(data, skb, &data->evt_q, 0);
> +}
> +
>  static int btusb_probe(struct usb_interface *intf,
>                        const struct usb_device_id *id)
>  {
> @@ -4362,6 +4420,11 @@ static int btusb_probe(struct usb_interface *intf,
>
>         INIT_WORK(&data->work, btusb_work);
>         INIT_WORK(&data->waker, btusb_waker);
> +       INIT_DELAYED_WORK(&data->rx_work, btusb_rx_work);
> +
> +       skb_queue_head_init(&data->acl_q);
> +       skb_queue_head_init(&data->evt_q);
> +
>         init_usb_anchor(&data->deferred);
>         init_usb_anchor(&data->tx_anchor);
>         spin_lock_init(&data->txlock);
> @@ -4378,7 +4441,7 @@ static int btusb_probe(struct usb_interface *intf,
>                 data->recv_bulk = btusb_recv_bulk_intel;
>                 set_bit(BTUSB_BOOTLOADER, &data->flags);
>         } else {
> -               data->recv_event = hci_recv_frame;
> +               data->recv_event = btusb_recv_evt;
>                 data->recv_bulk = btusb_recv_bulk;
>         }
>
> @@ -4867,6 +4930,9 @@ MODULE_PARM_DESC(force_scofix, "Force fixup of wrong SCO buffers size");
>  module_param(enable_autosuspend, bool, 0644);
>  MODULE_PARM_DESC(enable_autosuspend, "Enable USB autosuspend by default");
>
> +module_param(enable_interval, bool, 0644);
> +MODULE_PARM_DESC(enable_interval, "Enable USB polling interval by default");
> +
>  module_param(reset, bool, 0644);
>  MODULE_PARM_DESC(reset, "Send HCI reset command on initialization");
>
> --
> 2.26.2
>

Thanks,
Archie