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SubjectRe: [PATCH v1 1/4] Bluetooth: hci_qca: use wait_until_sent() for power pulses
Hi Johan,

On 2018-11-14 20:57, Johan Hovold wrote:
> On Tue, Nov 06, 2018 at 05:35:25PM +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>
>> ---
>> drivers/bluetooth/hci_qca.c | 22 +++++++++-------------
>> 1 file changed, 9 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
>> index f72ded4ec9ae..051f081d1835 100644
>> --- a/drivers/bluetooth/hci_qca.c
>> +++ b/drivers/bluetooth/hci_qca.c
>> @@ -1016,8 +1016,7 @@ static inline void host_set_baudrate(struct
>> hci_uart *hu, unsigned int speed)
>> static int qca_send_power_pulse(struct hci_dev *hdev, 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
>> @@ -1030,18 +1029,14 @@ static int qca_send_power_pulse(struct hci_dev
>> *hdev, u8 cmd)
>> * 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;
>> -
>> hci_uart_set_flow_control(hu, true);
>> + ret = serdev_device_write(hu->serdev, &cmd, sizeof(cmd), 0);
>
> Don't you want a non-zero timeout here? Otherwise you might as well
> call
> serdev_device_write() directly.
>

[Bala]: we need an in definite timeout for these commands. will use
HCI_UART_TX_WAKEUP.

> Also have you made sure that serdev_device_write_wakeup() is called in
> the drivers write-wakeup callback as serdev_device_write() requires?
>
> See this series in case what you really wanted was to wait indefinitely
> (you can use MAX_SCHEDULE_TIMEOUT):
>
> https://lkml.kernel.org/r/<20181114150904.19653-1-johan@kernel.org>
>

[Bala]: thanks for pointers. from
https://lore.kernel.org/patchwork/patch/1012358/
it was clear to me that i need call below functions in order to
wait until full data is sent.

serdev_device_write_wakeup()
serdev_device_write()
serdev_device_wait_until_sent()

correct me whether my understanding is correct.

>> + if (ret < 0) {
>> + bt_dev_err(hdev, "failed to send power pulse %02x to SoC", 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);
>> @@ -1283,7 +1278,8 @@ static void qca_power_shutdown(struct hci_uart
>> *hu)
>>
>> host_set_baudrate(hu, 2400);
>> hci_uart_set_flow_control(hu, true);
>> - serdev_device_write_buf(serdev, &cmd, sizeof(cmd));
>> + serdev_device_write(serdev, &cmd, sizeof(cmd), 0);
>
> Same here.
>
>> + serdev_device_wait_until_sent(serdev, 0);
>> hci_uart_set_flow_control(hu, false);
>> qca_power_setup(hu, false);
>> }
>
> Johan

--
Regards
Balakrishna.

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