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

[Balakrishna Godavarthi <bgodavar@codeaurora.org>]

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@codeaurora.org>
>> ---
>> 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.