Messages in this thread | | | Date | Fri, 28 Dec 2018 12:41:24 +0530 | From | Balakrishna Godavarthi <> | Subject | Re: [PATCH v6 1/6] Bluetooth: hci_qca: use wait_until_sent() for power pulses |
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HI Matthias,
On 2018-12-28 01:48, Matthias Kaehlcke wrote: > On Thu, Dec 27, 2018 at 01:01:31PM +0530, Balakrishna Godavarthi wrote: >> wcn3990 requires a power pulse to turn ON/OFF along with >> regulators. Sometimes we are observing the power pulses are sent >> out with some time delay, due to queuing these commands. This is >> causing synchronization issues with chip, which intern delay the >> chip setup or may end up with communication issues. >> >> Signed-off-by: Balakrishna Godavarthi <bgodavar@codeaurora.org> >> --- >> Changes in v6: >> * added serdev_device_write_flush() in qca_send_power_pulse >> instead during the power off pulse. >> >> Changes in v5: >> * added serdev_device_write_flush() in qca_power_off(). >> >> --- >> drivers/bluetooth/hci_qca.c | 38 >> ++++++++++++++----------------------- >> 1 file changed, 14 insertions(+), 24 deletions(-) >> >> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c >> index f036c8f98ea3..507a2355c758 100644 >> --- a/drivers/bluetooth/hci_qca.c >> +++ b/drivers/bluetooth/hci_qca.c >> @@ -1013,11 +1013,9 @@ static inline void host_set_baudrate(struct >> hci_uart *hu, unsigned int speed) >> hci_uart_set_baudrate(hu, speed); >> } >> >> -static int qca_send_power_pulse(struct hci_dev *hdev, u8 cmd) >> +static int qca_send_power_pulse(struct hci_uart *hu, u8 cmd) >> { >> - struct hci_uart *hu = hci_get_drvdata(hdev); >> - struct qca_data *qca = hu->priv; >> - struct sk_buff *skb; >> + int ret; >> >> /* These power pulses are single byte command which are sent >> * at required baudrate to wcn3990. On wcn3990, we have an external >> @@ -1029,19 +1027,17 @@ static int qca_send_power_pulse(struct hci_dev >> *hdev, u8 cmd) >> * save power. Disabling hardware flow control is mandatory while >> * sending power pulses to SoC. >> */ >> - bt_dev_dbg(hdev, "sending power pulse %02x to SoC", cmd); >> - >> - skb = bt_skb_alloc(sizeof(cmd), GFP_KERNEL); >> - if (!skb) >> - return -ENOMEM; >> - >> + serdev_device_write_flush(hu->serdev); >> + bt_dev_dbg(hu->hdev, "sending power pulse %02x to SoC", cmd); > > nit: why clutter the code flow by putting the log statement in the > middle of code that is actually doing something with the serial > interface? > > In case you respin anyway I suggest to structure it like this: > > bt_dev_dbg(hu->hdev, "sending power pulse %02x to SoC", cmd); > > hci_uart_set_flow_control(hu, true); > serdev_device_write_flush(hu->serdev); > ret = serdev_device_write_buf(hu->serdev, &cmd, sizeof(cmd)); > > >> hci_uart_set_flow_control(hu, true); >> + ret = serdev_device_write_buf(hu->serdev, &cmd, sizeof(cmd)); >> + if (ret < 0) { >> + bt_dev_err(hu->hdev, "failed to send power pulse %02x to SoC", > > nit: especially on 'embedded' devices 'SoC' is typically associated > with the CPU running Linux, you might want to change it to > 'controller'. >
[Bala]: will update.
>> + cmd); >> + return ret; >> + } >> >> - skb_put_u8(skb, cmd); >> - hci_skb_pkt_type(skb) = HCI_COMMAND_PKT; >> - >> - skb_queue_tail(&qca->txq, skb); >> - hci_uart_tx_wakeup(hu); >> + serdev_device_wait_until_sent(hu->serdev, 0); >> >> /* Wait for 100 uS for SoC to settle down */ >> usleep_range(100, 200); > > I said earlier the delay here should be enough to ensure that the byte > gets transferred from a hardware buffer/FIFO to the controller, > however that didn't take into account that the power pulses are sent > with a baudrate of 2400. That translates to ~240 bytes/s, hence a > delay of 5 ms is needed to be on the safe side. >
[Bala]: sure will update the delay of 5 ms.
> In case you change the delay please also update the comment to make > clear this is not only time for the BT controller to settle, but also > to guarantee that the command was actually sent to the controller. >
[Bala]: will update the comment.
> So far it seems no problems have been observed, though this could be > thanks to the 100 ms delay in qca_wcn3990_init(). > > Cheers > > Matthias
-- Regards Balakrishna.
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