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

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Message-ID: <CANAwSgRuPhgnGy=2oY6u1jQtDRkQAdPqGv5NUNv8+WDeHq-56Q@mail.gmail.com>
Date: Mon, 20 Oct 2025 08:43:18 +0530
From: Anand Moon <linux.amoon@...il.com>
To: Dragan Simic <dsimic@...jaro.org>
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

Hi Dragan,

On Sun, 19 Oct 2025 at 23:40, Dragan Simic <dsimic@...jaro.org> wrote:
>
> 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.
>
It is necessary to enhance the signal quality from the controller to
the eMMC module

> 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.
>
It is specified in the TRM that this is only applicable during
initialization.as per my understanding.

Thanks
-Anand