[PATCH v3 08/13] arm64: dts: qcom: hamoa: Add Iris context bank subnodes

The VPU issues DMA through several SMMU streams, and the hardware does
not give every stream the same addressable range. The non-pixel stream
cannot address the low 600MB of IOVA space, while the pixel stream can
address the full range:
    +-----------------------------------------------------------+
    | non-pixel stream addressable range (600 MB - 3.5 GB)      |
    | 0x25800000 - 0xe0000000                                   |
    +-----------------------------------------------------------+
    | pixel stream addressable range (0 - 3.5 GB)               |
    | 0x00000000 - 0xe0000000                                   |
    +-----------------------------------------------------------+
A single "iommus" property on the video-codec node puts every stream in
one IOMMU domain sharing one IOVA allocator, so nothing restricts a
non-pixel buffer to avoid 0 to 600MB. Once an allocation lands below
that boundary the hardware faults, which shows up as unhandled SMMU page
faults and spontaneous reboots:
https://gitlab.freedesktop.org/drm/msm/-/work_items/100

Given that the address range restriction is for specific VPU stream, it
should be ideally be moved to that stream. To achieve the same, a subset
of streams is now represented as subnodes, so that each can be
associated with its respective addressable range. The design was discussed
and agreed by mainatiners here
https://lore.kernel.org/all/c7b956a9-d3e8-4e18-b780-5d08f5cd2ca1@kernel.org (local)

In the past, this limitation was addressed with an iommu-map approach,
with the iris driver dynamically creating the devices. That approach
was later concluded to be a hack to avoid having subnodes, and was NAKed
by the iommu maintainers. It was discussed in detail here:
https://lore.kernel.org/all/c7b956a9-d3e8-4e18-b780-5d08f5cd2ca1@kernel.org/ (local)

The video-codec node includes address-cells, size-cells and dma-ranges
to declare 1:1 mapping for DMA translation to the parent.

Tested-by: Daniel J Blueman <redacted>
Co-developed-by: Vishnu Reddy <redacted>
Signed-off-by: Vishnu Reddy <redacted>
Signed-off-by: Vikash Garodia <vikash.garodia@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/hamoa.dtsi | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/hamoa.dtsi b/arch/arm64/boot/dts/qcom/hamoa.dtsi
index 5e92645c5c3cd7f2491e8d76f51f583fdb34c98a..e1e0b7d91870f383bb5213033a34e1dc29595368 100644
--- a/arch/arm64/boot/dts/qcom/hamoa.dtsi
+++ b/arch/arm64/boot/dts/qcom/hamoa.dtsi

@@ -5463,10 +5463,12 @@ &config_noc SLAVE_VENUS_CFG QCOM_ICC_TAG_ACTIVE_ONLY>,
 			resets = <&gcc GCC_VIDEO_AXI0_CLK_ARES>;
 			reset-names = "bus";
 
-			iommus = <&apps_smmu 0x1940 0>,
-				 <&apps_smmu 0x1947 0>;
 			dma-coherent;
 
+			#address-cells = <1>;
+			#size-cells = <1>;
+			dma-ranges = <0x0 0x0 0x0 0xe0000000>;
+
 			/*
 			 * IRIS firmware is signed by vendors, only
 			 * enable on boards where the proper signed firmware

@@ -5474,6 +5476,15 @@ &config_noc SLAVE_VENUS_CFG QCOM_ICC_TAG_ACTIVE_ONLY>,
 			 */
 			status = "disabled";
 
+			non-pixel {
+				iommus = <&apps_smmu 0x1940 0x0>;
+				iommu-ranges = <0x25800000 0xba800000>;
+			};
+
+			pixel {
+				iommus = <&apps_smmu 0x1947 0x0>;
+			};
+
 			iris_opp_table: opp-table {
 				compatible = "operating-points-v2";
 

-- 
2.34.1