linux-kernel - Re: [PATCH v1 3/3] Bluetooth: hci_qca: WAR to handle WCN6750 HW issue

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Message-ID: <CABmPvSFiAC474WthmMX0nE20UEOxUD5dEYBVbiKh7HOovCnCkA@mail.gmail.com>
Date:   Mon, 9 May 2022 20:17:13 -0700
From:   Miao-chen Chou <mcchou@...omium.org>
To:     "Balakrishna Godavarthi (QUIC)" <quic_bgodavar@...cinc.com>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Andy Gross <agross@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        "mka@...omium.org" <mka@...omium.org>,
        "linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>,
        "Hemant Gupta (QUIC)" <quic_hemantg@...cinc.com>,
        "Sai Teja Aluvala (Temp) (QUIC)" <quic_saluvala@...cinc.com>,
        quic_rjliao <quic_rjliao@...cinc.com>,
        Alain Michaud <alainmichaud@...gle.com>,
        Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
Subject: Re: [PATCH v1 3/3] Bluetooth: hci_qca: WAR to handle WCN6750 HW issue

Hi Bala,

When is the estimated start date and timeline of the driver development?

Thanks,
Miao

On Fri, Apr 29, 2022 at 8:09 PM Balakrishna Godavarthi (QUIC)
<quic_bgodavar@...cinc.com> wrote:
>
> Hi Marcel,
>
> -----Original Message-----
> From: Marcel Holtmann <marcel@...tmann.org>
> Sent: Friday, April 29, 2022 8:24 PM
> To: Balakrishna Godavarthi (QUIC) <quic_bgodavar@...cinc.com>
> Cc: Andy Gross <agross@...nel.org>; robh+dt@...nel.org; bjorn.andersson@...aro.org; linux-arm-msm@...r.kernel.org; devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; Johan Hedberg <johan.hedberg@...il.com>; mka@...omium.org; linux-bluetooth@...r.kernel.org; Hemant Gupta (QUIC) <quic_hemantg@...cinc.com>; Sai Teja Aluvala (Temp) (QUIC) <quic_saluvala@...cinc.com>; quic_rjliao <quic_rjliao@...cinc.com>; mcchou@...omium.org
> Subject: Re: [PATCH v1 3/3] Bluetooth: hci_qca: WAR to handle WCN6750 HW issue
>
> Hi Balakrishna,
>
> > The patch is workaround for hardware issue on WCN6750.
> > On WCN6750 sometimes observed AON power source takes 100ms time to
> > fully discharge voltage during OFF. As WCN6750 is combo chip for WLAN
> > and BT. If any of the tech area ON is triggered during discharge
> > phase, it fails to turn ON.
> > To overcome this hardware issue, During BT ON, driver check for
> > WLAN_EN pin status. If it high, it will pull BT_EN to high immediately
> > else it will wait for 100ms assuming WLAN was just powered OFF and
> > then BT_EN will be pulled to high.
> >
> > Fixes: d8f97da1b92d2 ("Bluetooth: hci_qca: Add support for QTI
> > Bluetooth chip wcn6750")
> > Reviewed-by: Miao-chen Chou <mcchou@...omium.org>
> > Signed-off-by: Sai Teja Aluvala <quic_saluvala@...cinc.com>
> > Signed-off-by: Balakrishna Godavarthi <quic_bgodavar@...cinc.com>
> > ---
> > drivers/bluetooth/hci_qca.c | 30 ++++++++++++++++++++++++------
> > 1 file changed, 24 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
> > 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 something 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 listens to review comments these days. It is just hacking patches together to get 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 development work.
> In mean to stop stability or functional issues we are trying to add these HACKs in QCA driver.
>
> Regards
>
> Marcel
>