Re: [PATCH v2 2/2] arm64: dts: s32g2: Disable support for SD/eMMC UHS mode

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On 30/08/2024 13:33, Ciprian Costea wrote:
From: Ciprian Marian Costea <ciprianmarian.costea@xxxxxxxxxxx>

Disable SD/eMMC UHS modes for NXP boards which do not set VCCQ voltage
supply to 1.8V by default, such as S32G274A-EVB and S32G274A-RDB2.

Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@xxxxxxxxxxx>

Reviewed-by: Matthias Brugger <mbrugger@xxxxxxxx>

---
  arch/arm64/boot/dts/freescale/s32g274a-evb.dts  | 1 +
  arch/arm64/boot/dts/freescale/s32g274a-rdb2.dts | 9 +++++++++
  2 files changed, 10 insertions(+)

diff --git a/arch/arm64/boot/dts/freescale/s32g274a-evb.dts b/arch/arm64/boot/dts/freescale/s32g274a-evb.dts
index 7ab917f547ef..b9a119eea2b7 100644
--- a/arch/arm64/boot/dts/freescale/s32g274a-evb.dts
+++ b/arch/arm64/boot/dts/freescale/s32g274a-evb.dts
@@ -39,5 +39,6 @@ &usdhc0 {
  	pinctrl-1 = <&pinctrl_usdhc0_100mhz>;
  	pinctrl-2 = <&pinctrl_usdhc0_200mhz>;
  	disable-wp;
+	no-1-8-v;
  	status = "okay";
  };
diff --git a/arch/arm64/boot/dts/freescale/s32g274a-rdb2.dts b/arch/arm64/boot/dts/freescale/s32g274a-rdb2.dts
index 8739f63771bc..aaa61a8ad0da 100644
--- a/arch/arm64/boot/dts/freescale/s32g274a-rdb2.dts
+++ b/arch/arm64/boot/dts/freescale/s32g274a-rdb2.dts
@@ -45,5 +45,14 @@ &usdhc0 {
  	pinctrl-1 = <&pinctrl_usdhc0_100mhz>;
  	pinctrl-2 = <&pinctrl_usdhc0_200mhz>;
  	disable-wp;
+	/* Remove no-1-8-v to enable higher speed modes for SD card.
+	 * However, this is not enough to enable HS400 or HS200 modes for eMMC.
+	 * In this case, the position of the resistor R797 must be changed
+	 * from A to B before removing the property.
+	 * If the property is removed without changing the resistor position,
+	 * HS*00 may be enabled, but the interface might be unstable because of
+	 * the wrong VCCQ voltage applied to the eMMC.
+	 */
+	no-1-8-v;
  	status = "okay";
  };




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