On Mon, Jun 25, 2018 at 04:43:54PM -0700, Matthias Kaehlcke wrote:

This is a nice improvement, a few remaining questions inline.

On Mon, Jun 25, 2018 at 07:10:10PM +0530, Balakrishna Godavarthi wrote:

quoted

In function qca_setup, we set initial and operating speeds for Qualcomm
Bluetooth SoC's. This block of code is common across different
Qualcomm Bluetooth SoC's. Instead of duplicating the code, created
a wrapper function to set the speeds. So that future coming SoC's
can use these wrapper functions to set speeds.

Signed-off-by: Balakrishna Godavarthi <redacted>
---
Changes in v8:
    * common function to set INIT and operating speeds.
    * moved hardware flow control to qca_set_speed().
	
Changes in v7:
    * initial patch
    * created wrapper functions for init and operating speeds.
---
 drivers/bluetooth/hci_qca.c | 89 +++++++++++++++++++++++++++----------
 1 file changed, 65 insertions(+), 24 deletions(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index fe62420ef838..38b7dbe6c897 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c

@@ -119,6 +119,11 @@ struct qca_data {
 	u64 votes_off;
 };
 
+enum qca_speed_type {
+	QCA_INIT_SPEED = 1,
+	QCA_OPER_SPEED
+};
+
 struct qca_serdev {
 	struct hci_uart	 serdev_hu;
 	struct gpio_desc *bt_en;

@@ -923,6 +928,60 @@ static inline void host_set_baudrate(struct hci_uart *hu, unsigned int speed)
 		hci_uart_set_baudrate(hu, speed);
 }
 
+static unsigned int qca_get_speed(struct hci_uart *hu,
+				  enum qca_speed_type speed_type)
+{
+	unsigned int speed = 0;
+
+	if (speed_type == QCA_INIT_SPEED) {
+		if (hu->init_speed)
+			speed = hu->init_speed;
+		else if (hu->proto->init_speed)
+			speed = hu->proto->init_speed;
+	} else {
+		if (hu->oper_speed)
+			speed = hu->oper_speed;
+		else if (hu->proto->oper_speed)
+			speed = hu->proto->oper_speed;
+	}
+
+	return speed;
+}
+
+static int qca_set_speed(struct hci_uart *hu, enum qca_speed_type speed_type)
+{
+	unsigned int speed, qca_baudrate;
+	int ret;
+
+	if (speed_type == QCA_INIT_SPEED) {
+		speed = qca_get_speed(hu, QCA_INIT_SPEED);
+		if (speed)
+			host_set_baudrate(hu, speed);
+		else
+			bt_dev_err(hu->hdev, "Init speed should be non zero");

The check for 'speed == 0' is done in multiple places. From this
code I deduce that it is expected that both INIT and OPER speed are
set to non-zero values. What happens if either of them is zero? Is the
driver still operational?

quoted

+		return 0;
+	}
+
+	speed = qca_get_speed(hu, QCA_OPER_SPEED);
+	if (!speed) {
+		bt_dev_err(hu->hdev, "operating speed should be non zero");
+		return 0;
+	}
+
+	qca_baudrate = qca_get_baudrate_value(speed);
+	bt_dev_info(hu->hdev, "Set UART speed to %d", speed);
+	ret = qca_set_baudrate(hu->hdev, qca_baudrate);
+	if (ret) {
+		bt_dev_err(hu->hdev, "Failed to change the baudrate (%d)", ret);
+		return ret;
+	}
+
+	host_set_baudrate(hu, speed);
+
+	return ret;
+}

In the discussion on "[v7,8/8] Bluetooth: hci_qca: Add support for
Qualcomm Bluetooth chip wcn3990" you mentioned the possbility to move
the hci_uart_set_flow_control() calls into _set_speed(). This seemed
interesting but finally it isn't done in this series. Did you
encounter that it is not feasible/desirable for some reason?

I got that half wrong. "[v8,7/7] Bluetooth: hci_qca: Add support for
Qualcomm Bluetooth chip wcn3990" adds the flow control calls to
_set_speed() however there are still_set_flow_control() calls in
qca_setup(), which confused/s me.

Could you provide a brief summary on the situations (relevant for this
driver) in which flow controls needs to be enabled/disabled?