Messages in this thread | | | Date | Thu, 17 Jan 2019 15:57:48 +0530 | From | Balakrishna Godavarthi <> | Subject | Re: [PATCH v8 3/3] Bluetooth: hci_qca: Disable IBS state machine and flush Tx buffer |
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On 2019-01-17 04:38, Matthias Kaehlcke wrote: > On Wed, Jan 16, 2019 at 05:16:03PM +0530, Balakrishna Godavarthi wrote: >> During hci down we observed IBS sleep commands are queued in the Tx >> buffer and hci_uart_write_work is sending data to the chip which is >> not required as the chip is powered off. This patch will disable IBS >> and flush the Tx buffer before we turn off the chip. >> >> Signed-off-by: Balakrishna Godavarthi <bgodavar@codeaurora.org> >> --- >> drivers/bluetooth/hci_qca.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c >> index 7e4afcf40da2..7330ba71ada4 100644 >> --- a/drivers/bluetooth/hci_qca.c >> +++ b/drivers/bluetooth/hci_qca.c >> @@ -1275,6 +1275,14 @@ 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. But serial port is >> + * still open, stop queueing the IBS data and flush all the buffered >> + * data in skb's. >> + */ >> + clear_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags); >> + qca_flush(hu); >> host_set_baudrate(hu, 2400); >> qca_send_power_pulse(hu, QCA_WCN3990_POWEROFF_PULSE); >> qca_power_setup(hu, false); > > Due to a race-condition there could be an IBS sleep command queued > even after clearing the bit and flushing the queue. > > In qca_enqueue() we have this: > > static int qca_enqueue(struct hci_uart *hu, struct sk_buff *skb) > { > ... > > /* Don't go to sleep in middle of patch download or > * Out-Of-Band(GPIOs control) sleep is selected. > */ > if (!test_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags)) { > skb_queue_tail(&qca->txq, skb); > return 0; > } > > spin_lock_irqsave(&qca->hci_ibs_lock, flags); > } > > With process X executing qca_power_shutdown() and process Y running > qca_enqueue() this could happen: > > [X] test_bit(STATE_IN_BAND_SLEEP_ENABLED) => set > [Y] clear_bit(STATE_IN_BAND_SLEEP_ENABLED) > [Y] qca_flush(hu); > [X] skb_queue_tail(&qca->txq, skb); > > The following should fix this race: > > --- a/drivers/bluetooth/hci_qca.c > +++ b/drivers/bluetooth/hci_qca.c > @@ -770,16 +770,17 @@ static int qca_enqueue(struct hci_uart *hu, > struct sk_buff *skb) > /* Prepend skb with frame type */ > memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1); > > + spin_lock_irqsave(&qca->hci_ibs_lock, flags); > + > /* Don't go to sleep in middle of patch download or > * Out-Of-Band(GPIOs control) sleep is selected. > */ > if (!test_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags)) { > skb_queue_tail(&qca->txq, skb); > + spin_unlock_irqrestore(&qca->hci_ibs_lock, flags); > return 0; > } > > - spin_lock_irqsave(&qca->hci_ibs_lock, flags); > - > /* Act according to current state */ > switch (qca->tx_ibs_state) { > case HCI_IBS_TX_AWAKE: > @@ -1275,13 +1276,17 @@ static const struct qca_vreg_data qca_soc_data > = { > static void qca_power_shutdown(struct hci_uart *hu) > { > struct qca_data *qca = hu->priv; > + unsigned long flags; > > /* From this point we go into power off state. But serial port is > * still open, stop queueing the IBS data and flush all the buffered > * data in skb's. > */ > + spin_lock_irqsave(&qca->hci_ibs_lock, flags); > clear_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags); > qca_flush(hu); > + spin_unlock_irqrestore(&qca->hci_ibs_lock, flags); > + [Bala]: Thanks for catch this. yes you are rite, we will have an byte queued in the skb. will update with the lock.
> host_set_baudrate(hu, 2400); > qca_send_power_pulse(hu, QCA_WCN3990_POWEROFF_PULSE); > qca_power_setup(hu, false); > > Cheers > > Matthias
-- Regards Balakrishna.
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