libcamera::DmaBufAllocator Class Reference

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

Public Types
enum	DmaBufAllocatorFlag { DmaBufAllocatorFlag::CmaHeap = 1 << 0, DmaBufAllocatorFlag::SystemHeap = 1 << 1, DmaBufAllocatorFlag::UDmaBuf = 1 << 2 }
	Type of the dma-buf provider. More...
using	DmaBufAllocatorFlags = Flags< DmaBufAllocatorFlag >
	A bitwise combination of DmaBufAllocator::DmaBufAllocatorFlag values.

Public Member Functions
	DmaBufAllocator (DmaBufAllocatorFlags flags=DmaBufAllocatorFlag::CmaHeap)
	Construct a DmaBufAllocator of a given type. More...
	~DmaBufAllocator ()
	Destroy the DmaBufAllocator instance.
bool	isValid () const
	Check if the DmaBufAllocator instance is valid. More...
UniqueFD	alloc (const char *name, std::size_t size)
	Allocate a dma-buf from the DmaBufAllocator. More...
int	exportBuffers (unsigned int count, const std::vector< unsigned int > &planeSizes, std::vector< std::unique_ptr< FrameBuffer >> *buffers)
	Allocate and export buffers from the DmaBufAllocator. More...

Detailed Description

Helper class for dma-buf allocations.

This class wraps a userspace dma-buf provider selected at construction time, and exposes functions to allocate dma-buffers from this provider.

Different providers may provide dma-buffers with different properties for the underlying memory. Which providers are acceptable is specified through the type argument passed to the DmaBufAllocator() constructor.

Member Enumeration Documentation

DmaBufAllocatorFlag

enum libcamera::DmaBufAllocator::DmaBufAllocatorFlag

strong

Type of the dma-buf provider.

Enumerator
CmaHeap	Allocate from a CMA dma-heap, providing physically-contiguous memory.
SystemHeap	Allocate from the system dma-heap, using the page allocator.
UDmaBuf	Allocate using a memfd + /dev/udmabuf.

Constructor & Destructor Documentation

DmaBufAllocator()

libcamera::DmaBufAllocator::DmaBufAllocator

(

DmaBufAllocatorFlags

type = DmaBufAllocatorFlag::CmaHeap

)

Construct a DmaBufAllocator of a given type.

Parameters

[in]

type

The type(s) of the dma-buf providers to allocate from

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

Multiple types can be selected by combining type flags, in which case the constructed DmaBufAllocator will match one of the types. If multiple requested types can work on the system, which provider is used is undefined.

Member Function Documentation

alloc()

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

Allocate a dma-buf from the DmaBufAllocator.

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

exportBuffers()

int libcamera::DmaBufAllocator::exportBuffers	(	unsigned int	count,
		const std::vector< unsigned int > &	planeSizes,
		std::vector< std::unique_ptr< FrameBuffer >> *	buffers
	)

Allocate and export buffers from the DmaBufAllocator.

Parameters

[in]	count	The number of requested FrameBuffers
[in]	planeSizes	The sizes of planes in each FrameBuffer
[out]	buffers	Array of buffers successfully allocated

Planes in a FrameBuffer are allocated with a single dma buf.

Todo:

Add the option to allocate each plane with a dma buf respectively.

Returns

The number of allocated buffers on success or a negative error code otherwise

isValid()

libcamera::DmaBufAllocator::isValid ( ) const

inline

Check if the DmaBufAllocator instance is valid.

Returns

True if the DmaBufAllocator is valid, false otherwise

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

• include/libcamera/internal/dma_buf_allocator.h
• src/libcamera/dma_buf_allocator.cpp