Re: [PATCH] arm64: dts: rockchip: Enable SDR104 on the ODROID-M1 SD card

From: Heiko Stuebner <heiko@sntech.de>
To: Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	iav@iav.lv
Cc: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org,
	Igor Velkov <iav@iav.lv>
Subject: Re: [PATCH] arm64: dts: rockchip: Enable SDR104 on the ODROID-M1 SD card
Date: Fri, 13 Nov 2026 21:09:01 +0100	[thread overview]
Message-ID: <ozv3Kw_6ToOMhu6IF4wDPQ@sntech.de> (raw)
In-Reply-To: <20261110-odroid-m1-sdr104-v1-1-8edc6d5c1bf6@iav.lv>

Am Dienstag, 10. November 2026, 03:50:01 Mitteleuropäische Normalzeit schrieb Igor Velkov via B4 Relay:
> From: Igor Velkov <iav@iav.lv>
> 
> The SD card already switches to 1.8 V, but only SDR50 is allowed, and
> clk_sdmmc0 on RK3568 is a mux without a divider: dw_mmc-rockchip asks
> it for twice the card clock, 200 MHz for SDR50, the mux rounds down to
> the 100 MHz parent and the card runs at 50 MHz.
> 
> Allow SDR104 instead; the MMC core still falls back to SDR50 for cards
> without SDR104. With the 150 MHz max-frequency from rk356x-base.dtsi
> the clock comes from the 300 MHz parent and the card runs at 150 MHz.
> Hardkernel's vendor kernel already uses sd-uhs-sdr104 on this board.
> With a SanDisk 128 GB card, direct read goes from 22 MB/s to
> 58-64 MB/s and direct write from 20 MB/s to 47-50 MB/s.
> 
> Signed-off-by: Igor Velkov <iav@iav.lv>
> ---
> Tested with an Armbian 7.3.3 kernel (rockchip64), the property added to
> the DTB with fdtput: reboot, sysrq-b, watchdog reset, poweroff, s2idle,
> deep, hibernate, hybrid-sleep and suspend-then-hibernate; the card
> re-tuned and came back in SDR104 at 150 MHz in all 29 runs.
> ---
>  arch/arm64/boot/dts/rockchip/rk3568-odroid-m1.dts | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3568-odroid-m1.dts b/arch/arm64/boot/dts/rockchip/rk3568-odroid-m1.dts
> index ec43dee18094..6f77e73abc8e 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3568-odroid-m1.dts
> +++ b/arch/arm64/boot/dts/rockchip/rk3568-odroid-m1.dts
> @@ -610,7 +610,7 @@ &sdmmc0 {
>  	disable-wp;
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&sdmmc0_bus4 &sdmmc0_clk &sdmmc0_cmd &sdmmc0_det>;
> -	sd-uhs-sdr50;
> +	sd-uhs-sdr104;

You then want both of them in the file.
The devicetree does not care about what mmc drivers do internally, aka
that fallback and the properties describe

SD UHS SDR50 speed is supported
and
SD UHS SDR104 speed is supported

So both are needed.

Thanks
Heiko

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