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SubjectRe: [PATCH v8 1/3] Bluetooth: hci_qca: use wait_until_sent() for power pulses
On 2019-01-17 21:43, Johan Hovold wrote:
> On Thu, Jan 17, 2019 at 03:55:17PM +0530, Balakrishna Godavarthi wrote:
>> Hi Matthias,
>>
>> On 2019-01-17 01:52, Matthias Kaehlcke wrote:
>
>> >> - /* Wait for 100 uS for SoC to settle down */
>> >> - usleep_range(100, 200);
>> >> + serdev_device_wait_until_sent(hu->serdev, timeout);
>> >> + /* Wait of 5ms is required for assuring to send the byte on the Tx
>> >> + * line and also for the controller to settle down for the received
>> >> + * byte.
>> >> + */
>> >> + usleep_range(5000, 6000);
>> >
>> > I incorrectly claimed that there might be still bytes sitting in the
>> > UART FIFO when serdev_device_wait_until_sent() returns, Johan
>> > corrected me on that (thanks!). So if it takes the SoC 100us to settle
>> > down we should be good with the original code.
>>
>> [Bala]: sure will revert, i think he commented that wait_until_sent()
>> will only guarantee circular buffer is empty. if wait_until_sent()
>> guarantee us that the data was transmitted from the FIFO, then 100us
>> will work.
>
> No, Matthias is correct; I claimed that the UART FIFO will be empty (at
> least as long as flow control is disabled, otherwise it may never empty
> and we therefore also have a time out).
>
> Johan

[Bala]: Thanks Johan for clarification.
--
Regards
Balakrishna.

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