linux-kernel - [PATCH v2 4/5] Bluetooth: Add quirk to disable extended scanning

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Message-Id: <20220907170935.11757-5-sven@svenpeter.dev>
Date:   Wed,  7 Sep 2022 19:09:34 +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 4/5] Bluetooth: Add quirk to disable extended scanning

Broadcom 4377 controllers found in Apple x86 Macs with the T2 chip
claim to support extended scanning when querying supported states,

< HCI Command: LE Read Supported St.. (0x08|0x001c) plen 0
> HCI Event: Command Complete (0x0e) plen 12
      LE Read Supported States (0x08|0x001c) ncmd 1
        Status: Success (0x00)
        States: 0x000003ffffffffff
[...]
          LE Set Extended Scan Parameters (Octet 37 - Bit 5)
          LE Set Extended Scan Enable (Octet 37 - Bit 6)
[...]

, but then fail to actually implement the extended scanning:

< HCI Command: LE Set Extended Sca.. (0x08|0x0041) plen 8
        Own address type: Random (0x01)
        Filter policy: Accept all advertisement (0x00)
        PHYs: 0x01
        Entry 0: LE 1M
          Type: Active (0x01)
          Interval: 11.250 msec (0x0012)
          Window: 11.250 msec (0x0012)
> HCI Event: Command Complete (0x0e) plen 4
      LE Set Extended Scan Parameters (0x08|0x0041) ncmd 1
        Status: Unknown HCI Command (0x01)

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      | 10 ++++++++++
 include/net/bluetooth/hci_core.h |  4 +++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
index 62539c1a6bf2..05a13b0c5ff1 100644
--- a/include/net/bluetooth/hci.h
+++ b/include/net/bluetooth/hci.h
@@ -274,6 +274,16 @@ enum {
 	 * during the hdev->setup vendor callback.
 	 */
 	HCI_QUIRK_FIXUP_LE_EXT_ADV_REPORT_EVT_TYPE,
+
+	/*
+	 * When this quirk is set, the HCI_OP_LE_SET_EXT_SCAN_ENABLE command is
+	 * disabled. This is required for some Broadcom controllers which
+	 * erroneously claim to support extended scanning.
+	 *
+	 * This quirk can be set before hci_register_dev is called or
+	 * during the hdev->setup vendor callback.
+	 */
+	HCI_QUIRK_BROKEN_EXT_SCAN,
 };
 
 /* HCI device flags */
diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index e7862903187d..29d1254f9856 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -1681,7 +1681,9 @@ void hci_conn_del_sysfs(struct hci_conn *conn);
 
 /* Use ext scanning if set ext scan param and ext scan enable is supported */
 #define use_ext_scan(dev) (((dev)->commands[37] & 0x20) && \
-			   ((dev)->commands[37] & 0x40))
+			   ((dev)->commands[37] & 0x40) && \
+			   !test_bit(HCI_QUIRK_BROKEN_EXT_SCAN, &(dev)->quirks))
+
 /* Use ext create connection if command is supported */
 #define use_ext_conn(dev) ((dev)->commands[37] & 0x80)
 
-- 
2.25.1