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Message-ID: <e20781ea-09ba-2190-7318-dc62e713302d@linaro.org>
Date:   Thu, 27 Jul 2023 10:50:29 +0200
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Subject: Re: [PATCH v2 4/6] arm64: dts: qcom: Add base SM4450 QRD DTS
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To:     Tengfei Fan <quic_tengfan@quicinc.com>, andersson@kernel.org,
        konrad.dybcio@linaro.org, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org
Cc:     quic_tsoni@quicinc.com, quic_shashim@quicinc.com,
        quic_kaushalk@quicinc.com, quic_tdas@quicinc.com,
        quic_tingweiz@quicinc.com, quic_aiquny@quicinc.com,
        kernel@quicinc.com, linux-arm-msm@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20230727023508.18002-1-quic_tengfan@quicinc.com>
 <20230727023508.18002-5-quic_tengfan@quicinc.com>
 <f974f48a-05b0-530d-25a0-7ccf1b1ad113@linaro.org>
 <dba27a60-8681-e2e7-b89f-608bfbc05e93@quicinc.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
In-Reply-To: <dba27a60-8681-e2e7-b89f-608bfbc05e93@quicinc.com>
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On 27/07/2023 10:27, Tengfei Fan wrote:
> 
> 
> 在 7/27/2023 2:56 PM, Krzysztof Kozlowski 写道:
>> On 27/07/2023 04:35, Tengfei Fan wrote:
>>> Add DTS for Qualcomm QRD platform which uses SM4450 SoC.
>>>
>>> Signed-off-by: Tengfei Fan <quic_tengfan@quicinc.com>
>>> ---
>>>   arch/arm64/boot/dts/qcom/Makefile       |  1 +
>>>   arch/arm64/boot/dts/qcom/sm4450-qrd.dts | 18 ++++++++++++++++++
>>>   2 files changed, 19 insertions(+)
>>>   create mode 100644 arch/arm64/boot/dts/qcom/sm4450-qrd.dts
>>>
>>> diff --git a/arch/arm64/boot/dts/qcom/Makefile b/arch/arm64/boot/dts/qcom/Makefile
>>> index 337abc4ceb17..db805d0929c8 100644
>>> --- a/arch/arm64/boot/dts/qcom/Makefile
>>> +++ b/arch/arm64/boot/dts/qcom/Makefile
>>> @@ -186,6 +186,7 @@ dtb-$(CONFIG_ARCH_QCOM)	+= sdm850-lenovo-yoga-c630.dtb
>>>   dtb-$(CONFIG_ARCH_QCOM)	+= sdm850-samsung-w737.dtb
>>>   dtb-$(CONFIG_ARCH_QCOM)	+= sdx75-idp.dtb
>>>   dtb-$(CONFIG_ARCH_QCOM)	+= sm4250-oneplus-billie2.dtb
>>> +dtb-$(CONFIG_ARCH_QCOM)	+= sm4450-qrd.dtb
>>>   dtb-$(CONFIG_ARCH_QCOM)	+= sm6115-fxtec-pro1x.dtb
>>>   dtb-$(CONFIG_ARCH_QCOM)	+= sm6115p-lenovo-j606f.dtb
>>>   dtb-$(CONFIG_ARCH_QCOM)	+= sm6125-sony-xperia-seine-pdx201.dtb
>>> diff --git a/arch/arm64/boot/dts/qcom/sm4450-qrd.dts b/arch/arm64/boot/dts/qcom/sm4450-qrd.dts
>>> new file mode 100644
>>> index 000000000000..04ad1dd4285a
>>> --- /dev/null
>>> +++ b/arch/arm64/boot/dts/qcom/sm4450-qrd.dts
>>> @@ -0,0 +1,18 @@
>>> +// SPDX-License-Identifier: BSD-3-Clause
>>> +/*
>>> + * Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights reserved.
>>> + */
>>> +
>>> +/dts-v1/;
>>> +
>>> +#include "sm4450.dtsi"
>>> +/ {
>>> +	model = "Qualcomm Technologies, Inc. SM4450 QRD";
>>> +	compatible = "qcom,sm4450-qrd", "qcom,sm4450";
>>> +
>>> +	aliases { };
>>> +
>>> +	chosen {
>>> +		bootargs = "console=hvc0 earlycon=hvc0 hvc_dcc.enable=1 cpuidle.off=1";
>>
>> No earlycon, no hvc.enable (there is no such parameter), no cpuidle.off
>> (again don't add fake stuff). So the only suitable argument is console,
>> but this should be actually used via stdout path, although it seems
>> there is no device node for such usage?
> Hi Krzysztof,
> Checked upstream linux kernel code, there is not "hvc_dcc.enable", but 
> have other parameters, like earlycon, cpuidle.off.
> Do you mean we should not set "earlycon=hvc0 cpuidle.off=1" parameters, 

Of course not. Why production code would have earlycon? This is debug
argument, not suitable for each user of this DTS.

cpuidle.off is neither explained nor needed. Otherwise please add a
comment why this is part of hardware description.

> right? only need: bootargs = "console=hvc0" ?

You should use stdout-path if possible. If not, then only console.

Best regards,
Krzysztof