linux-kernel - [PATCH 4/4] arm64: dts: renesas: rzv2-evk-cn15-sd: Add ramp delay for SD0 regulator

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Message-ID: <20260123225957.1007089-5-prabhakar.mahadev-lad.rj@bp.renesas.com>
Date: Fri, 23 Jan 2026 22:59:57 +0000
From: Prabhakar <prabhakar.csengg@...il.com>
To: Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	linux-renesas-soc@...r.kernel.org
Cc: devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Prabhakar <prabhakar.csengg@...il.com>,
	Biju Das <biju.das.jz@...renesas.com>,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: [PATCH 4/4] arm64: dts: renesas: rzv2-evk-cn15-sd: Add ramp delay for SD0 regulator

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

Set an appropriate ramp delay for the SD0 I/O voltage regulator in the
CN15 SD overlay to make UHS-I voltage switching reliable during card
initialization.

This issue was observed on the RZ/V2H EVK, while the same UHS-I cards
worked on the RZ/V2N EVK without problems. Adding the ramp delay makes
the behavior consistent and avoids SD init timeouts.

Before this change SD0 could fail with:
[    2.646242] mmc0: error -110 whilst initialising SD card

With the delay in place UHS-I cards enumerate correctly:
[    2.633493] mmc0: new UHS-I speed SDR104 SDXC card at address aaaa
[    2.641687] mmcblk0: mmc0:aaaa SR64G 59.5 GiB
[    2.651489]  mmcblk0: p1

Fixes: 3d6c2bc7629c8("arm64: dts: renesas: Add CN15 eMMC and SD overlays for RZ/V2H and RZ/V2N EVKs")
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
---
 arch/arm64/boot/dts/renesas/rzv2-evk-cn15-sd.dtso | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/renesas/rzv2-evk-cn15-sd.dtso b/arch/arm64/boot/dts/renesas/rzv2-evk-cn15-sd.dtso
index 0af1e0a6c7f4..fc53c1aae3b5 100644
--- a/arch/arm64/boot/dts/renesas/rzv2-evk-cn15-sd.dtso
+++ b/arch/arm64/boot/dts/renesas/rzv2-evk-cn15-sd.dtso
@@ -25,6 +25,7 @@ vqmmc_sdhi0: regulator-vqmmc-sdhi0 {
 		regulator-max-microvolt = <3300000>;
 		gpios-states = <0>;
 		states = <3300000 0>, <1800000 1>;
+		regulator-ramp-delay = <60>;
 	};
 };
 
-- 
2.52.0