[PATCH 2/3] arm64: dts: mediatek: mt8195-cherry: Fix ramp-delay for Vgpu

[Chen-Yu Tsai]

On Cherry, the MT6315 PMIC at USID 0x7 powering Vgpu has its slew rate
configured by firmware to 4500 uV/us, rather than the 6250 uV/us
currently specified in the device tree.

Since regulator-ramp-delay is specified in uV/us, specifying a higher
slew rate than what the PMIC actually uses results in an underestimated
voltage ramp time, risking GPU undervoltage when switching to higher
operating points.

Update regulator-ramp-delay on mt6315_7_vbuck1 to 4500 to match the
configured slew rate provided by MediaTek. (Vbcpu on USID 0x6 is
configured to 6250 uV/us and needs no change.)

Fixes: 260c04d425eb ("arm64: dts: mediatek: cherry: Enable MT6315 regulators on SPMI bus")
Cc: <stable at vger.kernel.org>
Signed-off-by: Chen-Yu Tsai <wenst at chromium.org>
---
Patch created with LLM. Values were translated from raw register values
by MediaTek.
---
 arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
index f23a0c7aa87e..81628d8a4b0e 100644
--- a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
@@ -1596,7 +1596,7 @@ mt6315_7_vbuck1: vbuck1 {
 				regulator-min-microvolt = <400000>;
 				regulator-max-microvolt = <1193750>;
 				regulator-enable-ramp-delay = <256>;
-				regulator-ramp-delay = <6250>;
+				regulator-ramp-delay = <4500>;
 				regulator-allowed-modes = <0 1 2>;
 			};
 		};
-- 
2.56.0.317.g454f8302e1-goog