[PATCH v14 1/7] libcamera: add DmaBufAllocator::exportBuffers()

[Cheng-Hao Yang]

Hi Kieran and Jacopo,

On Mon, Sep 30, 2024 at 2:33 PM Harvey Yang <chenghaoyang at chromium.org> wrote:
>
> Add a helper function exportBuffers in DmaBufAllocator to make it easier
> to use.
>
> It'll be used in Virtual Pipeline Handler and SoftwareIsp.
>
> Signed-off-by: Harvey Yang <chenghaoyang at chromium.org>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> Reviewed-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
> ---
>  .../libcamera/internal/dma_buf_allocator.h    | 13 +++++
>  src/libcamera/dma_buf_allocator.cpp           | 57 +++++++++++++++++++
>  2 files changed, 70 insertions(+)
>
> diff --git a/include/libcamera/internal/dma_buf_allocator.h b/include/libcamera/internal/dma_buf_allocator.h
> index d2a0a0d1..66d3b419 100644
> --- a/include/libcamera/internal/dma_buf_allocator.h
> +++ b/include/libcamera/internal/dma_buf_allocator.h
> @@ -7,11 +7,17 @@
>
>  #pragma once
>
> +#include <memory>
> +#include <string>
> +#include <vector>
> +
>  #include <libcamera/base/flags.h>
>  #include <libcamera/base/unique_fd.h>
>
>  namespace libcamera {
>
> +class FrameBuffer;
> +
>  class DmaBufAllocator
>  {
>  public:
> @@ -28,7 +34,14 @@ public:
>         bool isValid() const { return providerHandle_.isValid(); }
>         UniqueFD alloc(const char *name, std::size_t size);
>
> +       int exportBuffers(unsigned int count,
> +                         const std::vector<unsigned int> &frameSize,
> +                         std::vector<std::unique_ptr<FrameBuffer>> *buffers);
> +
>  private:
> +       std::unique_ptr<FrameBuffer> createBuffer(
> +               std::string name, const std::vector<unsigned int> &frameSizes);
> +
>         UniqueFD allocFromHeap(const char *name, std::size_t size);
>         UniqueFD allocFromUDmaBuf(const char *name, std::size_t size);
>         UniqueFD providerHandle_;
> diff --git a/src/libcamera/dma_buf_allocator.cpp b/src/libcamera/dma_buf_allocator.cpp
> index be6efb89..f8ed3de2 100644
> --- a/src/libcamera/dma_buf_allocator.cpp
> +++ b/src/libcamera/dma_buf_allocator.cpp
> @@ -22,6 +22,9 @@
>
>  #include <libcamera/base/log.h>
>  #include <libcamera/base/memfd.h>
> +#include <libcamera/base/shared_fd.h>
> +
> +#include <libcamera/framebuffer.h>
>
>  /**
>   * \file dma_buf_allocator.cpp
> @@ -205,4 +208,58 @@ UniqueFD DmaBufAllocator::alloc(const char *name, std::size_t size)
>                 return allocFromHeap(name, size);
>  }
>
> +/**
> + * \brief Allocate and export buffers from the DmaBufAllocator
> + * \param[in] count The number of requested FrameBuffers
> + * \param[in] frameSizes The sizes of planes in each FrameBuffer
> + * \param[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.
> + *
> + * \return The number of allocated buffers on success or a negative error code
> + * otherwise
> + */
> +int DmaBufAllocator::exportBuffers(unsigned int count,
> +                                  const std::vector<unsigned int> &frameSizes,
> +                                  std::vector<std::unique_ptr<FrameBuffer>> *buffers)
> +{
> +       for (unsigned int i = 0; i < count; ++i) {
> +               std::unique_ptr<FrameBuffer> buffer =
> +                       createBuffer("frame-" + std::to_string(i), frameSizes);
> +               if (!buffer) {
> +                       LOG(DmaBufAllocator, Error) << "Unable to create buffer";
> +
> +                       buffers->clear();
> +                       return -EINVAL;
> +               }
> +
> +               buffers->push_back(std::move(buffer));
> +       }
> +
> +       return count;
> +}
> +
> +std::unique_ptr<FrameBuffer>
> +DmaBufAllocator::createBuffer(std::string name,
> +                             const std::vector<unsigned int> &frameSizes)
> +{
> +       std::vector<FrameBuffer::Plane> planes;
> +
> +       unsigned int bufferSize = 0, offset = 0;
> +       for (auto frameSize : frameSizes)
> +               bufferSize += frameSize;

Maybe it's a bit late:
Do you think I should rename `frameSizes` as `planeSizes`,
and `bufferSize` as `frameSize`?

BR,
Harvey

> +
> +       SharedFD fd(alloc(name.c_str(), bufferSize));
> +       if (!fd.isValid())
> +               return nullptr;
> +
> +       for (auto frameSize : frameSizes) {
> +               planes.emplace_back(FrameBuffer::Plane{ fd, offset, frameSize });
> +               offset += frameSize;
> +       }
> +
> +       return std::make_unique<FrameBuffer>(planes);
> +}
> +
>  } /* namespace libcamera */
> --
> 2.46.1.824.gd892dcdcdd-goog
>