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Message-ID: <20200819143821.qptlcrshcamlk4x3@pali>
Date: Wed, 19 Aug 2020 16:38:21 +0200
From: Pali Rohár <pali@...nel.org>
To: Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc: Joseph Hwang <josephsih@...omium.org>,
"linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>,
Marcel Holtmann <marcel@...tmann.org>,
Joseph Hwang <josephsih@...gle.com>,
ChromeOS Bluetooth Upstreaming
<chromeos-bluetooth-upstreaming@...omium.org>,
Alain Michaud <alainm@...omium.org>,
Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Johan Hedberg <johan.hedberg@...il.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"open list:NETWORKING [GENERAL]" <netdev@...r.kernel.org>
Subject: Re: [PATCH v1 1/2] Bluetooth: btusb: define HCI packet sizes of USB
Alts
On Friday 14 August 2020 13:07:25 Luiz Augusto von Dentz wrote:
> Hi Joseph,
>
> On Thu, Aug 13, 2020 at 1:42 AM Joseph Hwang <josephsih@...omium.org> wrote:
> >
> > It is desirable to define the HCI packet payload sizes of
> > USB alternate settings so that they can be exposed to user
> > space.
> >
> > Reviewed-by: Alain Michaud <alainm@...omium.org>
> > Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> > Signed-off-by: Joseph Hwang <josephsih@...omium.org>
> > ---
> >
> > drivers/bluetooth/btusb.c | 43 ++++++++++++++++++++++++--------
> > include/net/bluetooth/hci_core.h | 1 +
> > 2 files changed, 33 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> > index 8d2608ddfd0875..df7cadf6385868 100644
> > --- a/drivers/bluetooth/btusb.c
> > +++ b/drivers/bluetooth/btusb.c
> > @@ -459,6 +459,22 @@ static const struct dmi_system_id btusb_needs_reset_resume_table[] = {
> > #define BTUSB_WAKEUP_DISABLE 14
> > #define BTUSB_USE_ALT1_FOR_WBS 15
> >
> > +/* Per core spec 5, vol 4, part B, table 2.1,
> > + * list the hci packet payload sizes for various ALT settings.
> > + * This is used to set the packet length for the wideband speech.
> > + * If a controller does not probe its usb alt setting, the default
> > + * value will be 0. Any clients at upper layers should interpret it
> > + * as a default value and set a proper packet length accordingly.
> > + *
> > + * To calculate the HCI packet payload length:
> > + * for alternate settings 1 - 5:
> > + * hci_packet_size = suggested_max_packet_size * 3 (packets) -
> > + * 3 (HCI header octets)
> > + * for alternate setting 6:
> > + * hci_packet_size = suggested_max_packet_size - 3 (HCI header octets)
> > + */
> > +static const int hci_packet_size_usb_alt[] = { 0, 24, 48, 72, 96, 144, 60 };
> > +
> > struct btusb_data {
> > struct hci_dev *hdev;
> > struct usb_device *udev;
> > @@ -3958,6 +3974,15 @@ static int btusb_probe(struct usb_interface *intf,
> > hdev->notify = btusb_notify;
> > hdev->prevent_wake = btusb_prevent_wake;
> >
> > + if (id->driver_info & BTUSB_AMP) {
> > + /* AMP controllers do not support SCO packets */
> > + data->isoc = NULL;
> > + } else {
> > + /* Interface orders are hardcoded in the specification */
> > + data->isoc = usb_ifnum_to_if(data->udev, ifnum_base + 1);
> > + data->isoc_ifnum = ifnum_base + 1;
> > + }
> > +
> > #ifdef CONFIG_PM
> > err = btusb_config_oob_wake(hdev);
> > if (err)
> > @@ -4021,6 +4046,10 @@ static int btusb_probe(struct usb_interface *intf,
> > hdev->set_diag = btintel_set_diag;
> > hdev->set_bdaddr = btintel_set_bdaddr;
> > hdev->cmd_timeout = btusb_intel_cmd_timeout;
> > +
> > + if (btusb_find_altsetting(data, 6))
> > + hdev->sco_pkt_len = hci_packet_size_usb_alt[6];
> > +
> > set_bit(HCI_QUIRK_STRICT_DUPLICATE_FILTER, &hdev->quirks);
> > set_bit(HCI_QUIRK_SIMULTANEOUS_DISCOVERY, &hdev->quirks);
> > set_bit(HCI_QUIRK_NON_PERSISTENT_DIAG, &hdev->quirks);
> > @@ -4062,15 +4091,6 @@ static int btusb_probe(struct usb_interface *intf,
> > btusb_check_needs_reset_resume(intf);
> > }
> >
> > - if (id->driver_info & BTUSB_AMP) {
> > - /* AMP controllers do not support SCO packets */
> > - data->isoc = NULL;
> > - } else {
> > - /* Interface orders are hardcoded in the specification */
> > - data->isoc = usb_ifnum_to_if(data->udev, ifnum_base + 1);
> > - data->isoc_ifnum = ifnum_base + 1;
> > - }
> > -
> > if (IS_ENABLED(CONFIG_BT_HCIBTUSB_RTL) &&
> > (id->driver_info & BTUSB_REALTEK)) {
> > hdev->setup = btrtl_setup_realtek;
> > @@ -4082,9 +4102,10 @@ static int btusb_probe(struct usb_interface *intf,
> > * (DEVICE_REMOTE_WAKEUP)
> > */
> > set_bit(BTUSB_WAKEUP_DISABLE, &data->flags);
> > - if (btusb_find_altsetting(data, 1))
> > + if (btusb_find_altsetting(data, 1)) {
> > set_bit(BTUSB_USE_ALT1_FOR_WBS, &data->flags);
> > - else
> > + hdev->sco_pkt_len = hci_packet_size_usb_alt[1];
> > + } else
> > bt_dev_err(hdev, "Device does not support ALT setting 1");
> > }
> >
> > diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> > index 8caac20556b499..0624496328fc09 100644
> > --- a/include/net/bluetooth/hci_core.h
> > +++ b/include/net/bluetooth/hci_core.h
> > @@ -417,6 +417,7 @@ struct hci_dev {
> > unsigned int acl_pkts;
> > unsigned int sco_pkts;
> > unsigned int le_pkts;
> > + unsigned int sco_pkt_len;
>
> Id use sco_mtu to so the following check actually does what it intended to do:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next.git/tree/net/bluetooth/sco.c#n283
>
> Right now it seems we are using the buffer length as MTU but I think
> we should actually use the packet length if it is lower than the
> buffer length, actually it doesn't seems SCO packets can be fragmented
> so the buffer length must always be big enough to carry a full packet
> so I assume setting the packet length as conn->mtu will always be
> correct.
I agree. We should use sco mtu for this purpose.
> >
> > __u16 block_len;
> > __u16 block_mtu;
> > --
> > 2.28.0.236.gb10cc79966-goog
> >
>
>
> --
> Luiz Augusto von Dentz
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