linux-kernel - Re: [PATCH v1] Bluetooth: hci_qca: Update baudrate change wait time for wcn3990

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Date:   Wed, 20 Feb 2019 15:43:02 -0800
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Balakrishna Godavarthi <bgodavar@...eaurora.org>
Cc:     marcel@...tmann.org, johan.hedberg@...il.com,
        linux-kernel@...r.kernel.org, linux-bluetooth@...r.kernel.org,
        hemantg@...eaurora.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v1] Bluetooth: hci_qca: Update baudrate change wait time
 for wcn3990

Hi Balakrishna,

On Wed, Feb 20, 2019 at 04:55:16PM +0530, Balakrishna Godavarthi wrote:
> This patch will update the baudrate change request wait time from
> 300 ms to 100 ms. When host sends the change baudrate request to
> the controller, controller sets its clock and wait until the
> clocks settle down. Here the Wait time is required for both
> host and controller to be on sync.
> 
> Signed-off-by: Balakrishna Godavarthi <bgodavar@...eaurora.org>
> ---
>  drivers/bluetooth/hci_qca.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index 5e03504c4e0c..22f3c983f868 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -59,7 +59,8 @@
>  
>  #define IBS_WAKE_RETRANS_TIMEOUT_MS	100
>  #define IBS_TX_IDLE_TIMEOUT_MS		2000
> -#define BAUDRATE_SETTLE_TIMEOUT_MS	300
> +#define ROME_BD_SETTLE_TIMEOUT_MS	300
> +#define WCN3990_BD_SETTLE_TIMEOUT_MS	100

nit: _BR_ instead of _BD_?

>  #define POWER_PULSE_TRANS_TIMEOUT_MS	100
>  
>  /* susclk rate */
> @@ -965,8 +966,11 @@ static int qca_set_baudrate(struct hci_dev *hdev, uint8_t baudrate)
>  	struct hci_uart *hu = hci_get_drvdata(hdev);
>  	struct qca_data *qca = hu->priv;
>  	struct sk_buff *skb;
> +	struct qca_serdev *qcadev;
> +	unsigned int bd_settling_timeout;

nit: from the context the purpose of the variable is fairly clear,
calling it just 'timeout' (or 'settling_time', it's not really a
timeout) should be fine.

That said, I have a similar change in my pipeline, which further
reduces the time to the 'strictly necessary'. It's slightly more code
though. I guess I'll send it and we can discuss/let Marcel decide
what to adopt.

Cheers

Matthias