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1Ion Memory Manager
2
3Ion is a memory manager that allows for sharing of buffers via dma-buf.
4Ion allows for different types of allocation via an abstraction called
5a 'heap'. A heap represents a specific type of memory. Each heap has
6a different type. There can be multiple instances of the same heap
7type.
8
9Specific heap instances are tied to heap IDs. Heap IDs are not to be specified
10in the devicetree.
11
12Required properties for Ion
13
14- compatible: "linux,ion" PLUS a compatible property for the device
15
16All child nodes of a linux,ion node are interpreted as heaps
17
18required properties for heaps
19
20- compatible: compatible string for a heap type PLUS a compatible property
21for the specific instance of the heap. Current heap types
22-- linux,ion-heap-system
23-- linux,ion-heap-system-contig
24-- linux,ion-heap-carveout
25-- linux,ion-heap-chunk
26-- linux,ion-heap-dma
27-- linux,ion-heap-custom
28
29Optional properties
30- memory-region: A phandle to a memory region. Required for DMA heap type
31(see reserved-memory.txt for details on the reservation)
32
33Example:
34
35 ion {
36 compatbile = "hisilicon,ion", "linux,ion";
37
38 ion-system-heap {
39 compatbile = "hisilicon,system-heap", "linux,ion-heap-system"
40 };
41
42 ion-camera-region {
43 compatible = "hisilicon,camera-heap", "linux,ion-heap-dma"
44 memory-region = <&camera_region>;
45 };
46
47 ion-fb-region {
48 compatbile = "hisilicon,fb-heap", "linux,ion-heap-dma"
49 memory-region = <&fb_region>;
50 };
51 }