linux-kernel - Re: [PATCH] arm64: dts: rockchip: fix eMMC corruption on NanoPC-T6 with A3A444 chips

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Message-ID: <047fe2b8-0f94-0f0f-5964-b65844834706@manjaro.org>
Date: Sun, 19 Oct 2025 20:09:59 +0200
From: "Dragan Simic" <dsimic@...jaro.org>
To: "Anand Moon" <linux.amoon@...il.com>
Cc: "Hugh Cole-Baker" <sigmaris@...il.com>, "Jimmy Hon" <honyuenkwun@...il.com>, "Tianling Shen" <cnsztl@...il.com>, "Rob Herring" <robh@...nel.org>, "Krzysztof Kozlowski" <krzk+dt@...nel.org>, "Conor Dooley" <conor+dt@...nel.org>, "Heiko Stuebner" <heiko@...ech.de>, "Grzegorz Sterniczuk" <grzegorz@...rnicz.uk>, "Jonas Karlman" <jonas@...boo.se>, devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: rockchip: fix eMMC corruption on NanoPC-T6 with A3A444 chips

Hello Anand,

On Sunday, October 19, 2025 19:25 CEST, Anand Moon <linux.amoon@...il.com> wrote:
> Would you consider the following patch?
> 
> As per the Rockchip RK3588S SoC Technical Reference Manual (TRM) Part 1,
> chapter 21.6, Interface Description, the eMMC signals require careful handling
> to ensure signal integrity.
> 
> I2C2_SCL_M2 I/O EMMC_RSTN/I2C2_SCL_M2/UART5_RTSN_M1/GPIO2_A3_d
> BUS_IOC_GPIO2A_IOMUX_SEL_L[15:12]=0x9
> I2C2_SDA_M2 I/O EMMC_DATA_STROBE/I2C2_SDA_M2/UART5_CTSN_M1/GPIO2_A2_d
> BUS_IOC_GPIO2A_IOMUX_SEL_L[11:8]=0x9
> 
> $ git diff .
> diff --git a/arch/arm64/boot/dts/rockchip/rk3588-base-pinctrl.dtsi
> b/arch/arm64/boot/dts/rockchip/rk3588-base-pinctrl.dtsi
> index 6584d73660f6..f60a1d8be0ef 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3588-base-pinctrl.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3588-base-pinctrl.dtsi
> @@ -327,7 +327,7 @@ emmc {
>                 emmc_rstnout: emmc-rstnout {
>                         rockchip,pins =
>                                 /* emmc_rstn */
> -                               <2 RK_PA3 1 &pcfg_pull_none>;
> +                               <2 RK_PA3 1 &pcfg_pull_down_drv_level_2>;
>                 };
> 
>                 /omit-if-no-ref/
> @@ -369,7 +369,7 @@ emmc_cmd: emmc-cmd {
>                 emmc_data_strobe: emmc-data-strobe {
>                         rockchip,pins =
>                                 /* emmc_data_strobe */
> -                               <2 RK_PA2 1 &pcfg_pull_down>;
> +                               <2 RK_PA2 1 &pcfg_pull_down_drv_level_2>;
>                 };
>         };

Frankly, I'm not really sure how would such changes do something
good regarding the eMMC signal integrity?  In general, signal
integrity depends mostly on the routing of the PCB traces, which
is purely hardware design.  Sure, termination of data lines also
plays a significant role, but that surely isn't at play here.

Moreover, the eMMC RSTn line is already pulled high to VCCIO in
the reference RK3588 design, so pulling it down in the SoC itself
would be pretty much wrong thing to do.