From: Johan Hovold <johan@kernel.org>
To: Balakrishna Godavarthi <bgodavar@codeaurora.org>
Cc: Johan Hovold <johan@kernel.org>,
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: Wed, 12 Dec 2018 17:42:51 +0100 [thread overview]
Message-ID: <20181212164251.GI3500@localhost> (raw)
In-Reply-To: <c9bcbaed89a18499fe42463b20367499@codeaurora.org>
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
next prev parent reply other threads:[~2018-12-12 16:42 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 [this message]
2018-12-14 12:32 ` Balakrishna Godavarthi
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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