[PATCH 2/2] arm64: dts: qcom: hamoa: Reserve low IOVA range for Iris

[Daniel J Blueman <daniel@quora.org>]

On X1-family hamoa platforms, Iris DMA below IOVA 0x25800000 (600MB)
triggers unhandled SMMU page faults that cause spontaneous device
reboots. This is readily reproduced with web pages that drive
multiple concurrent video decode streams, eg ui.com.

Add a reserved-memory IOVA reservation node covering [0, 0x25800000)
and reference it from the Iris node so the IOMMU layer keeps DMA
allocations above that boundary.

This applies to all current hamoa.dtsi consumers (X1E80100/X1P42100/
X1P64100 boards); other Iris-bearing SoCs (sm8550/sm8650/sa8775p/
qcs8300) do not include hamoa.dtsi thus not affected.

Backports also require the preceding binding patch ("dt-bindings:
media: qcom,sm8550-iris: Allow IOVA reservation memory-region");
without it, dtbs_check rejects the second memory-region entry.

Link: https://github.com/qualcomm-linux/kernel-topics/issues/1157#issuecomment-4458933574
Cc: stable@vger.kernel.org
Signed-off-by: Daniel J Blueman <daniel@quora.org>
---
 arch/arm64/boot/dts/qcom/hamoa.dtsi | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/qcom/hamoa.dtsi b/arch/arm64/boot/dts/qcom/hamoa.dtsi
index 051dee076416..e2af0bc5e064 100644
--- a/arch/arm64/boot/dts/qcom/hamoa.dtsi
+++ b/arch/arm64/boot/dts/qcom/hamoa.dtsi
@@ -724,6 +724,15 @@ smem_mem: smem@ffe00000 {
 			hwlocks = <&tcsr_mutex 3>;
 			no-map;
 		};
+
+		/*
+		 * Iris DMA below IOVA 0x25800000 triggers unhandled SMMU
+		 * faults on hamoa platforms; reserve the range so the IOMMU
+		 * layer keeps allocations above this boundary.
+		 */
+		iris_iova: iris-iova {
+			iommu-addresses = <&iris 0x0 0x0 0x0 0x25800000>;
+		};
 	};

 	qup_opp_table_100mhz: opp-table-qup100mhz {
@@ -5479,7 +5488,7 @@ &config_noc SLAVE_VENUS_CFG QCOM_ICC_TAG_ACTIVE_ONLY>,
 			interconnect-names = "cpu-cfg",
 					     "video-mem";

-			memory-region = <&video_mem>;
+			memory-region = <&video_mem>, <&iris_iova>;

 			resets = <&gcc GCC_VIDEO_AXI0_CLK_ARES>;
 			reset-names = "bus";
--
2.53.0