From bb70589b67039e491dd60cf71272884e926a0f95 Mon Sep 17 00:00:00 2001 From: Lad Prabhakar Date: Fri, 23 Jan 2026 22:59:54 +0000 Subject: arm64: dts: renesas: rzt2h-n2h-evk: Add ramp delay for SD0 card regulator Add a ramp delay of 60 uV/us to the vqmmc_sdhi0 voltage regulator to fix UHS-I SD card detection failures. Measurements on CN78 pin 4 showed the actual voltage ramp time to be 21.86ms when switching between 3.3V and 1.8V. A 25ms ramp delay has been configured to provide adequate margin. The calculation is based on the voltage delta of 1.5V (3.3V - 1.8V): 1500000 uV / 60 uV/us = 25000 us (25ms) Prior to this patch, UHS-I cards failed to initialize with: mmc0: error -110 whilst initialising SD card After this patch, UHS-I cards are properly detected on SD0: mmc0: new UHS-I speed SDR104 SDXC card at address aaaa mmcblk0: mmc0:aaaa SR64G 59.5 GiB Fixes: d065453e5ee09 ("arm64: dts: renesas: rzt2h-rzn2h-evk: Enable SD card slot") Signed-off-by: Lad Prabhakar Reviewed-by: Geert Uytterhoeven Link: https://patch.msgid.link/20260123225957.1007089-2-prabhakar.mahadev-lad.rj@bp.renesas.com Signed-off-by: Geert Uytterhoeven --- arch/arm64/boot/dts/renesas/rzt2h-n2h-evk-common.dtsi | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm64/boot/dts/renesas/rzt2h-n2h-evk-common.dtsi b/arch/arm64/boot/dts/renesas/rzt2h-n2h-evk-common.dtsi index 510399febf29..f87c2492f414 100644 --- a/arch/arm64/boot/dts/renesas/rzt2h-n2h-evk-common.dtsi +++ b/arch/arm64/boot/dts/renesas/rzt2h-n2h-evk-common.dtsi @@ -53,6 +53,7 @@ regulator-max-microvolt = <3300000>; gpios-states = <0>; states = <3300000 0>, <1800000 1>; + regulator-ramp-delay = <60>; }; #endif -- cgit v1.2.3