linux-kernel - [PATCH 3/3] arm64: dts: qcom: sc7280: Add MDSS

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Message-Id: <20250811-sc7280-mdss-reset-v1-3-83ceff1d48de@oss.qualcomm.com>
Date: Mon, 11 Aug 2025 22:11:35 -0500
From: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
To: Bjorn Andersson <andersson@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        cros-qcom-dts-watchers@...omium.org,
        Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@....qualcomm.com>
Subject: [PATCH 3/3] arm64: dts: qcom: sc7280: Add MDSS_CORE reset to mdss

Like on other platforms, if the OS does not support recovering the state
left by the bootloader it needs access to MDSS_CORE, so that it can
clear the MDSS configuration.

Until now it seems no version of the bootloaders have done so, but e.g.
the Particle Tachyon ships with a bootloader that does leave the display
in a state that results in a series of iommu faults.

So let's provide the reset, to allow the OS to clear that state.

Signed-off-by: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
---
 arch/arm64/boot/dts/qcom/sc7280.dtsi | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sc7280.dtsi b/arch/arm64/boot/dts/qcom/sc7280.dtsi
index 64a2abd3010018e94eb50c534a509d6b4cf2473b..5eafcb84cd452ecc758922b69774837e9f5a899a 100644
--- a/arch/arm64/boot/dts/qcom/sc7280.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7280.dtsi
@@ -4724,6 +4724,8 @@ &mc_virt SLAVE_EBI1 QCOM_ICC_TAG_ALWAYS>,
 
 			iommus = <&apps_smmu 0x900 0x402>;
 
+			resets = <&dispcc DISP_CC_MDSS_CORE_BCR>;
+
 			#address-cells = <2>;
 			#size-cells = <2>;
 			ranges;

-- 
2.49.0