[libcamera-devel] [PATCH v1] v4l2: V4L2CameraProxy: Add support for DMABUF buffer I/O in REQBUF ioctl

[Vedant Paranjape]

Hi Laurent,

On Tue, Nov 30, 2021 at 5:27 AM Laurent Pinchart
<laurent.pinchart at ideasonboard.com> wrote:
>
> Hi Vedant,
>
> On Tue, Nov 30, 2021 at 01:10:31AM +0530, Vedant Paranjape wrote:
> > To support importing DMABUF, we need to reqbufs with DMABUF mode.
> >
> > This patch enables using V4L2_MEMORY_DMABUF as one of the memory types
> > in vidioc_reqbuf to initialise DMA Buffer I/O
> >
> > Bug: https://bugs.libcamera.org/show_bug.cgi?id=89
> >
> > Signed-off-by: Vedant Paranjape <vedantparanjape160201 at gmail.com>
> > ---
> >  src/v4l2/v4l2_camera_proxy.cpp | 14 ++++++++++----
> >  1 file changed, 10 insertions(+), 4 deletions(-)
> >
> > diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
> > index f194e06345b7..c8861a531399 100644
> > --- a/src/v4l2/v4l2_camera_proxy.cpp
> > +++ b/src/v4l2/v4l2_camera_proxy.cpp
> > @@ -160,7 +160,8 @@ bool V4L2CameraProxy::validateBufferType(uint32_t type)
> >
> >  bool V4L2CameraProxy::validateMemoryType(uint32_t memory)
> >  {
> > -     return memory == V4L2_MEMORY_MMAP;
> > +     return (memory == V4L2_MEMORY_MMAP) ||
> > +                       (memory == V4L2_MEMORY_DMABUF);
>
> https://git.libcamera.org/libcamera/libcamera.git/tree/Documentation/coding-style.rst#n421

There's a bug in checkstyle, that's why I had to ignore it on this
one. Checkstyle was changing some irrelevant part of the code too.
So, I manually tried to fix this, but checkstyle still won't budge. I
have setup the script long back :)

>
> >  }
> >
> >  void V4L2CameraProxy::setFmtFromConfig(const StreamConfiguration &streamConfig)
> > @@ -468,7 +469,8 @@ int V4L2CameraProxy::vidioc_reqbufs(V4L2CameraFile *file, struct v4l2_requestbuf
> >       if (!hasOwnership(file) && owner_)
> >               return -EBUSY;
> >
> > -     arg->capabilities = V4L2_BUF_CAP_SUPPORTS_MMAP;
> > +     arg->capabilities = V4L2_BUF_CAP_SUPPORTS_MMAP |
> > +                                                V4L2_BUF_CAP_SUPPORTS_DMABUF;
> >       memset(arg->reserved, 0, sizeof(arg->reserved));
> >
> >       if (arg->count == 0) {
> > @@ -511,11 +513,15 @@ int V4L2CameraProxy::vidioc_reqbufs(V4L2CameraFile *file, struct v4l2_requestbuf
> >               struct v4l2_buffer buf = {};
> >               buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> >               buf.length = v4l2PixFormat_.sizeimage;
> > -             buf.memory = V4L2_MEMORY_MMAP;
> > -             buf.m.offset = i * v4l2PixFormat_.sizeimage;
> > +             buf.memory = arg->memory;
> >               buf.index = i;
> >               buf.flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> >
> > +             if (arg->memory == V4L2_MEMORY_MMAP)
> > +                     buf.m.offset = i * v4l2PixFormat_.sizeimage;
> > +             else if (arg->memory == V4L2_MEMORY_DMABUF)
> > +                     buf.m.fd = vcam_->getBufferFd(i).fd();
>
> This isn't right. Please test this patch with a V4L2 application that
> uses the device in DMABUF mode.

Okay, I'll do so.

>
> > +
> >               buffers_[i] = buf;
> >       }
> >
>
> --
> Regards,
>
> Laurent Pinchart

Regards,
Vedant Paranjape