From: Balakrishna Godavarthi <bgodavar@codeaurora.org>
To: Johan Hovold <johan@kernel.org>
Cc: marcel@holtmann.org, johan.hedberg@gmail.com, mka@chromium.org,
linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org,
hemantg@codeaurora.org, linux-arm-msm@vger.kernel.org,
Johan Hovold <jhovold@gmail.com>
Subject: Re: [PATCH v3 1/4] Bluetooth: hci_qca: use wait_until_sent() for power pulses
Date: Fri, 14 Dec 2018 18:02:40 +0530 [thread overview]
Message-ID: <53775e90cb3803cee9cfff2325cb7429@codeaurora.org> (raw)
In-Reply-To: <20181212164251.GI3500@localhost>
Hi Johan,
On 2018-12-12 22:12, Johan Hovold wrote:
> On Thu, Dec 06, 2018 at 04:10:07PM +0530, Balakrishna Godavarthi wrote:
>> Hi Johan,
>>
>> On 2018-12-05 11:55, Johan Hovold wrote:
>> > On Fri, Nov 30, 2018 at 08:32:44PM +0530, Balakrishna Godavarthi wrote:
>
>> >> + ret = serdev_device_write(hu->serdev, &cmd, sizeof(cmd), 0);
>> >
>> > You're still using 0 as a timeout here which is broken, as I already
>> > told you.
>>
>> [Bala]: got the change now will update to timeout to non zero value.
>>
>> > From 4.21 this will result in an indefinite timeout, but currently
>> > implies not to wait for a full write buffer to drain at all.
>> >
>> > As I also mentioned, you need to to make sure to call
>> > serdev_device_write_wakeup() in the write_wakup() path if you are going
>> > to use serdev_device_write() at all.
>>
>> [Bala]: this where i am confused.
>> calling serdev_device_write is calling an wakeup internally.
>> below is the flow
>>
>> ttyport_write_buf:
>> * calling serdev_device_write() will call write_buf()
>> in
>> this call we are enabling bit "TTY_DO_WRITE_WAKEUP" and calling
>> write()
>> i.e. uart_write() where we call in start_tx. this
>> will
>> go to the vendor specific write where in isr we call
>> uart_write_wakeup()
>>
>> https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/qcom_geni_serial.c#L756
>>
>>
>> uart_write_wakeup()->ttyport_write_wakeup()->serdev_controller_write_wakeup()->hci_uart_write_wakeup()->hci_uart_tx_wakeup()
>>
>> the above is flow when serdev_device_write() is called, it is
>> indirectly calling serdev_write_wakeup().
>
> No, serdev_device_write_wakeup() is currently not called in this path,
> which means you cannot use serdev_device_write().
>
>> Why actual we need to call an serdev_write_wakeup() is this
>> wakeup related to the UART port or for the BT chip.
>
> serdev_device_write_wakeup() is where a writer blocked on a full write
> buffer in serdev_device_write() is woken up.
>
> Johan
Is it preferred to use and serdev_device_write_buf() followed by
serdev_device_wait_until_sent()
or do we required an write_wakeup() called before writing into
serdev_device_write_buf()
--
Regards
Balakrishna.
next prev parent reply other threads:[~2018-12-14 12:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-30 15:02 [PATCH v3 0/4] Bug fixes for Qualcomm BT chip wcn3990 Balakrishna Godavarthi
2018-11-30 15:02 ` [PATCH v3 1/4] Bluetooth: hci_qca: use wait_until_sent() for power pulses Balakrishna Godavarthi
2018-12-05 6:25 ` Johan Hovold
2018-12-06 10:40 ` Balakrishna Godavarthi
2018-12-11 15:42 ` Balakrishna Godavarthi
2018-12-12 16:42 ` Johan Hovold
2018-12-14 12:32 ` Balakrishna Godavarthi [this message]
2018-12-14 13:16 ` Johan Hovold
2018-12-14 13:41 ` Balakrishna Godavarthi
2018-11-30 15:02 ` [PATCH v3 2/4] Bluetooth: hci_qca: Deassert RTS while baudrate change command Balakrishna Godavarthi
2018-11-30 15:02 ` [PATCH v3 3/4] Bluetooth: hci_qca: Fix frame reassembly errors for wcn3990 Balakrishna Godavarthi
2018-11-30 15:02 ` [PATCH v3 4/4] Bluetooth: hci_qca: Disable IBS state machine and flush Tx buffer Balakrishna Godavarthi
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