diff options
Diffstat (limited to 'linux/Documentation')
| -rw-r--r--[-rwxr-xr-x] | linux/Documentation/dvb/get_dvb_firmware | 0 | ||||
| -rw-r--r--[-rwxr-xr-x] | linux/Documentation/video4linux/extract_xc3028.pl | 0 | ||||
| -rw-r--r-- | linux/Documentation/video4linux/v4l2-framework.txt | 48 |
3 files changed, 24 insertions, 24 deletions
diff --git a/linux/Documentation/dvb/get_dvb_firmware b/linux/Documentation/dvb/get_dvb_firmware index f2e908d7f..f2e908d7f 100755..100644 --- a/linux/Documentation/dvb/get_dvb_firmware +++ b/linux/Documentation/dvb/get_dvb_firmware diff --git a/linux/Documentation/video4linux/extract_xc3028.pl b/linux/Documentation/video4linux/extract_xc3028.pl index 2cb816047..2cb816047 100755..100644 --- a/linux/Documentation/video4linux/extract_xc3028.pl +++ b/linux/Documentation/video4linux/extract_xc3028.pl diff --git a/linux/Documentation/video4linux/v4l2-framework.txt b/linux/Documentation/video4linux/v4l2-framework.txt index a6005257a..48cdf8624 100644 --- a/linux/Documentation/video4linux/v4l2-framework.txt +++ b/linux/Documentation/video4linux/v4l2-framework.txt @@ -531,11 +531,11 @@ struct v4l2_device *v4l2_dev = vdev->v4l2_dev; video buffer helper functions ----------------------------- -The v4l2 core API provides a standard method for dealing with video -buffers. Those methods allow a driver to implement read(), mmap() and +The v4l2 core API provides a standard method for dealing with video +buffers. Those methods allow a driver to implement read(), mmap() and overlay() on a consistent way. -There are currently methods for using video buffers on devices that +There are currently methods for using video buffers on devices that supports DMA with scatter/gather method (videobuf-dma-sg), DMA with linear access (videobuf-dma-contig), and vmalloced buffers, mostly used on USB drivers (videobuf-vmalloc). @@ -544,50 +544,50 @@ Any driver using videobuf should provide operations (callbacks) for four handlers: ops->buf_setup - calculates the size of the video buffers and avoid they - to waste more than some maximum limit of RAM; + to waste more than some maximum limit of RAM; ops->buf_prepare - fills the video buffer structs and calls videobuf_iolock() to alloc and prepare mmaped memory; ops->buf_queue - advices the driver that another buffer were - requested (by read() or by QBUF); + requested (by read() or by QBUF); ops->buf_release - frees any buffer that were allocated. In order to use it, the driver need to have a code (generally called at interrupt context) that will properly handle the buffer request lists, announcing that a new buffer were filled. -The irq handling code should handle the videobuf task lists, in order -to advice videobuf that a new frame were filled, in order to honor to a +The irq handling code should handle the videobuf task lists, in order +to advice videobuf that a new frame were filled, in order to honor to a request. The code is generally like this one: - if (list_empty(&dma_q->active)) + if (list_empty(&dma_q->active)) return; - buf = list_entry(dma_q->active.next, struct vbuffer, vb.queue); + buf = list_entry(dma_q->active.next, struct vbuffer, vb.queue); - if (!waitqueue_active(&buf->vb.done)) + if (!waitqueue_active(&buf->vb.done)) return; /* Some logic to handle the buf may be needed here */ - list_del(&buf->vb.queue); - do_gettimeofday(&buf->vb.ts); - wake_up(&buf->vb.done); + list_del(&buf->vb.queue); + do_gettimeofday(&buf->vb.ts); + wake_up(&buf->vb.done); -Those are the videobuffer functions used on drivers, implemented on +Those are the videobuffer functions used on drivers, implemented on videobuf-core: - Videobuf init functions videobuf_queue_sg_init() - Initializes the videobuf infrastructure. This function should be - called before any other videobuf function on drivers that uses DMA + Initializes the videobuf infrastructure. This function should be + called before any other videobuf function on drivers that uses DMA Scatter/Gather buffers. videobuf_queue_dma_contig_init - Initializes the videobuf infrastructure. This function should be - called before any other videobuf function on drivers that need DMA + Initializes the videobuf infrastructure. This function should be + called before any other videobuf function on drivers that need DMA contiguous buffers. videobuf_queue_vmalloc_init() - Initializes the videobuf infrastructure. This function should be + Initializes the videobuf infrastructure. This function should be called before any other videobuf function on USB (and other drivers) that need a vmalloced type of videobuf. @@ -607,12 +607,12 @@ videobuf-core: Stops video handling, ends mmap and frees mmap and other buffers. - V4L2 api functions. Those functions correspond to VIDIOC_foo ioctls: - videobuf_reqbufs(), videobuf_querybuf(), videobuf_qbuf(), + videobuf_reqbufs(), videobuf_querybuf(), videobuf_qbuf(), videobuf_dqbuf(), videobuf_streamon(), videobuf_streamoff(). - V4L1 api function (corresponds to VIDIOCMBUF ioctl): videobuf_cgmbuf() - This function is used to provide backward compatibility with V4L1 + This function is used to provide backward compatibility with V4L1 API. - Some help functions for read()/poll() operations: @@ -623,7 +623,7 @@ videobuf-core: videobuf_poll_stream() polling help function -The better way to understand it is to take a look at vivi driver. One -of the main reasons for vivi is to be a videobuf usage example. the -vivi_thread_tick() does the task that the IRQ callback would do on PCI +The better way to understand it is to take a look at vivi driver. One +of the main reasons for vivi is to be a videobuf usage example. the +vivi_thread_tick() does the task that the IRQ callback would do on PCI drivers (or the irq callback on USB). |