Re: [PATCH v8 4/7] Bluetooth: hci_qca: Add wrapper functions for setting UART speed

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Hi Matthias,

On 2018-06-26 05:13, 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:
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 <bgodavar@xxxxxxxxxxxxxx>
---
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?

[Bala]: yes in hci_uart_setup()(hci_serdev.c) function before calling qca_setup(). we actually set baudrate, but int above code missed to restrict the further call to qca_setup() if speed =0. so we are checking the same in the qca_setup().. i.e. qca_get_speed().


+		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?


[Bala]: this patch is for rome where flow control is not used.
after we integrate wcn3990, flow control is hidden in the qca_set_speed()
        Pls check [v8 7/7] patch.

+
 static int qca_setup(struct hci_uart *hu)
 {
 	struct hci_dev *hdev = hu->hdev;
@@ -937,35 +996,17 @@ static int qca_setup(struct hci_uart *hu)
 	clear_bit(STATE_IN_BAND_SLEEP_ENABLED, &qca->flags);

 	/* Setup initial baudrate */
-	speed = 0;
-	if (hu->init_speed)
-		speed = hu->init_speed;
-	else if (hu->proto->init_speed)
-		speed = hu->proto->init_speed;
-
-	if (speed)
-		host_set_baudrate(hu, speed);
+	qca_set_speed(hu, QCA_INIT_SPEED);

 	/* Setup user speed if needed */
-	speed = 0;
-	if (hu->oper_speed)
-		speed = hu->oper_speed;
-	else if (hu->proto->oper_speed)
-		speed = hu->proto->oper_speed;
+	ret = qca_set_speed(hu, QCA_OPER_SPEED);
+	if (ret)
+		return ret;

-	if (speed) {
+	speed = qca_get_speed(hu, QCA_OPER_SPEED);
+	if (speed)
 		qca_baudrate = qca_get_baudrate_value(speed);

Is the check here necessary? qca_get_baudrate_value() returns
QCA_BAUDRATE_115200 for a zero speed.

this if for no zero operating speed,

--
Regards
Balakrishna.
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