linux-kernel - Re: [PATCH 2/5] arm64: dts: qcom: lemans: Add SDHC controller and SDC pin configuration

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Message-ID: <3b691f3a-633c-4a7f-bc38-a9c464d83fe1@oss.qualcomm.com>
Date: Thu, 4 Sep 2025 16:34:05 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
        Wasim Nazir <wasim.nazir@....qualcomm.com>
Cc: 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>,
        Richard Cochran <richardcochran@...il.com>, kernel@....qualcomm.com,
        linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        netdev@...r.kernel.org, Monish Chunara <quic_mchunara@...cinc.com>
Subject: Re: [PATCH 2/5] arm64: dts: qcom: lemans: Add SDHC controller and SDC
 pin configuration

On 9/4/25 3:35 PM, Dmitry Baryshkov wrote:
> On Wed, Sep 03, 2025 at 09:58:33PM +0530, Wasim Nazir wrote:
>> On Wed, Sep 03, 2025 at 06:12:59PM +0200, Konrad Dybcio wrote:
>>> On 8/27/25 3:20 AM, Dmitry Baryshkov wrote:
>>>> On Tue, Aug 26, 2025 at 11:51:01PM +0530, Wasim Nazir wrote:
>>>>> From: Monish Chunara <quic_mchunara@...cinc.com>
>>>>>
>>>>> Introduce the SDHC v5 controller node for the Lemans platform.
>>>>> This controller supports either eMMC or SD-card, but only one
>>>>> can be active at a time. SD-card is the preferred configuration
>>>>> on Lemans targets, so describe this controller.
>>>>>
>>>>> Define the SDC interface pins including clk, cmd, and data lines
>>>>> to enable proper communication with the SDHC controller.
>>>>>
>>>>> Signed-off-by: Monish Chunara <quic_mchunara@...cinc.com>
>>>>> Co-developed-by: Wasim Nazir <wasim.nazir@....qualcomm.com>
>>>>> Signed-off-by: Wasim Nazir <wasim.nazir@....qualcomm.com>
>>>>> ---
>>>>>  arch/arm64/boot/dts/qcom/lemans.dtsi | 70 ++++++++++++++++++++++++++++++++++++
>>>>>  1 file changed, 70 insertions(+)
>>>>>
>>>>> diff --git a/arch/arm64/boot/dts/qcom/lemans.dtsi b/arch/arm64/boot/dts/qcom/lemans.dtsi
>>>>> index 99a566b42ef2..a5a3cdba47f3 100644
>>>>> --- a/arch/arm64/boot/dts/qcom/lemans.dtsi
>>>>> +++ b/arch/arm64/boot/dts/qcom/lemans.dtsi
>>>>> @@ -3834,6 +3834,36 @@ apss_tpdm2_out: endpoint {
>>>>>  			};
>>>>>  		};
>>>>>  
>>>>> +		sdhc: mmc@...4000 {
>>>>> +			compatible = "qcom,sa8775p-sdhci", "qcom,sdhci-msm-v5";
>>>>> +			reg = <0x0 0x087c4000 0x0 0x1000>;
>>>>> +
>>>>> +			interrupts = <GIC_SPI 383 IRQ_TYPE_LEVEL_HIGH>,
>>>>> +				     <GIC_SPI 521 IRQ_TYPE_LEVEL_HIGH>;
>>>>> +			interrupt-names = "hc_irq", "pwr_irq";
>>>>> +
>>>>> +			clocks = <&gcc GCC_SDCC1_AHB_CLK>,
>>>>> +				 <&gcc GCC_SDCC1_APPS_CLK>;
>>>>> +			clock-names = "iface", "core";
>>>>> +
>>>>> +			interconnects = <&aggre1_noc MASTER_SDC 0 &mc_virt SLAVE_EBI1 0>,
>>>>> +					<&gem_noc MASTER_APPSS_PROC 0 &config_noc SLAVE_SDC1 0>;
>>>>> +			interconnect-names = "sdhc-ddr", "cpu-sdhc";
>>>>> +
>>>>> +			iommus = <&apps_smmu 0x0 0x0>;
>>>>> +			dma-coherent;
>>>>> +
>>>>> +			resets = <&gcc GCC_SDCC1_BCR>;
>>>>> +
>>>>> +			no-sdio;
>>>>> +			no-mmc;
>>>>> +			bus-width = <4>;
>>>>
>>>> This is the board configuration, it should be defined in the EVK DTS.
>>>
>>> Unless the controller is actually incapable of doing non-SDCards
>>>
>>> But from the limited information I can find, this one should be able
>>> to do both
>>>
>>
>> It’s doable, but the bus width differs when this controller is used for
>> eMMC, which is supported on the Mezz board. So, it’s cleaner to define
>> only what’s needed for each specific usecase on the board.
> 
> `git grep no-sdio arch/arm64/boot/dts/qcom/` shows that we have those
> properties inside the board DT. I don't see a reason to deviate.

Just to make sure we're clear

I want the author to keep bus-width in SoC dt and move the other
properties to the board dt

Konrad