[PATCH v2] Bluetooth: Add Broadcom channel priority commands
Luiz Augusto von Dentz
luiz.dentz at gmail.com
Tue Apr 14 07:00:02 PDT 2026
Hi Sasha,
On Tue, Apr 7, 2026 at 1:46 PM Sasha Finkelstein via B4 Relay
<devnull+fnkl.kernel.gmail.com at kernel.org> wrote:
>
> From: Sasha Finkelstein <fnkl.kernel at gmail.com>
>
> Certain Broadcom bluetooth chips (bcm4377/bcm4378/bcm438) need ACL
> streams carrying audio to be set as "high priority" using a vendor
> specific command to prevent 10-ish second-long dropouts whenever
> something does a device scan. This patch sends the command when the
> socket priority is set to TC_PRIO_INTERACTIVE, as BlueZ does for audio.
>
> Signed-off-by: Sasha Finkelstein <fnkl.kernel at gmail.com>
> ---
> Changes in v2:
> - new ioctl got nack-ed, so let's use sk_priority as the trigger
> - Link to v1: https://lore.kernel.org/r/20260407-brcm-prio-v1-1-f38b17376640@gmail.com
> ---
> MAINTAINERS | 2 ++
> drivers/bluetooth/hci_bcm4377.c | 2 ++
> include/net/bluetooth/bluetooth.h | 4 ++++
> include/net/bluetooth/hci_core.h | 11 +++++++++++
> net/bluetooth/Kconfig | 7 +++++++
> net/bluetooth/Makefile | 1 +
> net/bluetooth/brcm.c | 29 +++++++++++++++++++++++++++++
> net/bluetooth/brcm.h | 17 +++++++++++++++++
> net/bluetooth/hci_conn.c | 28 ++++++++++++++++++++++++++++
> net/bluetooth/l2cap_sock.c | 13 +++++++++++++
> 10 files changed, 114 insertions(+)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c3fe46d7c4bc..81be021367ec 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2562,6 +2562,8 @@ F: include/dt-bindings/pinctrl/apple.h
> F: include/linux/mfd/macsmc.h
> F: include/linux/soc/apple/*
> F: include/uapi/drm/asahi_drm.h
> +F: net/bluetooth/brcm.c
> +F: net/bluetooth/brcm.h
>
> ARM/ARTPEC MACHINE SUPPORT
> M: Jesper Nilsson <jesper.nilsson at axis.com>
> diff --git a/drivers/bluetooth/hci_bcm4377.c b/drivers/bluetooth/hci_bcm4377.c
> index 925d0a635945..5f79920c0306 100644
> --- a/drivers/bluetooth/hci_bcm4377.c
> +++ b/drivers/bluetooth/hci_bcm4377.c
> @@ -2397,6 +2397,8 @@ static int bcm4377_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> if (bcm4377->hw->broken_le_ext_adv_report_phy)
> hci_set_quirk(hdev, HCI_QUIRK_FIXUP_LE_EXT_ADV_REPORT_PHY);
>
> + hci_set_brcm_capable(hdev);
> +
> pci_set_drvdata(pdev, bcm4377);
> hci_set_drvdata(hdev, bcm4377);
> SET_HCIDEV_DEV(hdev, &pdev->dev);
> diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
> index 69eed69f7f26..07a250673950 100644
> --- a/include/net/bluetooth/bluetooth.h
> +++ b/include/net/bluetooth/bluetooth.h
> @@ -457,6 +457,7 @@ struct l2cap_ctrl {
> };
>
> struct hci_dev;
> +struct hci_conn;
>
> typedef void (*hci_req_complete_t)(struct hci_dev *hdev, u8 status, u16 opcode);
> typedef void (*hci_req_complete_skb_t)(struct hci_dev *hdev, u8 status,
> @@ -469,6 +470,9 @@ void hci_req_cmd_complete(struct hci_dev *hdev, u16 opcode, u8 status,
> int hci_ethtool_ts_info(unsigned int index, int sk_proto,
> struct kernel_ethtool_ts_info *ts_info);
>
> +int hci_conn_setsockopt(struct hci_conn *conn, struct sock *sk, int level,
> + int optname, sockptr_t optval, unsigned int optlen);
> +
> #define HCI_REQ_START BIT(0)
> #define HCI_REQ_SKB BIT(1)
>
> diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> index a7bffb908c1e..947e7c2b08dd 100644
> --- a/include/net/bluetooth/hci_core.h
> +++ b/include/net/bluetooth/hci_core.h
> @@ -642,6 +642,10 @@ struct hci_dev {
> bool aosp_quality_report;
> #endif
>
> +#if IS_ENABLED(CONFIG_BT_BRCMEXT)
> + bool brcm_capable;
> +#endif
> +
> int (*open)(struct hci_dev *hdev);
> int (*close)(struct hci_dev *hdev);
> int (*flush)(struct hci_dev *hdev);
> @@ -1791,6 +1795,13 @@ static inline void hci_set_aosp_capable(struct hci_dev *hdev)
> #endif
> }
>
> +static inline void hci_set_brcm_capable(struct hci_dev *hdev)
> +{
> +#if IS_ENABLED(CONFIG_BT_BRCMEXT)
> + hdev->brcm_capable = true;
> +#endif
> +}
> +
> static inline void hci_devcd_setup(struct hci_dev *hdev)
> {
> #ifdef CONFIG_DEV_COREDUMP
> diff --git a/net/bluetooth/Kconfig b/net/bluetooth/Kconfig
> index 6b2b65a66700..0f2a5fbcafc5 100644
> --- a/net/bluetooth/Kconfig
> +++ b/net/bluetooth/Kconfig
> @@ -110,6 +110,13 @@ config BT_AOSPEXT
> This options enables support for the Android Open Source
> Project defined HCI vendor extensions.
>
> +config BT_BRCMEXT
> + bool "Enable Broadcom extensions"
> + depends on BT
> + help
> + This option enables support for the Broadcom defined HCI
> + vendor extensions.
> +
> config BT_DEBUGFS
> bool "Export Bluetooth internals in debugfs"
> depends on BT && DEBUG_FS
> diff --git a/net/bluetooth/Makefile b/net/bluetooth/Makefile
> index a7eede7616d8..b4c9013a46ce 100644
> --- a/net/bluetooth/Makefile
> +++ b/net/bluetooth/Makefile
> @@ -24,5 +24,6 @@ bluetooth-$(CONFIG_BT_LE) += iso.o
> bluetooth-$(CONFIG_BT_LEDS) += leds.o
> bluetooth-$(CONFIG_BT_MSFTEXT) += msft.o
> bluetooth-$(CONFIG_BT_AOSPEXT) += aosp.o
> +bluetooth-$(CONFIG_BT_BRCMEXT) += brcm.o
> bluetooth-$(CONFIG_BT_DEBUGFS) += hci_debugfs.o
> bluetooth-$(CONFIG_BT_SELFTEST) += selftest.o
> diff --git a/net/bluetooth/brcm.c b/net/bluetooth/brcm.c
> new file mode 100644
> index 000000000000..9aa0a265ab3d
> --- /dev/null
> +++ b/net/bluetooth/brcm.c
> @@ -0,0 +1,29 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2026 The Asahi Linux Contributors
> + */
> +
> +#include <net/bluetooth/bluetooth.h>
> +#include <net/bluetooth/hci_core.h>
> +
> +#include "brcm.h"
> +
> +int brcm_set_high_priority(struct hci_dev *hdev, u16 handle, bool enable)
> +{
> + struct sk_buff *skb;
> + u8 cmd[3];
> +
> + if (!hdev->brcm_capable)
> + return 0;
> +
> + cmd[0] = handle;
> + cmd[1] = handle >> 8;
Adding a packed struct and then using something like cpu_to_le16 is
probably preferable over above.
> + cmd[2] = !!enable;
> +
> + skb = hci_cmd_sync(hdev, 0xfc57, sizeof(cmd), cmd, HCI_CMD_TIMEOUT);
> + if (IS_ERR(skb))
> + return PTR_ERR(skb);
> +
> + kfree_skb(skb);
> + return 0;
> +}
> diff --git a/net/bluetooth/brcm.h b/net/bluetooth/brcm.h
> new file mode 100644
> index 000000000000..fdaee63bd1d2
> --- /dev/null
> +++ b/net/bluetooth/brcm.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2026 The Asahi Linux Contributors
> + */
> +
> +#if IS_ENABLED(CONFIG_BT_BRCMEXT)
> +
> +int brcm_set_high_priority(struct hci_dev *hdev, u16 handle, bool enable);
> +
> +#else
> +
> +static inline int brcm_set_high_priority(struct hci_dev *hdev, u16 handle, bool enable)
> +{
> + return 0;
> +}
> +
> +#endif
> diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> index 11d3ad8d2551..096163840f62 100644
> --- a/net/bluetooth/hci_conn.c
> +++ b/net/bluetooth/hci_conn.c
> @@ -35,6 +35,7 @@
> #include <net/bluetooth/iso.h>
> #include <net/bluetooth/mgmt.h>
>
> +#include "brcm.h"
> #include "smp.h"
> #include "eir.h"
>
> @@ -3070,6 +3071,33 @@ int hci_conn_set_phy(struct hci_conn *conn, u32 phys)
> }
> }
>
> +int hci_conn_setsockopt(struct hci_conn *conn, struct sock *sk, int level,
> + int optname, sockptr_t optval, unsigned int optlen)
> +{
> + int val;
> + bool old_high, new_high, changed;
> +
> + if (level != SOL_SOCKET)
> + return 0;
> +
> + if (optname != SO_PRIORITY)
> + return 0;
> +
> + if (optlen < sizeof(int))
> + return -EINVAL;
> +
> + if (copy_from_sockptr(&val, optval, sizeof(val)))
> + return -EFAULT;
> +
> + old_high = sk->sk_priority >= TC_PRIO_INTERACTIVE;
> + new_high = val >= TC_PRIO_INTERACTIVE;
> + changed = old_high != new_high;
> + if (!changed)
> + return 0;
> +
> + return brcm_set_high_priority(conn->hdev, conn->handle, new_high);
The skb carries the priority (skb->priority), not sure why you need to
capture the sk_priority instead, doing so ignores the load balance
that hci_core performs to avoid starving connections.
> +}
> +
> static int abort_conn_sync(struct hci_dev *hdev, void *data)
> {
> struct hci_conn *conn = data;
> diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
> index 71e8c1b45bce..d5eef87accc4 100644
> --- a/net/bluetooth/l2cap_sock.c
> +++ b/net/bluetooth/l2cap_sock.c
> @@ -891,6 +891,16 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname,
>
> BT_DBG("sk %p", sk);
>
> + if (level == SOL_SOCKET) {
> + conn = chan->conn;
> + if (conn)
> + err = hci_conn_setsockopt(conn->hcon, sock->sk, level,
> + optname, optval, optlen);
> + if (err)
> + return err;
> + return sock_setsockopt(sock, level, optname, optval, optlen);
> + }
> +
> if (level == SOL_L2CAP)
> return l2cap_sock_setsockopt_old(sock, optname, optval, optlen);
>
> @@ -1931,6 +1941,9 @@ static struct sock *l2cap_sock_alloc(struct net *net, struct socket *sock,
>
> INIT_LIST_HEAD(&l2cap_pi(sk)->rx_busy);
>
> + if (sock)
> + set_bit(SOCK_CUSTOM_SOCKOPT, &sock->flags);
This is more complicated than it needs to be. I'd just add a new
callback, `hdev->set_priority(handle, skb->priority)`, so the driver
is called whenever it needs to elevate a connection's priority, that
said there could be cases where a connection needs its priority set
momentarily to transmit A2DP, followed by OBEX packets that are best
effort. Therefore, `hci_conn` will probably need to track the priority
so it can detect when it needs changing on a per skb basis.
> chan = l2cap_chan_create();
> if (!chan) {
> sk_free(sk);
>
> ---
> base-commit: bfe62a454542cfad3379f6ef5680b125f41e20f4
> change-id: 20260407-brcm-prio-b630e6cc3834
>
> Best regards,
> --
> Sasha Finkelstein <fnkl.kernel at gmail.com>
>
>
--
Luiz Augusto von Dentz
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