linux-kernel - Re: [PATCH v1] Bluetooth: hci_qca: Give enough time to ROME controller to bootup.

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Date:   Wed, 06 Mar 2019 14:33:07 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Balakrishna Godavarthi <bgodavar@...eaurora.org>,
        johan.hedberg@...il.com, marcel@...tmann.org
Cc:     mka@...omium.org, linux-kernel@...r.kernel.org,
        linux-bluetooth@...r.kernel.org, hemantg@...eaurora.org,
        linux-arm-msm@...r.kernel.org, rjliao@...eaurora.org,
        Balakrishna Godavarthi <bgodavar@...eaurora.org>
Subject: Re: [PATCH v1] Bluetooth: hci_qca: Give enough time to ROME controller to bootup.

Quoting Balakrishna Godavarthi (2019-03-06 08:21:13)
> This patch enables enough time to ROME controller to bootup
> after we bring the enable ping out of reset.
> 
> Signed-off-by: Balakrishna Godavarthi <bgodavar@...eaurora.org>
> ---

Any Fixes tag? And maybe some more explanation or background on where
150 ms sleep comes from would be useful. Was it determined
experimentally or did it come from a datasheet somewhere? Does the time
differ between boards?

>  drivers/bluetooth/hci_qca.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> index 237aea34b69f..1953b13511e7 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -508,6 +508,8 @@ static int qca_open(struct hci_uart *hu)
>                 qcadev = serdev_device_get_drvdata(hu->serdev);
>                 if (qcadev->btsoc_type != QCA_WCN3990) {
>                         gpiod_set_value_cansleep(qcadev->bt_en, 1);
> +                       /* Controller needs time to bootup. */
> +                       msleep(150);
>                 } else {
>                         hu->init_speed = qcadev->init_speed;
>                         hu->oper_speed = qcadev->oper_speed;