73 lines
2.6 KiB
Plaintext
73 lines
2.6 KiB
Plaintext
ION Memory Manager (ION)
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ION is a memory manager that allows for sharing of buffers between different
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processes and between user space and kernel space. ION manages different
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memory spaces by separating the memory spaces into "heaps". Depending on the
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type of heap ION must reserve memory using the msm specific memory reservation
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bindings (see Documentation/devicetree/bindings/arm/msm/memory-reserve.txt).
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Required properties for Ion
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- compatible: "qcom,msm-ion"
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All child nodes of a qcom,msm-ion node are interpreted as Ion heap
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configurations.
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Required properties for Ion heaps
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- reg: The ID of the ION heap.
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- qcom,ion-heap-type: The heap type to use for this heap. Should be one of
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the following:
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- "SYSTEM"
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- "SYSTEM_CONTIG"
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- "CARVEOUT"
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- "CHUNK"
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- "CP"
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- "DMA"
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- "SECURE_DMA"
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Optional properties for Ion heaps
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- compatible: "qcom,msm-ion-reserve" This is required if memory is to be reserved
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as specified by qcom,memory-reservation-size below.
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- qcom,heap-align: Alignment of start of the memory in the heap.
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- qcom,heap-adjacent: ID of heap this heap needs to be adjacent to.
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- qcom,memory-reservation-size: size of reserved memory for the ION heap.
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- qcom,memory-reservation-type: type of memory to be reserved
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(see memory-reserve.txt for information about memory reservations)
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- qcom,default-prefetch-size: Base value to be used for prefetching
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optimizations. Ignored if the heap does not support prefetching.
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Will set to a reasonable default value (e.g. the maximum heap size)
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if this option is not set.
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Example:
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qcom,ion {
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compatible = "qcom,msm-ion";
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#address-cells = <1>;
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#size-cells = <0>;
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qcom,ion-heap@25 {
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reg = <25>;
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qcom,ion-heap-type = "SYSTEM";
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};
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qcom,ion-heap@8 { /* CP_MM HEAP */
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compatible = "qcom,msm-ion-reserve";
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reg = <8>;
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qcom,heap-align = <0x1000>;
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linux,contiguous-region = <&secure_mem>;
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qcom,ion-heap-type = "SECURE_DMA";
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};
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qcom,ion-heap@29 { /* FIRMWARE HEAP */
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compatible = "qcom,msm-ion-reserve";
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reg = <29>;
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qcom,heap-align = <0x20000>;
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qcom,heap-adjacent = <8>;
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qcom,memory-reservation-type = "EBI1"; /* reserve EBI memory */
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qcom,memory-reservation-size = <0xA00000>;
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qcom,ion-heap-type = "CARVEOUT";
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};
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};
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