Helper class for dma-heap allocations. More...

Public Types
enum	DmaHeapFlag { DmaHeapFlag::Cma = 1 << 0, DmaHeapFlag::System = 1 << 1 }
	Type of the dma-heap. More...

using	DmaHeapFlags = Flags< DmaHeapFlag >
	A bitwise combination of DmaHeap::DmaHeapFlag values.

Public Member Functions
	DmaHeap (DmaHeapFlags flags=DmaHeapFlag::Cma)
	Construct a DmaHeap of a given type. More...

	~DmaHeap ()
	Destroy the DmaHeap instance.

bool	isValid () const
	Check if the DmaHeap instance is valid. More...

UniqueFD	alloc (const char *name, std::size_t size)
	Allocate a dma-buf from the DmaHeap. More...

Detailed Description

Helper class for dma-heap allocations.

DMA heaps are kernel devices that provide an API to allocate memory from different pools called "heaps", wrap each allocated piece of memory in a dmabuf object, and return the dmabuf file descriptor to userspace. Multiple heaps can be provided by the system, with different properties for the underlying memory.

This class wraps a DMA heap selected at construction time, and exposes functions to manage memory allocation.

Member Enumeration Documentation

◆ DmaHeapFlag

enum libcamera::DmaHeap::DmaHeapFlag

strong

Type of the dma-heap.

Enumerator
Cma	Allocate from a CMA dma-heap, providing physically-contiguous memory.
System	Allocate from the system dma-heap, using the page allocator.

Constructor & Destructor Documentation

◆ DmaHeap()

libcamera::DmaHeap::DmaHeap ( DmaHeapFlags type = DmaHeapFlag::Cma )

Construct a DmaHeap of a given type.

Parameters

[in] type The type(s) of the dma-heap(s) to allocate from

The DMA heap type is selected with the type parameter, which defaults to the CMA heap. If no heap of the given type can be accessed, the constructed DmaHeap instance is invalid as indicated by the isValid() function.

Multiple types can be selected by combining type flags, in which case the constructed DmaHeap will match one of the types. If the system provides multiple heaps that match the requested types, which heap is used is undefined.

Member Function Documentation

◆ alloc()

UniqueFD libcamera::DmaHeap::alloc	(	const char *	name,
		std::size_t	size
	)

Allocate a dma-buf from the DmaHeap.

Parameters

[in]	name	The name to set for the allocated buffer
[in]	size	The size of the buffer to allocate

Allocates a dma-buf with read/write access.

If the allocation fails, return an invalid UniqueFD.

Returns: The UniqueFD of the allocated buffer

◆ isValid()

libcamera::DmaHeap::isValid ( ) const

inline

Check if the DmaHeap instance is valid.

Returns: True if the DmaHeap is valid, false otherwise

The documentation for this class was generated from the following files:

include/libcamera/internal/dma_heaps.h
src/libcamera/dma_heaps.cpp

Public Types

Public Member Functions