linux-kernel - Re: [PATCH V4 3/4] arm64: dts: qcom: sc7180: Add sleep state for BT UART

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Date:   Thu, 10 Sep 2020 12:50:36 +0000
From:   skakit@...eaurora.org
To:     Doug Anderson <dianders@...omium.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Gross <agross@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
        Akash Asthana <akashast@...eaurora.org>,
        Roja Rani Yarubandi <rojay@...eaurora.org>,
        msavaliy@....qualcomm.com
Subject: Re: [PATCH V4 3/4] arm64: dts: qcom: sc7180: Add sleep state for BT
 UART

On 2020-09-10 02:59, Doug Anderson wrote:
> Hi,
> 
> On Thu, Sep 3, 2020 at 8:08 AM satya priya <skakit@...eaurora.org> 
> wrote:
>> 
>> diff --git a/arch/arm64/boot/dts/qcom/sc7180-idp.dts 
>> b/arch/arm64/boot/dts/qcom/sc7180-idp.dts
>> index cecac3e..77e3523 100644
>> --- a/arch/arm64/boot/dts/qcom/sc7180-idp.dts
>> +++ b/arch/arm64/boot/dts/qcom/sc7180-idp.dts
>> @@ -507,6 +507,43 @@
>>         };
>>  };
>> 
>> +&qup_uart3_sleep {
>> +       pinconf-cts {
>> +               /*
>> +                * Configure no-pull on CTS. As this is driven by BT, 
>> do not
>> +                * specify any pull in order to not conflict with BT 
>> pulls.
>> +                */
>> +               pins = "gpio38";
>> +               bias-disable;
> 
> Same comment as in the previous patch that I'm not convinced removing
> the bias here is correct.
> 

Okay.

> 
>> +       };
>> +
>> +       pinconf-rts {
>> +               /*
>> +                * Configure pull-down on RTS to make sure that the BT 
>> SoC can
>> +                * wake up the system by sending wakeup bytes during 
>> suspend.
>> +                */
>> +               pins = "gpio39";
>> +               bias-pull-down;
>> +       };
>> +
>> +       pinconf-tx {
>> +               /* Configure pull-up on TX when it isn't actively 
>> driven */
>> +               pins = "gpio40";
>> +               bias-pull-up;
>> +       };
>> +
>> +       pinconf-rx {
>> +               /*
>> +                * Configure a pull-up on RX. This is needed to avoid
>> +                * garbage data when the TX pin of the Bluetooth 
>> module is
>> +                * in tri-state (module powered off or not driving the
>> +                * signal yet).
>> +                */
>> +               pins = "gpio41";
>> +               bias-pull-up;
>> +       };
>> +};
>> +
>>  &qup_uart8_default {
> 
> Slight nit that "default" starts with a "d" which sorts before "sleep"
> which starts with an "s".  Thus "qup_uart8_default" should be above
> "qup_uart3_sleep", not below.

Okay.