linux-kernel - [PATCH 2/3] arm64: dts: qcom: msm8939: Add missing MDSS reset

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250915-msm8916-resets-v1-2-a5c705df0c45@linaro.org>
Date: Mon, 15 Sep 2025 15:28:31 +0200
From: Stephan Gerhold <stephan.gerhold@...aro.org>
To: Bjorn Andersson <andersson@...nel.org>, 
 Konrad Dybcio <konradybcio@...nel.org>
Cc: Vincent Knecht <vincent.knecht@...loo.org>, 
 Bryan O'Donoghue <bryan.odonoghue@...aro.org>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] arm64: dts: qcom: msm8939: Add missing MDSS reset

On most MSM8939 devices, the bootloader already initializes the display to
show the boot splash screen. In this situation, MDSS is already configured
and left running when starting Linux. To avoid side effects from the
bootloader configuration, the MDSS reset can be specified in the device
tree to start again with a clean hardware state.

The reset for MDSS is currently missing in msm8939.dtsi, which causes
errors when the MDSS driver tries to re-initialize the registers:

 dsi_err_worker: status=6
 dsi_err_worker: status=6
 dsi_err_worker: status=6
 ...

It turns out that we have always indirectly worked around this by building
the MDSS driver as a module. Before v6.17, the power domain was temporarily
turned off until the module was loaded, long enough to clear the register
contents. In v6.17, power domains are not turned off during boot until
sync_state() happens, so this is no longer working. Even before v6.17 this
resulted in broken behavior, but notably only when the MDSS driver was
built-in instead of a module.

Cc: stable@...r.kernel.org
Fixes: 61550c6c156c ("arm64: dts: qcom: Add msm8939 SoC")
Signed-off-by: Stephan Gerhold <stephan.gerhold@...aro.org>
---
 arch/arm64/boot/dts/qcom/msm8939.dtsi | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/msm8939.dtsi b/arch/arm64/boot/dts/qcom/msm8939.dtsi
index 68b92fdb996c26e7a1aadedf0f52e1afca85c4ab..eb64ec35e7f0e1c63b0b96f68d30006c2e440998 100644
--- a/arch/arm64/boot/dts/qcom/msm8939.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8939.dtsi
@@ -1249,6 +1249,8 @@ mdss: display-subsystem@...0000 {

 			power-domains = <&gcc MDSS_GDSC>;

+			resets = <&gcc GCC_MDSS_BCR>;
+
 			#address-cells = <1>;
 			#size-cells = <1>;
 			#interrupt-cells = <1>;

-- 
2.50.1