linux-kernel - Re: [PATCH] arm64: dts: ti: k3-j721e-main: Remove ti,strobe-sel property

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Message-ID: <20221115034324.6qpxl2774bzwbl3t@acorn>
Date:   Mon, 14 Nov 2022 21:43:24 -0600
From:   Nishanth Menon <nm@...com>
To:     Bhavya Kapoor <b-kapoor@...com>
CC:     <robh+dt@...nel.org>, <krzysztof.kozlowski+dt@...aro.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <vigneshr@...com>,
        <piyali_g@...com>
Subject: Re: [PATCH] arm64: dts: ti: k3-j721e-main: Remove ti,strobe-sel
 property

On 16:52-20221107, Bhavya Kapoor wrote:
> According to latest errata of J721e [1], HS400 mode is not supported
> in MMCSD0 subsystem (i2024) .  Speed modes supported has been already
> updated in PATCH eb8f6194e807. 'ti,strobe-sel' property is only

eb8f6194e807 isn't a PATCH :) See
Documentation/process/submitting-patches.rst line 99 as an example how
to refer to specific commits.

> required by HS400 speed mode and thus needs to be removed from kernel
> dtsi for J721e soc.

s/soc/SoC

> 
> 'ti,strobe-sel' is read in sdhci_am654.c line 733 and gets stored in
> sdhci_am654->strb_sel. This sdhci_am654->strb_sel is used at only one
> place in sdhci_am654.c line 291 which will only get used if HS400
> is enabled.

Please don't describe driver behavior in device tree patch. DT binding
should indicate the property behavior.

> 
> Thus, drop 'ti,strobe-sel' property from kernel dtsi for J721e soc.
> 
> [.] https://www.ti.com/lit/er/sprz455/sprz455.pdf

Should be [1] ?

I think we could simplify it by saying that the commit that implemented
the patch missed dropping ti,strobe-sel property that is only meant for
HS400. (please rephrase appropriately).

Documentation/devicetree/bindings/mmc/sdhci-am654.yaml

Now, that said - this could be enforced in dt-schema to prevent such a
miss from taking place (if then required)

Might be a case to post a separate patch for the enforcement?

> 
> Fixes: eb8f6194e807 ("arm64: dts: ti: k3-j721e-main: Update the speed modes supported and their itap delay values for MMCSD subsystems")
> Signed-off-by: Bhavya Kapoor <b-kapoor@...com>
> ---
>  arch/arm64/boot/dts/ti/k3-j721e-main.dtsi | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
> index 917c9dc99efa..e4748a838d83 100644
> --- a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
> +++ b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
> @@ -1094,7 +1094,6 @@
>  		ti,itap-del-sel-mmc-hs = <0xa>;
>  		ti,itap-del-sel-ddr52 = <0x3>;
>  		ti,trm-icp = <0x8>;
> -		ti,strobe-sel = <0x77>;
>  		dma-coherent;
>  	};
>  
> -- 
> 2.20.1
> 

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D