linux-kernel - Re: [PATCH V4 4/4] arm64: dts: qcom: sm8550: Remove SDR104/SDR50 broken capabilities

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Message-ID: <c7e36755-9255-4209-9d53-20077bd1d3ba@quicinc.com>
Date: Tue, 5 Aug 2025 14:49:29 +0530
From: Sarthak Garg <quic_sartgarg@...cinc.com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
        Ulf Hansson
	<ulf.hansson@...aro.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>,
        Adrian Hunter
	<adrian.hunter@...el.com>
CC: <linux-mmc@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <quic_cang@...cinc.com>, <quic_nguyenb@...cinc.com>,
        <quic_rampraka@...cinc.com>, <quic_pragalla@...cinc.com>,
        <quic_sayalil@...cinc.com>, <quic_nitirawa@...cinc.com>,
        <quic_bhaskarv@...cinc.com>, <kernel@....qualcomm.com>
Subject: Re: [PATCH V4 4/4] arm64: dts: qcom: sm8550: Remove SDR104/SDR50
 broken capabilities



On 8/1/2025 2:32 PM, Krzysztof Kozlowski wrote:
> On 01/08/2025 10:45, Sarthak Garg wrote:
>> The kernel now handles level shifter limitations affecting SD card
>> modes, making it unnecessary to explicitly disable SDR104 and SDR50
>> capabilities in the device tree.
>>
>> However, due to board-specific hardware constraints particularly related
>> to level shifter in this case the maximum frequency for SD High-Speed
>> (HS) mode must be limited to 37.5 MHz to ensure reliable operation of SD
>> card in HS mode. This is achieved using the max-sd-hs-frequency property
>> in the board DTS.
>>
>> Signed-off-by: Sarthak Garg <quic_sartgarg@...cinc.com>
>> ---
>>   arch/arm64/boot/dts/qcom/sm8550-hdk.dts                     | 1 +
>>   arch/arm64/boot/dts/qcom/sm8550-mtp.dts                     | 1 +
>>   arch/arm64/boot/dts/qcom/sm8550-sony-xperia-yodo-pdx234.dts | 1 +
>>   arch/arm64/boot/dts/qcom/sm8550.dtsi                        | 3 ---
>>   4 files changed, 3 insertions(+), 3 deletions(-)
>>
> 
> This will break MMC for all of the users and nothing in commit msg or
> cover letter explains that or mentions merging strategy.
> 
> Exactly this case is covered by your internal guideline, no? Please read it.
> 
> Best regards,
> Krzysztof

Just to make sure I’m addressing the right concern — are you primarily 
worried about the introduction of the max-sd-hs-frequency property in 
the board DTS files, or about the removal of the sdhci-caps-mask
from the common sm8550.dtsi?