[PATCH] arm64: dts: mediatek: mt8173: lower SD clock and disable wp on Elm

From: Icenowy Zheng
Date: Thu Jun 12 2025 - 10:42:15 EST


The microSD slot of Elm seems to have a little signal quality issue and
cannot work at 200MHz. In addition, a microSD slot cannot handle
write-protection.

Lower the clock frequency to 100MHz and add "disable-wp" property to
eliminate a note of assuming RW.

My Hana device, which is a Lenovo Flex 11 Chromebook, can handle 200MHz;
so hana DTSI still have its max SD frequency set to 200MHz.

Signed-off-by: Icenowy Zheng <uwu@xxxxxxxxxx>
---
arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi | 1 +
arch/arm64/boot/dts/mediatek/mt8173-elm.dts | 5 +++++
arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi | 1 -
3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi b/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi
index dfc5c2f0ddefd..3147240cfa6ae 100644
--- a/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi
@@ -68,6 +68,7 @@ trackpad2: trackpad@2c {
};

&mmc1 {
+ max-frequency = <200000000>;
wp-gpios = <&pio 42 GPIO_ACTIVE_HIGH>;
};

diff --git a/arch/arm64/boot/dts/mediatek/mt8173-elm.dts b/arch/arm64/boot/dts/mediatek/mt8173-elm.dts
index 2390d04204e83..3385183b60d36 100644
--- a/arch/arm64/boot/dts/mediatek/mt8173-elm.dts
+++ b/arch/arm64/boot/dts/mediatek/mt8173-elm.dts
@@ -13,3 +13,8 @@ / {
"google,elm-rev5", "google,elm-rev4", "google,elm-rev3",
"google,elm", "mediatek,mt8173";
};
+
+&mmc1 {
+ max-frequency = <100000000>;
+ disable-wp;
+};
diff --git a/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi b/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi
index 0d995b342d463..2a253a90bce1b 100644
--- a/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8173-elm.dtsi
@@ -402,7 +402,6 @@ &mmc1 {
pinctrl-0 = <&mmc1_pins_default>;
pinctrl-1 = <&mmc1_pins_uhs>;
bus-width = <4>;
- max-frequency = <200000000>;
cap-sd-highspeed;
sd-uhs-sdr50;
sd-uhs-sdr104;
--
2.49.0