linux-kernel - [PATCH 0/2] arm64: dts: qcom: msm8916/39: Make blsp

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Message-Id: <20231204-msm8916-blsp-dma-remote-v1-0-3e49c8838c8d@gerhold.net>
Date:   Mon, 04 Dec 2023 11:21:19 +0100
From:   Stephan Gerhold <stephan@...hold.net>
To:     Bjorn Andersson <andersson@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Stephan Gerhold <stephan@...hold.net>, stable@...r.kernel.org
Subject: [PATCH 0/2] arm64: dts: qcom: msm8916/39: Make blsp_dma
 controlled-remotely

The blsp_dma controller is shared between the different subsystems, 
which is why it is already initialized by the firmware. We should not 
reinitialize it from Linux to avoid potential other users of the DMA 
engine to misbehave.

In mainline this can be described using the "qcom,controlled-remotely" 
property. In the downstream/vendor kernel from Qualcomm there is an 
opposite "qcom,managed-locally" property. This property is *not* set 
for the qcom,sps-dma@...4000 so adding "qcom,controlled-remotely" 
upstream matches the behavior of the downstream/vendor kernel.

Adding this seems to fix some weird issues with UART where both
input/output becomes garbled with certain obscure firmware versions on
some devices.

Signed-off-by: Stephan Gerhold <stephan@...hold.net>
---
Stephan Gerhold (2):
      arm64: dts: qcom: msm8916: Make blsp_dma controlled-remotely
      arm64: dts: qcom: msm8939: Make blsp_dma controlled-remotely

 arch/arm64/boot/dts/qcom/msm8916.dtsi | 1 +
 arch/arm64/boot/dts/qcom/msm8939.dtsi | 1 +
 2 files changed, 2 insertions(+)
---
base-commit: adcad44bd1c73a5264bff525e334e2f6fc01bb9b
change-id: 20231204-msm8916-blsp-dma-remote-516df8aac521

Best regards,
-- 
Stephan Gerhold <stephan@...hold.net>