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

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Message-ID: <xausmwmh6ze5374eukv6pcmwe3lv4qun73pcszd3aqgjwm75u6@h3exsqf4dsfv>
Date: Fri, 5 Sep 2025 14:45:05 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Cc: Wasim Nazir <wasim.nazir@....qualcomm.com>,
        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 Fri, Sep 05, 2025 at 01:14:29PM +0200, Konrad Dybcio wrote:
> On 9/4/25 7:32 PM, Dmitry Baryshkov wrote:
> > On Thu, Sep 04, 2025 at 04:34:05PM +0200, Konrad Dybcio wrote:
> >> 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
> > 
> > I think bus-width is also a property of the board. In the end, it's a
> > question of schematics whether we route 1 wire or all 4 wires. git-log
> > shows that bus-width is being sent in both files (and probalby we should
> > sort that out).
> 
> Actually this is the controller capability, so if it can do 8, it should
> be 8 and the MMC core will do whatever it pleases (the not-super-sure
> docs that I have say 8 for this platform)

Isn't it a physical width of the bus between the controller and the slot
or eMMC chip?

-- 
With best wishes
Dmitry