linux-kernel - [PATCH v2 3/5] Bluetooth: hci_event: Add quirk to ignore byte in LE Extended Adv Report

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Message-Id: <20220907170935.11757-4-sven@svenpeter.dev>
Date:   Wed,  7 Sep 2022 19:09:33 +0200
From:   Sven Peter <sven@...npeter.dev>
To:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc:     Sven Peter <sven@...npeter.dev>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Rob Herring <robh+dt@...nel.org>,
        Hector Martin <marcan@...can.st>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        asahi@...ts.linux.dev, netdev@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/5] Bluetooth: hci_event: Add quirk to ignore byte in LE Extended Adv Report

Broadcom controllers present on Apple Silicon devices use the upper
8 bits of the event type in the LE Extended Advertising Report for
the channel on which the frame has been received.
Add a quirk to drop the upper byte to ensure that the advertising
results are parsed correctly.

The following excerpt from a btmon trace shows a report received on
channel 37 by these controllers:

> HCI Event: LE Meta Event (0x3e) plen 55
      LE Extended Advertising Report (0x0d)
        Num reports: 1
        Entry 0
          Event type: 0x2513
            Props: 0x0013
              Connectable
              Scannable
              Use legacy advertising PDUs
            Data status: Complete
            Reserved (0x2500)
          Legacy PDU Type: Reserved (0x2513)
          Address type: Public (0x00)
          Address: XX:XX:XX:XX:XX:XX (Shenzhen Jingxun Software [...])
          Primary PHY: LE 1M
          Secondary PHY: No packets
          SID: no ADI field (0xff)
          TX power: 127 dBm
          RSSI: -76 dBm (0xb4)
          Periodic advertising interval: 0.00 msec (0x0000)
          Direct address type: Public (0x00)
          Direct address: 00:00:00:00:00:00 (OUI 00-00-00)
          Data length: 0x1d
          [...]
        Flags: 0x18
          Simultaneous LE and BR/EDR (Controller)
          Simultaneous LE and BR/EDR (Host)
        Company: Harman International Industries, Inc. (87)
          Data: [...]
        Service Data (UUID 0xfddf):
        Name (complete): JBL Flip 5

Signed-off-by: Sven Peter <sven@...npeter.dev>
---
changes from v1:
  - adjusted the commit message a bit to make checkpatch happy

 include/net/bluetooth/hci.h | 11 +++++++++++
 net/bluetooth/hci_event.c   |  4 ++++
 2 files changed, 15 insertions(+)

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index cf29511b25a8..62539c1a6bf2 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -263,6 +263,17 @@ enum {
 	 * during the hdev->setup vendor callback.
 	 */
 	HCI_QUIRK_BROKEN_ENHANCED_SETUP_SYNC_CONN,
+
+	/*
+	 * When this quirk is set, the upper 8 bits of the evt_type field of
+	 * the LE Extended Advertising Report events are discarded.
+	 * Some Broadcom controllers found in Apple machines put the channel
+	 * the report was received on into these reserved bits.
+	 *
+	 * This quirk can be set before hci_register_dev is called or
+	 * during the hdev->setup vendor callback.
+	 */
+	HCI_QUIRK_FIXUP_LE_EXT_ADV_REPORT_EVT_TYPE,
 };
 
 /* HCI device flags */
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 485c814cf44a..b50d05211f0d 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -6471,6 +6471,10 @@ static void hci_le_ext_adv_report_evt(struct hci_dev *hdev, void *data,
 			break;
 
 		evt_type = __le16_to_cpu(info->type);
+		if (test_bit(HCI_QUIRK_FIXUP_LE_EXT_ADV_REPORT_EVT_TYPE,
+			     &hdev->quirks))
+			evt_type &= 0xff;
+
 		legacy_evt_type = ext_evt_type_to_legacy(hdev, evt_type);
 		if (legacy_evt_type != LE_ADV_INVALID) {
 			process_adv_report(hdev, legacy_evt_type, &info->bdaddr,
-- 
2.25.1