Re: [PATCH v2 3/3] Bluetooth: hci_qca: Fix frame reassembly errors for wcn3990

Matthias Kaehlcke
2018-11-27T00:09:54Z

On Thu, Nov 22, 2018 at 05:45:12PM +0530, Balakrishna Godavarthi wrote:
> During initalization of wcn3990, we observed UART is reading some
> stray bytes on the Rx line. This is logging Frame reassembly errors
> on the serial console. This could be because of tristate of Tx line
> of wcn3990 during boot up.
>
> [ 176.929612] Bluetooth: hci_qca.c:qca_recv() hci0: Frame reassembly failed (-84)
> [ 176.945734] Bluetooth: hci_qca.c:qca_recv() hci0: Frame reassembly failed (-84)
> [ 176.953298] Bluetooth: hci_qca.c:qca_recv() hci0: Frame reassembly failed (-84)
> [ 177.010660] Bluetooth: hci_qca.c:qca_recv() hci0: Frame reassembly failed (-84)
> [ 177.067633] Bluetooth: hci_qca.c:qca_recv() hci0: Frame reassembly failed (-84)
>
> Now we enable a flag during bootup to stop executing proto receive
> function and clear it back once the initialization is done.
>
> Signed-off-by: Balakrishna Godavarthi <bgodavar@codeaurora.org>
> Tested-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> v2:
> * Updated commit text & comments.
> v1:
> * initial patch
> ---
> drivers/bluetooth/hci_qca.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index ed905ea1c58a..2f3d9e16ba5a 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -56,6 +56,7 @@
>
> /* Controller states */
> #define STATE_IN_BAND_SLEEP_ENABLED 1
> +#define STATE_DISCARD_RX 2
>
> #define IBS_WAKE_RETRANS_TIMEOUT_MS 100
> #define IBS_TX_IDLE_TIMEOUT_MS 2000
> @@ -511,6 +512,7 @@ static int qca_open(struct hci_uart *hu)
> } else {
> hu->init_speed = qcadev->init_speed;
> hu->oper_speed = qcadev->oper_speed;
> + set_bit(STATE_DISCARD_RX, &qca->flags);
> ret = qca_power_setup(hu, true);
> if (ret) {
> destroy_workqueue(qca->workqueue);
> @@ -903,6 +905,13 @@ static int qca_recv(struct hci_uart *hu, const void *data, int count)
> if (!test_bit(HCI_UART_REGISTERED, &hu->flags))
> return -EUNATCH;
>
> + /* We discard Rx data received while device is in booting
> + * stage, This is because of BT chip Tx line is in tristate.
> + * Due to this we read some garbage data on UART Rx.
> + */
> + if (test_bit(STATE_DISCARD_RX, &qca->flags))
> + return 0;
> +
> qca->rx_skb = h4_recv_buf(hu->hdev, qca->rx_skb, data, count,
> qca_recv_pkts, ARRAY_SIZE(qca_recv_pkts));
> if (IS_ERR(qca->rx_skb)) {
> @@ -1193,6 +1202,7 @@ static int qca_setup(struct hci_uart *hu)
> if (ret)
> return ret;
>
> + clear_bit(STATE_DISCARD_RX, &qca->flags);
> ret = qca_read_soc_version(hdev, &soc_ver);
> if (ret)
> return ret;
> @@ -1269,6 +1279,14 @@ static const struct qca_vreg_data qca_soc_data = {
>
> static void qca_power_shutdown(struct hci_uart *hu)
> {
> + struct qca_data *qca = hu->priv;
> +
> + /* From this point we go into power off state,
> + * disable IBS and discard all the queued data.
> + */
> + clear_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags);

Is IBS actually related to the frame reassembly errors or is this
addressing a different issue? In 100 iteratios of 'hciconfig up/down'
without clearing the flag I didn't observe any frame reassembly
errors.

> + set_bit(STATE_DISCARD_RX, &qca->flags);
> + qca_flush(hu);
> host_set_baudrate(hu, 2400);
> qca_send_power_pulse(hu, QCA_WCN3990_POWEROFF_PULSE);
> qca_power_setup(hu, false);