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SubjectRe: [PATCH v1 1/4] Bluetooth: hci_qca: use wait_until_sent() for power pulses
On Thu, Nov 15, 2018 at 08:04:29PM +0530, Balakrishna Godavarthi wrote:
> 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.

No, serdev_device_write_wakeup() needs to be called from the serdev
driver's write_wakeup() callback (as defined in struct struct
serdev_device_ops).

Either use serdev_device_write_wakeup() as the callback, or call it from
your driver's custom write_wakeup() callback.

Hmm, I see now that the callbacks are set in hci_uart_register_device()
to hci_serdev_client_ops, which is shared by all serdev BT drivers. You
may be able to just add the call to the callback defined there so that
all Bluetooth drivers can use serdev_device_write().

Johan

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