From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Kaehlcke Subject: Re: [PATCH v9 3/3] Bluetooth: hci_qca: Disable IBS state machine and flush Tx buffer Date: Fri, 1 Feb 2019 10:35:06 -0800 Message-ID: <20190201183506.GR81583@google.com> References: <20190124120808.8275-1-bgodavar@codeaurora.org> <20190124120808.8275-4-bgodavar@codeaurora.org> <20190125005534.GC81583@google.com> <75923da910c43e7e5e033f4ff4360a90@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: <75923da910c43e7e5e033f4ff4360a90@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org To: Balakrishna Godavarthi Cc: marcel@holtmann.org, johan.hedberg@gmail.com, johan@kernel.org, linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org, hemantg@codeaurora.org, linux-arm-msm@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org On Fri, Feb 01, 2019 at 05:10:11PM +0530, Balakrishna Godavarthi wrote: > Hi Matthias, > > On 2019-01-25 06:25, Matthias Kaehlcke wrote: > > On Thu, Jan 24, 2019 at 05:38:08PM +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 > > > --- > > > Changes v9: > > > * added lock while disabling the IBS state machine. > > > > > > --- > > > drivers/bluetooth/hci_qca.c | 17 +++++++++++++++-- > > > 1 file changed, 15 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c > > > index 6b5bcd44e24c..99ddc35f08c6 100644 > > > --- a/drivers/bluetooth/hci_qca.c > > > +++ b/drivers/bluetooth/hci_qca.c > > > @@ -771,16 +771,17 @@ 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: > > > @@ -1273,6 +1274,18 @@ 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); > > > + > > > host_set_baudrate(hu, 2400); > > > qca_send_power_pulse(hu, QCA_WCN3990_POWEROFF_PULSE); > > > qca_power_setup(hu, false); > > > > I was about to add my 'Reviewed-by' tag, but I'm still left with a > > doubt. This patch certainly improves the situation by clearing the IBS > > bit and flushing the buffered data, however IIUC new data could still > > be added to the TX queue after releasing the spinlock: > > > > static int qca_enqueue(struct hci_uart *hu, struct sk_buff *skb) > > { > > ... > > > > if (!test_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags)) { > > skb_queue_tail(&qca->txq, skb); > > > > ... > > } > > > > To prevent this a boolean/bit like 'shutting_down' or similar would be > > needed (I don't think there is something common in the HCI core), > > which is set in qca_power_shutdown(). If the bit is set qca_enqueue() > > discards the data. > > > > Not sure how important this is, and I don't want to add necessarily > > more revisions to this series. If it is preferable to have an empty > > queue after shutdown maybe it can be done in a follow up patch. > > > > Thanks > > > > Matthias > > [Bala]: during shutdown Bt stack will not send any data to the Bt kernel Tx > path. > so this call may not be called. once we shutdown chip. Thanks for the clarification! I kinda expected that, but it wasn't evident to me from the core code. Reviewed-by: Matthias Kaehlcke