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From:   "Balakrishna Godavarthi (QUIC)" <quic_bgodavar@quicinc.com>
To:     Marcel Holtmann <marcel@holtmann.org>,
        "Balakrishna Godavarthi (QUIC)" <quic_bgodavar@quicinc.com>
CC:     Andy Gross <agross@kernel.org>,
        "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
        "linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        "mka@chromium.org" <mka@chromium.org>,
        "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>,
        "Hemant Gupta (QUIC)" <quic_hemantg@quicinc.com>,
        "Sai Teja Aluvala (Temp) (QUIC)" <quic_saluvala@quicinc.com>,
        quic_rjliao <quic_rjliao@quicinc.com>,
        "mcchou@chromium.org" <mcchou@chromium.org>
Subject: RE: [PATCH v1 3/3] Bluetooth: hci_qca: WAR to handle WCN6750 HW issue
Thread-Topic: [PATCH v1 3/3] Bluetooth: hci_qca: WAR to handle WCN6750 HW
 issue
Thread-Index: AQHYW7ySCA0NvGHfjEC8q8sCBgrRua0G+o+AgADNSyA=
Date:   Sat, 30 Apr 2022 03:09:14 +0000
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Hi Marcel,

-----Original Message-----
From: Marcel Holtmann <marcel@holtmann.org>=20
Sent: Friday, April 29, 2022 8:24 PM
To: Balakrishna Godavarthi (QUIC) <quic_bgodavar@quicinc.com>
Cc: Andy Gross <agross@kernel.org>; robh+dt@kernel.org; bjorn.andersson@lin=
aro.org; linux-arm-msm@vger.kernel.org; devicetree@vger.kernel.org; linux-k=
ernel@vger.kernel.org; Johan Hedberg <johan.hedberg@gmail.com>; mka@chromiu=
m.org; linux-bluetooth@vger.kernel.org; Hemant Gupta (QUIC) <quic_hemantg@q=
uicinc.com>; Sai Teja Aluvala (Temp) (QUIC) <quic_saluvala@quicinc.com>; qu=
ic_rjliao <quic_rjliao@quicinc.com>; mcchou@chromium.org
Subject: Re: [PATCH v1 3/3] Bluetooth: hci_qca: WAR to handle WCN6750 HW is=
sue

Hi Balakrishna,

> The patch is workaround for hardware issue on WCN6750.
> On WCN6750 sometimes observed AON power source takes 100ms time to=20
> fully discharge voltage during OFF. As WCN6750 is combo chip for WLAN=20
> and BT. If any of the tech area ON is triggered during discharge=20
> phase, it fails to turn ON.
> To overcome this hardware issue, During BT ON, driver check for=20
> WLAN_EN pin status. If it high, it will pull BT_EN to high immediately=20
> else it will wait for 100ms assuming WLAN was just powered OFF and=20
> then BT_EN will be pulled to high.
>=20
> Fixes: d8f97da1b92d2 ("Bluetooth: hci_qca: Add support for QTI=20
> Bluetooth chip wcn6750")
> Reviewed-by: Miao-chen Chou <mcchou@chromium.org>
> Signed-off-by: Sai Teja Aluvala <quic_saluvala@quicinc.com>
> Signed-off-by: Balakrishna Godavarthi <quic_bgodavar@quicinc.com>
> ---
> drivers/bluetooth/hci_qca.c | 30 ++++++++++++++++++++++++------
> 1 file changed, 24 insertions(+), 6 deletions(-)
>=20
> diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c=20
> index eab34e2..c3862d1 100644
> --- a/drivers/bluetooth/hci_qca.c
> +++ b/drivers/bluetooth/hci_qca.c
> @@ -219,6 +219,7 @@ struct qca_serdev {
> 	struct hci_uart	 serdev_hu;
> 	struct gpio_desc *bt_en;
> 	struct gpio_desc *sw_ctrl;
> +	struct gpio_desc *wlan_en;
> 	struct clk	 *susclk;
> 	enum qca_btsoc_type btsoc_type;
> 	struct qca_power *bt_power;

I am really against these intermixing of Bluetooth and WiFi details. There =
is work ongoing to do some sequence power procedure. Maybe that is somethin=
g you should look into. This is a mess.

And again, we are still hacking around hci_qca.c instead of writing a clean=
 serdev only driver for this hardware. I have the feeling that nobody liste=
ns to review comments these days. It is just hacking patches together to ge=
t hardware enabled somehow and then disappear.

[Bala]: We are working on serdev like driver for our QCA platform.  We are =
in initial stages of discussion, and soon we will start the driver developm=
ent work.=20
In mean to stop stability or functional issues we are trying to add these H=
ACKs in QCA driver.

Regards

Marcel