Re: [PATCH v9 4/7] Bluetooth: hci_qca: Add wrapper functions for setting UART speed

[Matthias Kaehlcke <mka@chromium.org>]

On Thu, Jul 05, 2018 at 10:25:12PM +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 v9:
>     * added corner case to fail driver if speeds are missing.
> 
> Changes in v8:
>     * common function to set INIT and operating speeds.
> 
> Changes in v7:
>     * initial patch
>     * created wrapper functions for init and operating speeds.
> ---
>  drivers/bluetooth/hci_qca.c | 94 ++++++++++++++++++++++++++++---------
>  1 file changed, 71 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index c02e1d465cca..9106547324fa 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 +928,62 @@ 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_check_speeds(struct hci_uart *hu)
> +{
> +	/* One or the other speeds should be non zero. */
> +	if (!qca_get_speed(hu, QCA_INIT_SPEED) &&
> +	    !qca_get_speed(hu, QCA_OPER_SPEED))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +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);

mega-nit: for consistency with the 'else' branch you could return if
'speed == 0'. Not important though, feel free to ignore.

> +	} else {
> +		speed = qca_get_speed(hu, QCA_OPER_SPEED);
> +		if (!speed)
> +			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)
> +			return ret;
> +
> +		host_set_baudrate(hu, speed);
> +	}
> +
> +	return 0;
> +}
> +
>  static int qca_setup(struct hci_uart *hu)
>  {
>  	struct hci_dev *hdev = hu->hdev;
> @@ -933,37 +994,24 @@ static int qca_setup(struct hci_uart *hu)
>  
>  	bt_dev_info(hdev, "ROME setup");
>  
> +	ret = qca_check_speeds(hu);
> +	if (ret)
> +		return ret;
> +
>  	/* Patch downloading has to be done without IBS mode */
>  	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;
> -
> +	speed = qca_get_speed(hu, QCA_OPER_SPEED);
>  	if (speed) {
> -		qca_baudrate = qca_get_baudrate_value(speed);
> -
> -		bt_dev_info(hdev, "Set UART speed to %d", speed);
> -		ret = qca_set_baudrate(hdev, qca_baudrate);
> -		if (ret) {
> -			bt_dev_err(hdev, "Failed to change the baud rate (%d)",
> -				   ret);
> +		ret = qca_set_speed(hu, QCA_OPER_SPEED);
> +		if (ret)
>  			return ret;
> -		}
> -		host_set_baudrate(hu, speed);
> +
> +		qca_baudrate = qca_get_baudrate_value(speed);
>  	}

One doubt, the outcome of this change is:

	qca_set_speed(hu, QCA_INIT_SPEED);

	/* Setup user speed if needed */
	speed = qca_get_speed(hu, QCA_OPER_SPEED);
	if (speed) {
		ret = qca_set_speed(hu, QCA_OPER_SPEED);
		if (ret)
			return ret;

		qca_baudrate = qca_get_baudrate_value(speed);
	}

So we set the init speed and then directly switch to operating speed
if it is defined.

Couldn't we do this instead:

	/* Setup user speed if needed */
	speed = qca_get_speed(hu, QCA_OPER_SPEED);
	if (speed) {
		ret = qca_set_speed(hu, QCA_OPER_SPEED);
		if (ret)
			return ret;

		qca_baudrate = qca_get_baudrate_value(speed);
	} else {
	       qca_set_speed(hu, QCA_INIT_SPEED);
	}

?

Or is setting the init speed needed before the operating speed can be
set? Sorry if we discussed this earlier in this series, I know I had a
few doubts about the speed management but don't recall this one
specifically.

Other than that:

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>