linux-kernel - [PATCH 1/3] arm64: dts: imx8mm: Reduce GPU to nominal speed

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Date:   Tue, 28 Nov 2023 14:02:16 -0600
From:   Adam Ford <aford173@...il.com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     aford@...conembedded.com, Adam Ford <aford173@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Frieder Schrempf <frieder.schrempf@...tron.de>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] arm64: dts: imx8mm: Reduce GPU to nominal speed

When the GPU nodes were added, the GPU_PLL_OUT was configured
for 1000MHz, but this requires the SoC to run in overdrive mode
which requires an elevated voltage operating point.

Since this may run some boards out of spec, the default clock
should be set to 800MHz for nominal operating mode. Boards
that run at the higher voltage can update their clocks
accordingly.

Fixes: 4523be8e46be ("arm64: dts: imx8mm: Add GPU nodes for 2D and 3D core")
Signed-off-by: Adam Ford <aford173@...il.com>

diff --git a/arch/arm64/boot/dts/freescale/imx8mm.dtsi b/arch/arm64/boot/dts/freescale/imx8mm.dtsi
index 669fdd2c54e4..b33bc4855e5f 100644
--- a/arch/arm64/boot/dts/freescale/imx8mm.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8mm.dtsi
@@ -1402,7 +1402,7 @@ gpu_3d: gpu@...00000 {
 			assigned-clocks = <&clk IMX8MM_CLK_GPU3D_CORE>,
 					  <&clk IMX8MM_GPU_PLL_OUT>;
 			assigned-clock-parents = <&clk IMX8MM_GPU_PLL_OUT>;
-			assigned-clock-rates = <0>, <1000000000>;
+			assigned-clock-rates = <0>, <800000000>;
 			power-domains = <&pgc_gpu>;
 		};
 
@@ -1417,7 +1417,7 @@ gpu_2d: gpu@...08000 {
 			assigned-clocks = <&clk IMX8MM_CLK_GPU2D_CORE>,
 					  <&clk IMX8MM_GPU_PLL_OUT>;
 			assigned-clock-parents = <&clk IMX8MM_GPU_PLL_OUT>;
-			assigned-clock-rates = <0>, <1000000000>;
+			assigned-clock-rates = <0>, <800000000>;
 			power-domains = <&pgc_gpu>;
 		};
 
-- 
2.40.1