Re: [PATCH v1 1/4] Bluetooth: hci_qca: use wait_until_sent() for power pulses

From: Balakrishna Godavarthi
Date: Thu Nov 15 2018 - 09:34:39 EST


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@xxxxxxxxxxxxxx>
---
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@xxxxxxxxxx>


[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.