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    SubjectRe: [PATCH v3] Bluetooth: Ignore CC events not matching the last HCI command
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    Hi Joao,

    > This commit makes the kernel not send the next queued HCI command until
    > a command complete arrives for the last HCI command sent to the
    > controller. This change avoids a problem with some buggy controllers
    > (seen on two SKUs of QCA9377) that send an extra command complete event
    > for the previous command after the kernel had already sent a new HCI
    > command to the controller.
    >
    > The problem was reproduced when starting an active scanning procedure,
    > where an extra command complete event arrives for the LE_SET_RANDOM_ADDR
    > command. When this happends the kernel ends up not processing the
    > command complete for the following commmand, LE_SET_SCAN_PARAM, and
    > ultimately behaving as if a passive scanning procedure was being
    > performed, when in fact controller is performing an active scanning
    > procedure. This makes it impossible to discover BLE devices as no device
    > found events are sent to userspace.
    >
    > This problem is reproducible on 100% of the attempts on the affected
    > controllers. The extra command complete event can be seen at timestamp
    > 27.420131 on the btmon logs bellow.
    >
    > Bluetooth monitor ver 5.50
    > = Note: Linux version 5.0.0+ (x86_64) 0.352340
    > = Note: Bluetooth subsystem version 2.22 0.352343
    > = New Index: 80:C5:F2:8F:87:84 (Primary,USB,hci0) [hci0] 0.352344
    > = Open Index: 80:C5:F2:8F:87:84 [hci0] 0.352345
    > = Index Info: 80:C5:F2:8F:87:84 (Qualcomm) [hci0] 0.352346
    > @ MGMT Open: bluetoothd (privileged) version 1.14 {0x0001} 0.352347
    > @ MGMT Open: btmon (privileged) version 1.14 {0x0002} 0.352366
    > @ MGMT Open: btmgmt (privileged) version 1.14 {0x0003} 27.302164
    > @ MGMT Command: Start Discovery (0x0023) plen 1 {0x0003} [hci0] 27.302310
    > Address type: 0x06
    > LE Public
    > LE Random
    > < HCI Command: LE Set Random Address (0x08|0x0005) plen 6 #1 [hci0] 27.302496
    > Address: 15:60:F2:91:B2:24 (Non-Resolvable)
    >> HCI Event: Command Complete (0x0e) plen 4 #2 [hci0] 27.419117
    > LE Set Random Address (0x08|0x0005) ncmd 1
    > Status: Success (0x00)
    > < HCI Command: LE Set Scan Parameters (0x08|0x000b) plen 7 #3 [hci0] 27.419244
    > Type: Active (0x01)
    > Interval: 11.250 msec (0x0012)
    > Window: 11.250 msec (0x0012)
    > Own address type: Random (0x01)
    > Filter policy: Accept all advertisement (0x00)
    >> HCI Event: Command Complete (0x0e) plen 4 #4 [hci0] 27.420131
    > LE Set Random Address (0x08|0x0005) ncmd 1
    > Status: Success (0x00)
    > < HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2 #5 [hci0] 27.420259
    > Scanning: Enabled (0x01)
    > Filter duplicates: Enabled (0x01)
    >> HCI Event: Command Complete (0x0e) plen 4 #6 [hci0] 27.420969
    > LE Set Scan Parameters (0x08|0x000b) ncmd 1
    > Status: Success (0x00)
    >> HCI Event: Command Complete (0x0e) plen 4 #7 [hci0] 27.421983
    > LE Set Scan Enable (0x08|0x000c) ncmd 1
    > Status: Success (0x00)
    > @ MGMT Event: Command Complete (0x0001) plen 4 {0x0003} [hci0] 27.422059
    > Start Discovery (0x0023) plen 1
    > Status: Success (0x00)
    > Address type: 0x06
    > LE Public
    > LE Random
    > @ MGMT Event: Discovering (0x0013) plen 2 {0x0003} [hci0] 27.422067
    > Address type: 0x06
    > LE Public
    > LE Random
    > Discovery: Enabled (0x01)
    > @ MGMT Event: Discovering (0x0013) plen 2 {0x0002} [hci0] 27.422067
    > Address type: 0x06
    > LE Public
    > LE Random
    > Discovery: Enabled (0x01)
    > @ MGMT Event: Discovering (0x0013) plen 2 {0x0001} [hci0] 27.422067
    > Address type: 0x06
    > LE Public
    > LE Random
    > Discovery: Enabled (0x01)
    >
    > Signed-off-by: João Paulo Rechi Vita <jprvita@endlessm.com>
    > ---
    > include/net/bluetooth/hci.h | 2 ++
    > net/bluetooth/hci_core.c | 5 +++++
    > net/bluetooth/hci_event.c | 12 ++++++++++++
    > net/bluetooth/hci_request.c | 4 ----
    > net/bluetooth/hci_request.h | 4 ++++
    > 5 files changed, 23 insertions(+), 4 deletions(-)
    >
    > diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
    > index fbba43e9bef5..883a8c25ccfb 100644
    > --- a/include/net/bluetooth/hci.h
    > +++ b/include/net/bluetooth/hci.h
    > @@ -221,6 +221,8 @@ enum {
    > HCI_RAW,
    >
    > HCI_RESET,
    > +
    > + HCI_CMD_PENDING,
    > };

    no new flags here please. This is userspace visible use the hdev->dev_flags.

    Regards

    Marcel

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