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Sun, 19 Apr 2026 00:24:47 -0700 (PDT) Received: from server ([5.14.142.56]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-488fc16f8c3sm169076205e9.2.2026.04.19.00.24.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Apr 2026 00:24:46 -0700 (PDT) From: StefanCondorache To: linux-bluetooth@vger.kernel.org Cc: marcel@holtmann.org, luiz.dentz@gmail.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, StefanCondorache Subject: [PATCH] Bluetooth: Add HCI_QUIRK_NO_SCAN_WHILE_CONNECTED for combo chips Date: Sun, 19 Apr 2026 10:24:33 +0300 Message-ID: <20260419072433.55976-1-condorachest@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Realtek combo chips share a single antenna between Wi-Fi and Bluetooth. Background LE passive scanning while an active connection exists causes antenna multiplexing conflicts via Packet Traffic Arbitration (PTA), resulting in audio stuttering and Wi-Fi packet loss. Add HCI_QUIRK_NO_SCAN_WHILE_CONNECTED to suppress passive scanning in hci_update_passive_scan_sync() when active connections are present. Set this quirk for all Realtek devices in btrtl_set_quirks(). Also add device ID 0x0bda:0xc829 to the btusb Realtek device table. Signed-off-by: StefanCondorache --- drivers/bluetooth/btrtl.c | 6 ++++++ drivers/bluetooth/btusb.c | 2 ++ include/net/bluetooth/hci.h | 11 +++++++++++ net/bluetooth/hci_sync.c | 7 +++++++ 4 files changed, 26 insertions(+) diff --git a/drivers/bluetooth/btrtl.c b/drivers/bluetooth/btrtl.c index 62f9d4df3a4f..00dfba656970 100644 --- a/drivers/bluetooth/btrtl.c +++ b/drivers/bluetooth/btrtl.c @@ -1299,6 +1299,12 @@ EXPORT_SYMBOL_GPL(btrtl_download_firmware); void btrtl_set_quirks(struct hci_dev *hdev, struct btrtl_device_info *btrtl_dev) { + /* Realtek combo chips share the antenna between Wi-Fi and + * Bluetooth. Suppress passive scanning while connected to + * prevent coexistence issues. + */ + hci_set_quirk(hdev, HCI_QUIRK_NO_SCAN_WHILE_CONNECTED); + /* Enable controller to do both LE scan and BR/EDR inquiry * simultaneously. */ diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c index 5f57953393be..87972f5fc567 100644 --- a/drivers/bluetooth/btusb.c +++ b/drivers/bluetooth/btusb.c @@ -516,6 +516,8 @@ static const struct usb_device_id quirks_table[] = { /* Realtek 8822CU Bluetooth devices */ { USB_DEVICE(0x13d3, 0x3549), .driver_info = BTUSB_REALTEK | BTUSB_WIDEBAND_SPEECH }, + { USB_DEVICE(0x0bda, 0xc829), .driver_info = BTUSB_REALTEK | + BTUSB_WIDEBAND_SPEECH }, /* Realtek 8851BE Bluetooth devices */ { USB_DEVICE(0x0bda, 0xb850), .driver_info = BTUSB_REALTEK }, diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h index 572b1c620c5d..8466dc52aeca 100644 --- a/include/net/bluetooth/hci.h +++ b/include/net/bluetooth/hci.h @@ -378,6 +378,17 @@ enum { */ HCI_QUIRK_BROKEN_READ_PAGE_SCAN_TYPE, + /* When this quirk is set, the controller suppresses passive LE + * background scanning while an active connection exists. + * This is required for combo chips with shared Wi-Fi/Bluetooth + * antennas to prevent coexistence issues causing audio drops + * and Wi-Fi packet loss. + * + * This quirk can be set before hci_register_dev is called or + * during the hdev->setup vendor callback. + */ + HCI_QUIRK_NO_SCAN_WHILE_CONNECTED, + __HCI_NUM_QUIRKS, }; diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c index fd3aacdea512..5e30e725efa2 100644 --- a/net/bluetooth/hci_sync.c +++ b/net/bluetooth/hci_sync.c @@ -3194,6 +3194,13 @@ int hci_update_passive_scan_sync(struct hci_dev *hdev) if (hdev->discovery.state != DISCOVERY_STOPPED) return 0; + /* If the controller requires no scanning while connected, + * suppress passive scanning when an active connection exists. + */ + if (hci_test_quirk(hdev, HCI_QUIRK_NO_SCAN_WHILE_CONNECTED) && + !list_empty(&hdev->conn_hash.list)) + return 0; + /* Reset RSSI and UUID filters when starting background scanning * since these filters are meant for service discovery only. * -- 2.53.0