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Message-ID: <20250821-drm-misc-next-v4-10-7060500f8fd3@foss.st.com>
Date: Thu, 21 Aug 2025 13:09:00 +0200
From: Raphael Gallais-Pou <raphael.gallais-pou@...s.st.com>
To: Yannick Fertre <yannick.fertre@...s.st.com>,
Philippe Cornu
<philippe.cornu@...s.st.com>,
Maarten Lankhorst
<maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>,
Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
Rob Herring <robh@...nel.org>,
"Krzysztof
Kozlowski" <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
"Maxime
Coquelin" <mcoquelin.stm32@...il.com>,
Alexandre Torgue
<alexandre.torgue@...s.st.com>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Christophe Roullier
<christophe.roullier@...s.st.com>
CC: <dri-devel@...ts.freedesktop.org>, <devicetree@...r.kernel.org>,
<linux-stm32@...md-mailman.stormreply.com>,
<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v4 10/13] 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 <raphael.gallais-pou@...s.st.com>
---
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 372a99d9cc5c3730e8fbeddeb6134a3b18d938b6..b44ff221e0da968be104ff8195f9bef79c90c57a 100644
--- a/arch/arm64/boot/dts/st/stm32mp251.dtsi
+++ b/arch/arm64/boot/dts/st/stm32mp251.dtsi
@@ -52,6 +52,12 @@ clk_rcbsec: clk-rcbsec {
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 f689b47c5010033120146cf1954d6624c0270045..48a95af1741c42300195b753b710e714abc60d96 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@...d0000 {
compatible = "st,stm32mp25-vdec";
--
2.25.1
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