Arguments

From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout2.samsung.com ([203.254.224.25]:36596 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754068Ab2JBO3z (ORCPT ); Tue, 2 Oct 2012 10:29:55 -0400 From: Tomasz Stanislawski To: linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org Cc: airlied@redhat.com, m.szyprowski@samsung.com, t.stanislaws@samsung.com, kyungmin.park@samsung.com, laurent.pinchart@ideasonboard.com, sumit.semwal@ti.com, daeinki@gmail.com, daniel.vetter@ffwll.ch, robdclark@gmail.com, pawel@osciak.com, linaro-mm-sig@lists.linaro.org, hverkuil@xs4all.nl, remi@remlab.net, subashrp@gmail.com, mchehab@redhat.com, zhangfei.gao@gmail.com, s.nawrocki@samsung.com, k.debski@samsung.com, linux-doc@vger.kernel.org Subject: [PATCHv9 17/25] Documentation: media: description of DMABUF exporting in V4L2 Date: Tue, 02 Oct 2012 16:27:28 +0200 Message-id: <1349188056-4886-18-git-send-email-t.stanislaws@samsung.com> In-reply-to: <1349188056-4886-1-git-send-email-t.stanislaws@samsung.com> References: <1349188056-4886-1-git-send-email-t.stanislaws@samsung.com> Sender: linux-media-owner@vger.kernel.org List-ID: This patch adds description and usage examples for exporting DMABUF file descriptor in V4L2. Signed-off-by: Tomasz Stanislawski Signed-off-by: Kyungmin Park CC: linux-doc@vger.kernel.org --- Documentation/DocBook/media/v4l/compat.xml | 3 + Documentation/DocBook/media/v4l/io.xml | 3 + Documentation/DocBook/media/v4l/v4l2.xml | 1 + Documentation/DocBook/media/v4l/vidioc-expbuf.xml | 212 +++++++++++++++++++++ 4 files changed, 219 insertions(+) create mode 100644 Documentation/DocBook/media/v4l/vidioc-expbuf.xml diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml index a46f95b..f0512aa 100644 --- a/Documentation/DocBook/media/v4l/compat.xml +++ b/Documentation/DocBook/media/v4l/compat.xml @@ -2625,6 +2625,9 @@ ioctls. Importing DMABUF file descriptors as a new IO method described in . + + Exporting DMABUF files using &VIDIOC-EXPBUF; ioctl. + diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml index 5b58657..476f448 100644 --- a/Documentation/DocBook/media/v4l/io.xml +++ b/Documentation/DocBook/media/v4l/io.xml @@ -488,6 +488,9 @@ DMA buffer from userspace using a file descriptor previously exported for a different or the same device (known as the importer role), or both. This section describes the DMABUF importer role API in V4L2. + Refer to DMABUF exporting for +details about exporting a V4L2 buffers as DMABUF file descriptors. + Input and output devices support the streaming I/O method when the V4L2_CAP_STREAMING flag in the capabilities field of &v4l2-capability; returned by diff --git a/Documentation/DocBook/media/v4l/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml index eee6908..d8c2597 100644 --- a/Documentation/DocBook/media/v4l/v4l2.xml +++ b/Documentation/DocBook/media/v4l/v4l2.xml @@ -543,6 +543,7 @@ and discussions on the V4L mailing list. &sub-enuminput; &sub-enumoutput; &sub-enumstd; + &sub-expbuf; &sub-g-audio; &sub-g-audioout; &sub-g-crop; diff --git a/Documentation/DocBook/media/v4l/vidioc-expbuf.xml b/Documentation/DocBook/media/v4l/vidioc-expbuf.xml new file mode 100644 index 0000000..bf28e7d --- /dev/null +++ b/Documentation/DocBook/media/v4l/vidioc-expbuf.xml @@ -0,0 +1,212 @@ + + + + ioctl VIDIOC_EXPBUF + &manvol; + + + + VIDIOC_EXPBUF + Export a buffer as a DMABUF file descriptor. + + + + + + int ioctl + int fd + int request + struct v4l2_exportbuffer *argp + + + + + + Arguments + + + + fd + + &fd; + + + + request + + VIDIOC_EXPBUF + + + + argp + + + + + + + + + Description + + + Experimental + This is an experimental + interface and may change in the future. + + +This ioctl is an extension to the memory +mapping I/O method therefore it is available only for +V4L2_MEMORY_MMAP buffers. It can be used to export a +buffer as a DMABUF file at any time after buffers have been allocated with the +&VIDIOC-REQBUFS; ioctl. + + To export a buffer, applicationis fill &v4l2-exportbuffer;. The + type field is set to the same buffer type as was +previously used with &v4l2-requestbuffers; type . +Applications must also set the index field. Valid +index numbers range from zero to the number of buffers allocated with +&VIDIOC-REQBUFS; (&v4l2-requestbuffers; count ) +minus one. For multi plane API, applications set the plane + field to the index of the plane to be exported. Valid planes +range from zero to the maximal number of valid planes for currently active +format. For single plane API, applications must set plane + to zero. Additional flags may be posted in the +flags field. Refer to a manual for open() for details. +Currently only O_CLOEXEC is supported. All other fields must be set to zero. +In a case of multi-planar API, every plane is exported separately using +multiple VIDIOC_EXPBUF calls. + + After calling VIDIOC_EXPBUF the fd + field will be set by a driver. This is a DMABUF file +descriptor. The application may pass it to other API. Refer to DMABUF importing for details about importing DMABUF +files into V4L2 nodes. A developer is encouraged to close a DMABUF file when it +is no longer used to avoid a resource leak. + + + +

+ Examples + + + Exporting a buffer. + +int buffer_export(int v4lfd, &v4l2-buf-type; bt, int index, int *dmafd) +{ + &v4l2-exportbuffer; expbuf; + + memset(&expbuf, 0, sizeof expbuf); + expbuf.type = bt; + expbuf.index = index; + if (ioctl(v4lfd, &VIDIOC-EXPBUF;, &expbuf) == -1) { + perror("VIDIOC_EXPBUF"); + return -1; + } + + *dmafd = expbuf.fd; + + return 0; +} + + + + + Exporting a buffer using multi plane API. + +int buffer_export_mp(int v4lfd, &v4l2-buf-type; bt, int index, + int dmafd[], int n_planes) +{ + int i; + + for (i = 0; i < n_planes; ++i) { + &v4l2-exportbuffer; expbuf; + + memset(&expbuf, 0, sizeof expbuf); + expbuf.type = bt; + expbuf.index = index; + expbuf.plane = i; + if (ioctl(v4lfd, &VIDIOC-EXPBUF;, &expbuf) == -1) { + perror("VIDIOC_EXPBUF"); + while (i) + close(dmafd[--i]); + return -1; + } + dmafd[i] = expbuf.fd; + } + + return 0; +} + + +

+ + + + + struct <structname>v4l2_exportbuffer</structname> + + &cs-str; + + + __s32 + fd + The DMABUF file descriptor associated with a buffer. Set by + a driver. + + + __u32 + flags + Flags for newly created file, currently only +O_CLOEXEC is supported, refer to the manual of open() for more +details. + + + __u32 + type + Type of the buffer, same as &v4l2-format; +type or &v4l2-requestbuffers; +type, set by the application. See + + + __u32 + index + Number of the buffer, set by the application. This field is +only used for memory mapping I/O and can range from +zero to the number of buffers allocated with the &VIDIOC-REQBUFS; ioctl +(&v4l2-requestbuffers; count) minus one. + + + __u32 + plane + Index of the plane to be exported when using multi plane +API. Otherwise this value must be set to zero. + + + __u32 + reserved[11] + Reserved field for future use. Must be set to zero. + + + +

+ + + + + &return-value; + + + EINVAL + + A queue is not in MMAP mode or DMABUF exporting is not +supported or flags or type + or index or plane + fields are invalid. + + + + + + -- 1.7.9.5