From 84b78bc2cb144ea0945320c5d1c4ad2085a704e6 Mon Sep 17 00:00:00 2001 From: Raphael Gallais-Pou Date: Fri, 22 Aug 2025 16:34:19 +0200 Subject: [PATCH] arm64: dts: st: add ltdc support on stm32mp255 Add the LTDC node for stm32mp255 SoC and handle its loopback clocks. ck_ker_ltdc has the CLK_SET_RATE_PARENT flag. While having this flag is semantically correct, it for now leads to an improper setting of the clock rate. The ck_ker_ltdc parent clock is the flexgen 27, which does not support changing rates yet. To overcome this issue, a fixed clock can be used for the kernel clock. Signed-off-by: Raphael Gallais-Pou Acked-by: Yannick Fertre Link: https://lore.kernel.org/r/20250822-drm-misc-next-v5-10-9c825e28f733@foss.st.com Signed-off-by: Alexandre Torgue --- arch/arm64/boot/dts/st/stm32mp251.dtsi | 6 ++++++ arch/arm64/boot/dts/st/stm32mp255.dtsi | 6 ++++++ 2 files changed, 12 insertions(+) diff --git a/arch/arm64/boot/dts/st/stm32mp251.dtsi b/arch/arm64/boot/dts/st/stm32mp251.dtsi index aecbdea07385f..e2a2fc9070f08 100644 --- a/arch/arm64/boot/dts/st/stm32mp251.dtsi +++ b/arch/arm64/boot/dts/st/stm32mp251.dtsi @@ -52,6 +52,12 @@ compatible = "fixed-clock"; clock-frequency = <64000000>; }; + + clk_flexgen_27_fixed: clk-54000000 { + #clock-cells = <0>; + compatible = "fixed-clock"; + clock-frequency = <54000000>; + }; }; firmware { diff --git a/arch/arm64/boot/dts/st/stm32mp255.dtsi b/arch/arm64/boot/dts/st/stm32mp255.dtsi index f689b47c50100..48a95af1741c4 100644 --- a/arch/arm64/boot/dts/st/stm32mp255.dtsi +++ b/arch/arm64/boot/dts/st/stm32mp255.dtsi @@ -5,6 +5,12 @@ */ #include "stm32mp253.dtsi" +<dc { + compatible = "st,stm32mp255-ltdc"; + clocks = <&clk_flexgen_27_fixed>, <&rcc CK_BUS_LTDC>, <&syscfg>, <&lvds>; + clock-names = "lcd", "bus", "ref", "lvds"; +}; + &rifsc { vdec: vdec@480d0000 { compatible = "st,stm32mp25-vdec"; -- 2.47.3