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@oss.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

On 8/12/25 5:11 AM, Bjorn Andersson wrote:
> 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@oss.qualcomm.com>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad