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

[Kieran Bingham]

Quoting Cheng-Hao Yang (2024-10-03 09:06:28)
> 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`?

plane sizes would probably be better, but I don't object either way.

I've just checked CI - and I see the unit tests are passing again, so
I'll see if I can find some time to re-test this later tonight if no one
else beats me to it.

This small rename could be handled when applying if this series is close
to merge.

> 
> 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
> >