libcamera::ipa::V4L2Params< Traits > Class Template Reference

Helper class that represent an ISP configuration buffer. More...

Public Member Functions
	V4L2Params (Span< uint8_t > data, unsigned int version)
	Construct an instance of V4L2Params.
size_t	bytesused () const
	Retrieve the used size of the parameters buffer (in bytes)
template<typename Traits::id_type Id>
auto	block ()
	Retrieve the location of an ISP configuration block a return it.

Protected Member Functions
Span< uint8_t >	block (typename Traits::id_type type, unsigned int blockType, size_t blockSize)
	Populate an ISP configuration block a returns a reference to its memory.

Protected Attributes
Span< uint8_t >	data_
	The ISP parameters buffer memory.
size_t	used_
	The number of bytes used in the parameters buffer.
std::map< typename Traits::id_type, Span< uint8_t > >	blocks_
	Cache of ISP configuration blocks.

Detailed Description

template<typename Traits>
class libcamera::ipa::V4L2Params< Traits >

Helper class that represent an ISP configuration buffer.

This class represents an ISP configuration buffer. It is constructed with a reference to the memory mapped buffer that will be queued to the ISP driver.

This class is templated with the type of the enumeration of ISP blocks that each IPA module is expected to support. IPA modules are expected to derive this class by providing a 'param_traits' type that helps the class associate a block type with the actual memory area that represents the ISP configuration block.

// Define the supported ISP blocks
enum class myISPBlocks {
 Agc,
 Awb,
 ...
};
 
// Maps the C++ enum type to the kernel enum type and concrete parameter type
template<myISPBlocks B>
struct block_type {
};
 
template<>
struct block_type<myISPBlock::Agc> {
 using type = struct my_isp_kernel_config_type_agc;
 static constexpr kernel_enum_type blockType = MY_ISP_TYPE_AGC;
};
 
template<>
struct block_type<myISPBlock::Awb> {
 using type = struct my_isp_kernel_config_type_awb;
 static constexpr kernel_enum_type blockType = MY_ISP_TYPE_AWB;
};
 
 
// Convenience type to associate a block id to the 'block_type' overload
struct params_traits {
    using id_type = myISPBlocks;
    template<id_type Id> using id_to_details = block_type<Id>;
};
 
...
 
// Derive the V4L2Params class by providing params_traits
class MyISPParams : public V4L2Params<params_traits>
{
public:
    MyISPParams::MyISPParams(Span<uint8_t> data)
        : V4L2Params(data, kVersion)
    {
    }
};

Users of this class can then easily access an ISP configuration block as a V4L2ParamsBlock instance.

MyISPParams params(data);
 
auto awb = params.block<myISPBlocks::AWB>();
awb->gain00 = ...;
awb->gain01 = ...;
awb->gain10 = ...;
awb->gain11 = ...;

Constructor & Destructor Documentation

V4L2Params()

template<typename Traits >

libcamera::ipa::V4L2Params< Traits >::V4L2Params ( Span< uint8_t >  data, unsigned int  version  )

inline

Construct an instance of V4L2Params.

Parameters

[in]	data	Reference to the v4l2-buffer memory mapped area
[in]	version	The ISP parameters version the implementation supports

Member Function Documentation

block() [1/2]

template<typename Traits >

template<typename Traits::id_type Id>

libcamera::ipa::V4L2Params< Traits >::block ( )

inline

Retrieve the location of an ISP configuration block a return it.

Returns

A V4L2ParamsBlock instance that points to the ISP configuration block

block() [2/2]

template<typename Traits >

libcamera::ipa::V4L2Params< Traits >::block ( typename Traits::id_type  type, unsigned int  blockType, size_t  blockSize  )

inlineprotected

Populate an ISP configuration block a returns a reference to its memory.

Parameters

[in]	type	The ISP block identifier enumerated by the IPA module
[in]	blockType	The kernel-defined ISP block identifier, used to populate the block header
[in]	blockSize	The ISP block size, used to populate the block header

Initialize the block header with blockType and blockSize and returns a reference to the memory used to store an ISP configuration block.

IPA modules that derive the V4L2Params class shall use this function to retrieve the memory area that will be used to construct a V4L2ParamsBlock<T> before returning it to the caller.

bytesused()

template<typename Traits >

libcamera::ipa::V4L2Params< Traits >::bytesused ( ) const

inline

Retrieve the used size of the parameters buffer (in bytes)

The parameters buffer size is mostly used to populate the v4l2_buffer bytesused field before queueing the buffer to the ISP.

Returns

The number of bytes occupied by the ISP configuration parameters

---

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

• src/ipa/libipa/v4l2_params.h
• src/ipa/libipa/v4l2_params.cpp