[PATCH v3] arm64: dts: rockchip: enable SD UHS-I on Firefly-RK3399

[Yaozhong Li <yaozhonguwl@gmail.com>]

Contrary to its name, vcc_sdio is the IO supply of the SD card slot: the
schematics route it to SDMMC0_VDD. It is listed as the vmmc-supply
of the WiFi SDIO node instead, and that consumer keeps the rail from
switching to 1.8V.

The WiFi module's main VBAT input comes from vcc3v3_sys, and its IO
supply stays vcc1v8_s3. The card slot itself is fed from vcc3v3_sys
through a switch enabled by GPIO4_D6, which the vendor device tree calls
vcc_sd.

Fix the supplies of sdio0 and sdmmc accordingly, describe vcc_sd, and
enable SDR104, which now becomes possible.

With UHS enabled, sequential read from a 64GB SDXC card goes from
22 MB/s to 60 MB/s. WiFi remained associated at 5 GHz, with no WiFi
errors.

Assisted-by: LLM
Signed-off-by: Yaozhong Li <yaozhonguwl@gmail.com>
---
Changes in v3:
- Describe the slot's own supply, vcc_sd, and use it as the sdmmc
  vmmc-supply (Heiko). It is fed from vcc3v3_sys, and GPIO4_D6 controls
  the slot power switch: holding the pin low leaves the card unpowered.
  This is the same arrangement as vcc3v0_sd on the ROC-PC. The existing,
  unreferenced lcd_panel_reset pinctrl entry also names GPIO4_D6; the
  vendor tree uses the pin only for vcc_sd.
- Link to v2: https://lore.kernel.org/all/20261105102556.1365-1-yaozhonguwl@gmail.com/

Changes in v2:
- Point the sdio0 vmmc-supply at vcc3v3_sys, the WiFi module's VBAT input,
  instead of dropping it (Heiko)
- Rewrite the commit message (Heiko)
- Link to v1: https://lore.kernel.org/all/20260922055011.14972-1-yaozhonguwl@gmail.com/

On the boot-time issue described in v2: with the vmmc-supply in place
the sdmmc controller now probes after the GRF io-domain here, and a card
present at boot came up in SDR104 in 5 of 5 warm boots, against 0 of 8
before. That is a change in probe order rather than a fix for the
ordering problem itself.

 .../boot/dts/rockchip/rk3399-firefly.dts      | 24 ++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts b/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts
index 0568dfa..03858a4 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts
@@ -233,6 +233,19 @@ vcc5v0_typec: regulator-vcc5v0-typec {
 		vin-supply = <&vcc_sys>;
 	};
 
+	vcc_sd: regulator-vcc-sd {
+		compatible = "regulator-fixed";
+		enable-active-high;
+		gpio = <&gpio4 RK_PD6 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&vcc_sd_en>;
+		regulator-name = "vcc_sd";
+		regulator-boot-on;
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		vin-supply = <&vcc3v3_sys>;
+	};
+
 	vcc_sys: regulator-vcc-sys {
 		compatible = "regulator-fixed";
 		regulator-name = "vcc_sys";
@@ -731,6 +744,12 @@ wifi_enable_h: wifi-enable-h {
 		};
 	};
 
+	sdmmc {
+		vcc_sd_en: vcc-sd-en {
+			rockchip,pins = <4 RK_PD6 RK_FUNC_GPIO &pcfg_pull_none>;
+		};
+	};
+
 	usb-typec {
 		vcc5v0_typec_en: vcc5v0_typec_en {
 			rockchip,pins = <1 RK_PA3 RK_FUNC_GPIO &pcfg_pull_up>;
@@ -777,7 +796,7 @@ &sdio0 {
 
 	/* Power supply */
 	vqmmc-supply = <&vcc1v8_s3>;	/* IO line */
-	vmmc-supply = <&vcc_sdio>;	/* card's power */
+	vmmc-supply = <&vcc3v3_sys>;	/* card's power */
 
 	#address-cells = <1>;
 	#size-cells = <0>;
@@ -804,6 +823,9 @@ &sdmmc {
 	max-frequency = <150000000>;
 	pinctrl-names = "default";
 	pinctrl-0 = <&sdmmc_clk &sdmmc_cmd &sdmmc_bus4>;
+	sd-uhs-sdr104;
+	vmmc-supply = <&vcc_sd>;
+	vqmmc-supply = <&vcc_sdio>;
 	status = "okay";
 };
 

base-commit: 940de590b839f71d6dc846160534bf202401b8b7
-- 
2.55.0.windows.3