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Date:   Thu, 07 Mar 2019 14:52:49 +0800
From:   rjliao@codeaurora.org
To:     Balakrishna Godavarthi <bgodavar@codeaurora.org>
Cc:     Stephen Boyd <swboyd@chromium.org>, johan.hedberg@gmail.com,
        marcel@holtmann.org, mka@chromium.org,
        linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org,
        hemantg@codeaurora.org, linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH v1] Bluetooth: hci_qca: Give enough time to ROME
 controller to bootup.
In-Reply-To: <a22894cea091ee9945af9c22d6e42051@codeaurora.org>
References: <20190306162113.8585-1-bgodavar@codeaurora.org>
 <155191158734.20095.15990837191526416248@swboyd.mtv.corp.google.com>
 <a22894cea091ee9945af9c22d6e42051@codeaurora.org>
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在 2019-03-07 14:49，Balakrishna Godavarthi 写道：
> Hi Stepen,
> 
> On 2019-03-07 04:03, Stephen Boyd wrote:
>> 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@codeaurora.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?
>> 
> [Bala]: this was observed in our stress testing and even the CHIP 
> firmware team
>         confirmed that BT chip required at least 150 ms to boot up.
> 
> @Rocky to confirm my statement.
> 
>>>  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;

Yes,ROME firmware needs 150ms to boot up after toggle the BT_EN pin.