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Subject: Re: [PATCH v3] Bluetooth: btusb: hci_event: handle msbc audio over
 USB Endpoints
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20191113033857.3508-1-sathish.narasimman@intel.com>
Date:   Fri, 22 Nov 2019 13:45:34 +0100
Cc:     linux-bluetooth <linux-bluetooth@vger.kernel.org>,
        Sathish Narasimman <sathish.narasimman@intel.com>,
        Chethan T N <chethan.tumkur.narayan@intel.com>,
        Hsin-Yu Chao <hychao@chromium.org>,
        Amit K Bag <amit.k.bag@intel.com>
Content-Transfer-Encoding: 8BIT
Message-Id: <74403892-771B-4690-90DC-A88AB5107A60@holtmann.org>
References: <20191113033857.3508-1-sathish.narasimman@intel.com>
To:     Sathish Narsimman <nsathish41@gmail.com>
Sender: linux-bluetooth-owner@vger.kernel.org
Precedence: bulk

Hi Sathish,

> For msbc encoded audio stream over usb transport, btusb driver
> to be set to alternate settings 6 as per BT core spec 5.0. This
> done from  hci_sync_conn_complete_evt.  The type of air mode is known
> during this event.  For this reason the btusb is to be notifed
> about the TRANSPARENT air mode and the ALT setting 6 is selected.
> The changes are made considering some discussion over the similar
> patch submitted earlier from Kuba Pawlak(link below)
> https://www.spinics.net/lists/linux-bluetooth/msg64577.html
> 
> (am from https://www.spinics.net/lists/linux-bluetooth/msg76982.html)
> 
> Reported-by: kbuild test robot <lkp@intel.com>
> Signed-off-by: Sathish Narasimman <sathish.narasimman@intel.com>
> Signed-off-by: Chethan T N <chethan.tumkur.narayan@intel.com>
> Signed-off-by: Hsin-Yu Chao <hychao@chromium.org>
> Signed-off-by: Amit K Bag <amit.k.bag@intel.com>
> ---
> drivers/bluetooth/btusb.c        | 157 ++++++++++++++++++++++++-------
> include/net/bluetooth/hci.h      |   7 +-
> include/net/bluetooth/hci_core.h |   3 +
> net/bluetooth/hci_conn.c         |   2 -
> net/bluetooth/hci_event.c        |   9 ++
> 5 files changed, 137 insertions(+), 41 deletions(-)
> 
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index 04a139e7793f..7a4260757822 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -483,6 +483,8 @@ struct btusb_data {
> 	__u8 cmdreq;
> 
> 	unsigned int sco_num;
> +	unsigned int air_mode;
> +	bool usb_alt6_packet_flow;
> 	int isoc_altsetting;
> 	int suspend_count;
> 
> @@ -974,6 +976,42 @@ static void btusb_isoc_complete(struct urb *urb)
> 	}
> }
> 
> +static inline void __fill_isoc_descriptor_msbc(struct urb *urb, int len,
> +					       int mtu, bool packet_flow)
> +{
> +	int i, offset = 0;
> +	unsigned int interval;
> +
> +	/* For msbc ALT 6 setting the host will send the packet at continuous
> +	 * flow. As per core spec 5, vol 4, part B, table 2.1. For ALT setting
> +	 * 6 the HCI PACKET INTERVAL should be 7.5ms for every usb packets.
> +	 * To maintain the rate we send 63bytes of usb packets alternatively for
> +	 * 7ms and 8ms to maintain the rate as 7.5ms.
> +	 */
> +	if (packet_flow) {
> +		interval = 7;
> +		packet_flow = false;
> +	} else {
> +		interval = 6;
> +		packet_flow = true;
> +	}
> +
> +	BT_DBG("interval:%d len %d mtu %d", interval, len, mtu);
> +
> +	for (i = 0; i < interval; i++) {
> +		urb->iso_frame_desc[i].offset = offset;
> +		urb->iso_frame_desc[i].length = offset;
> +	}
> +
> +	if (len && i < BTUSB_MAX_ISOC_FRAMES) {
> +		urb->iso_frame_desc[i].offset = offset;
> +		urb->iso_frame_desc[i].length = len;
> +		i++;
> +	}
> +
> +	urb->number_of_packets = i;
> +}
> +
> static inline void __fill_isoc_descriptor(struct urb *urb, int len, int mtu)
> {
> 	int i, offset = 0;
> @@ -1376,9 +1414,13 @@ static struct urb *alloc_isoc_urb(struct hci_dev *hdev, struct sk_buff *skb)
> 
> 	urb->transfer_flags  = URB_ISO_ASAP;
> 
> -	__fill_isoc_descriptor(urb, skb->len,
> +	if (data->isoc_altsetting == 6)
> +		__fill_isoc_descriptor_msbc(urb, skb->len,
> +			       le16_to_cpu(data->isoc_tx_ep->wMaxPacketSize),
> +			       data->usb_alt6_packet_flow);
> +	else
> +		__fill_isoc_descriptor(urb, skb->len,
> 			       le16_to_cpu(data->isoc_tx_ep->wMaxPacketSize));
> -
> 	skb->dev = (void *)hdev;
> 
> 	return urb;
> @@ -1474,6 +1516,7 @@ static void btusb_notify(struct hci_dev *hdev, unsigned int evt)
> 
> 	if (hci_conn_num(hdev, SCO_LINK) != data->sco_num) {
> 		data->sco_num = hci_conn_num(hdev, SCO_LINK);
> +		data->air_mode = evt;
> 		schedule_work(&data->work);
> 	}
> }
> @@ -1521,11 +1564,70 @@ static inline int __set_isoc_interface(struct hci_dev *hdev, int altsetting)
> 	return 0;
> }
> 
> +static int bt_switch_alt_setting(struct hci_dev *hdev, int new_alts)
> +{
> +	struct btusb_data *data = hci_get_drvdata(hdev);
> +	int err;
> +
> +	if (data->isoc_altsetting != new_alts) {
> +		unsigned long flags;
> +
> +		clear_bit(BTUSB_ISOC_RUNNING, &data->flags);
> +		usb_kill_anchored_urbs(&data->isoc_anchor);
> +
> +		/* When isochronous alternate setting needs to be
> +		 * changed, because SCO connection has been added
> +		 * or removed, a packet fragment may be left in the
> +		 * reassembling state. This could lead to wrongly
> +		 * assembled fragments.
> +		 *
> +		 * Clear outstanding fragment when selecting a new
> +		 * alternate setting.
> +		 */
> +		spin_lock_irqsave(&data->rxlock, flags);
> +		kfree_skb(data->sco_skb);
> +		data->sco_skb = NULL;
> +		spin_unlock_irqrestore(&data->rxlock, flags);
> +
> +		err = __set_isoc_interface(hdev, new_alts);
> +		if (err < 0)
> +			return err;
> +	}
> +	if (!test_and_set_bit(BTUSB_ISOC_RUNNING, &data->flags)) {
> +		if (btusb_submit_isoc_urb(hdev, GFP_KERNEL) < 0)
> +			clear_bit(BTUSB_ISOC_RUNNING, &data->flags);
> +		else
> +			btusb_submit_isoc_urb(hdev, GFP_KERNEL);
> +	}
> +
> +	return 0;
> +}
> +
> +static struct usb_host_interface *btusb_find_altsetting(struct btusb_data *data, int alt)
> +{
> +	struct usb_interface *intf = data->isoc;
> +	int i;
> +
> +	BT_DBG("Looking for Alt no :%d", alt);
> +
> +	if (intf == NULL) {
> +		BT_ERR("INterface NULL");
> +		return NULL;
> +	}
> +
> +	for (i = 0; i < intf->num_altsetting; i++) {
> +		if (intf->altsetting[i].desc.bAlternateSetting == alt)
> +			return &intf->altsetting[i];
> +	}
> +
> +	return NULL;
> +}
> +
> static void btusb_work(struct work_struct *work)
> {
> 	struct btusb_data *data = container_of(work, struct btusb_data, work);
> 	struct hci_dev *hdev = data->hdev;
> -	int new_alts;
> +	int new_alts = 0;
> 	int err;
> 
> 	if (data->sco_num > 0) {
> @@ -1540,44 +1642,27 @@ static void btusb_work(struct work_struct *work)
> 			set_bit(BTUSB_DID_ISO_RESUME, &data->flags);
> 		}
> 
> -		if (hdev->voice_setting & 0x0020) {
> -			static const int alts[3] = { 2, 4, 5 };
> -
> -			new_alts = alts[data->sco_num - 1];
> -		} else {
> -			new_alts = data->sco_num;
> -		}
> -
> -		if (data->isoc_altsetting != new_alts) {
> -			unsigned long flags;
> +		if (data->air_mode == HCI_NOTIFY_ENABLE_SCO_CVSD) {
> +			if (hdev->voice_setting & 0x0020) {
> +				static const int alts[3] = { 2, 4, 5 };
> 
> -			clear_bit(BTUSB_ISOC_RUNNING, &data->flags);
> -			usb_kill_anchored_urbs(&data->isoc_anchor);
> -
> -			/* When isochronous alternate setting needs to be
> -			 * changed, because SCO connection has been added
> -			 * or removed, a packet fragment may be left in the
> -			 * reassembling state. This could lead to wrongly
> -			 * assembled fragments.
> -			 *
> -			 * Clear outstanding fragment when selecting a new
> -			 * alternate setting.
> -			 */
> -			spin_lock_irqsave(&data->rxlock, flags);
> -			kfree_skb(data->sco_skb);
> -			data->sco_skb = NULL;
> -			spin_unlock_irqrestore(&data->rxlock, flags);
> +				new_alts = alts[data->sco_num - 1];
> +			} else {
> +				new_alts = data->sco_num;
> +			}
> +		} else if (data->air_mode == HCI_NOTIFY_ENABLE_SCO_TRANSP) {
> 
> -			if (__set_isoc_interface(hdev, new_alts) < 0)
> -				return;
> -		}
> +			data->usb_alt6_packet_flow = true;
> 
> -		if (!test_and_set_bit(BTUSB_ISOC_RUNNING, &data->flags)) {
> -			if (btusb_submit_isoc_urb(hdev, GFP_KERNEL) < 0)
> -				clear_bit(BTUSB_ISOC_RUNNING, &data->flags);
> +			/* Check if Alt 6 is supported for Transparent audio*/
> +			if (btusb_find_altsetting(data, 6))
> +				new_alts = 6;
> 			else
> -				btusb_submit_isoc_urb(hdev, GFP_KERNEL);
> +				BT_ERR("%s Device does not support ALT setting 6", hdev->name);
> 		}
> +
> +		if (bt_switch_alt_setting(hdev, new_alts) < 0)
> +			BT_ERR("%s Set USB Alt: %d failed!", hdev->name, new_alts);
> 	} else {
> 		clear_bit(BTUSB_ISOC_RUNNING, &data->flags);
> 		usb_kill_anchored_urbs(&data->isoc_anchor);
> diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> index 5bc1e30dedde..8183394c2cc0 100644
> --- a/include/net/bluetooth/hci.h
> +++ b/include/net/bluetooth/hci.h
> @@ -49,9 +49,10 @@
> #define HCI_DEV_SETUP			9
> 
> /* HCI notify events */
> -#define HCI_NOTIFY_CONN_ADD		1
> -#define HCI_NOTIFY_CONN_DEL		2
> -#define HCI_NOTIFY_VOICE_SETTING	3
> +#define HCI_NOTIFY_ENABLE_SCO_CVSD	1
> +#define HCI_NOTIFY_ENABLE_SCO_TRANSP	2
> +#define HCI_NOTIFY_CONN_DEL		3
> +#define HCI_NOTIFY_VOICE_SETTING	4

hmmm. Can we keep CONN_ADD and CONN_DEL for the ACL and LE links. And then introduce ENABLE_SCO_CVSD, ENABLE_SCO_TRANSP and DISABLE_SCO. Right now this patch creates an imbalance.

And we need to split the core changes and the USB driver changes into separate patches.

Regards

Marcel