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

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Message-ID: <7934659a-0f2f-4c8f-9699-f32ae0fff53c@quicinc.com>
Date: Wed, 13 Aug 2025 16:44:47 +0530
From: Sarthak Garg <quic_sartgarg@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
CC: 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>, <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 8/5/2025 3:29 PM, Dmitry Baryshkov wrote:
> On Tue, Aug 05, 2025 at 02:49:29PM +0530, Sarthak Garg wrote:
>>
>>
>> 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 ---
> 
> You missed several devices which use SM8550. Please fix that.
> 
>>>>    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?
> 
> This patch requires all previous patches to work, so it can not be
> applied in parallel. It should be applied after the previous patches are
> merged by MMC maintainers and then available in the Bjorn's tree. This
> requires either skipping a release for this patch or using an immutable
> tag for the MMC patches. All these deteails should be explained in the
> cover letter.
> 

As mentioned in reply to Krzysztof's previous comment we are planning to 
drop the plan to modify broken capabilities for SM8550 in the current 
cycle. The removal of SDR104/SDR50 caps will be revisited for upcoming 
targets, where we can ensure proper validation and alignment with MMC 
patch dependencies.

Best regards,
Sarthak