linux-kernel - Re: [PATCH v4 1/8] dt-bindings: serial: describe SA8255p

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Message-ID: <c839726f-6625-45b5-a632-75bd2b8dd7bb@quicinc.com>
Date: Tue, 6 May 2025 23:35:12 +0530
From: Praveen Talari <quic_ptalari@...cinc.com>
To: Krzysztof Kozlowski <krzk@...nel.org>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby
	<jirislaby@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski
	<krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson
	<andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-serial@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <psodagud@...cinc.com>, <djaggi@...cinc.com>,
        <quic_msavaliy@...cinc.com>, <quic_vtanuku@...cinc.com>,
        <quic_arandive@...cinc.com>, <quic_mnaresh@...cinc.com>,
        <quic_shazhuss@...cinc.com>, Nikunj Kela
	<quic_nkela@...cinc.com>
Subject: Re: [PATCH v4 1/8] dt-bindings: serial: describe SA8255p


On 5/6/2025 11:45 AM, Krzysztof Kozlowski wrote:
> On 05/05/2025 15:42, Praveen Talari wrote:
>> Hi Krzysztof
>>
>> On 5/5/2025 3:29 PM, Krzysztof Kozlowski wrote:
>>> On 05/05/2025 08:51, Praveen Talari wrote:
>>>>>>>> +    serial@...000 {
>>>>>>>> +        compatible = "qcom,sa8255p-geni-uart";
>>>>>>>> +        reg = <0x990000 0x4000>;
>>>>>>>> +        interrupts = <GIC_SPI 531 IRQ_TYPE_LEVEL_HIGH>;
>>>>>>> Why isn't here wakeup interrupt? Commit msg also does not help me to
>>>>>>> understand why number of interrupts varies.
>>>>>> Currently we are not using wake-irq because it is optional for our current
>>>>>> implementation.
>>>>> Great explanation. I asked why is it optional, answer because it is
>>>>> optional.
>>>> sorry.
>>>>> What does it mean optional? This is part of the SoC, so how given one,
>>>>> fixed SoC can have it routed or not routed in the same time?
>>>> the serial driver doesn't enter runtime suspend mode until the port is
>>>> closed.
>>>>
>>>> therefore, there is no need for a wake IRQ when the driver is in an
>>>> active state
>>> You described current Linux driver, so if we change Linux driver or we
>>> try for example FreeBSD, then bindings are different?
>> Currently, the driver includes code to register the device's wakeup
>> capability
>>
>> but it lacks the necessary handler code for wakeup IRQ. According to the
>> serial driver,
>>
>> the wake IRQ is meant to wake up the device but the device remains
>> active because
>>
>> the serial driver does not enter runtime suspend mode until the port
>> closed.
>>
>> So it is better to exclude the wake IRQ until the appropriate code is added.
> But my driver on FreeBSD handles the wake IRQ, why you cannot add the
> IRQ for it?

Will update in next patch set.

Thanks,

Praveen Talari

>
> Best regards,
> Krzysztof