Searched full:buffer (Results 1 – 25 of 530) sorted by relevance
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| /Documentation/core-api/ |
| D | circular-buffers.rst | 16 buffer don't want to share a lock.
25 (*) What is a circular buffer?
35 What is a circular buffer?
38 First of all, what is a circular buffer? A circular buffer is a buffer of
42 buffer.
45 the buffer.
47 Typically when the tail pointer is equal to the head pointer, the buffer is
48 empty; and the buffer is full when the head pointer is one less than the tail
53 indices should be wrapped to 0 when they reach the end of the buffer, thus
54 allowing an infinite amount of data to flow through the buffer.
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| /Documentation/media/uapi/v4l/ |
| D | vidioc-qbuf.rst | 19 VIDIOC_QBUF - VIDIOC_DQBUF - Exchange a buffer with the driver
46 (capturing) or filled (output) buffer in the driver's incoming queue.
49 To enqueue a buffer applications set the ``type`` field of a struct
50 :c:type:`v4l2_buffer` to the same buffer type as was
59 When the buffer is intended for output (``type`` is
62 ``bytesused``, ``field`` and ``timestamp`` fields, see :ref:`buffer`
70 To enqueue a :ref:`memory mapped <mmap>` buffer applications set the
77 To enqueue a :ref:`user pointer <userp>` buffer applications set the
79 the address of the buffer and ``length`` to its size. When the
86 memory pages of the buffer in physical memory, they cannot be swapped
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| D | buffer.rst | 16 A buffer contains data exchanged by application and driver using one of
18 planes, while the buffer structure acts as a container for the planes.
33 ``V4L2_BUF_FLAG_TSTAMP_SRC_MASK`` in :ref:`buffer-flags`. These flags
40 flags are copied from the OUTPUT video buffer to the CAPTURE video
41 buffer.
47 V4L2 exposes parameters that influence the buffer size, or the way data is
48 laid out in the buffer. Those parameters are exposed through both formats and
50 that modifies the direction in which pixels are stored in the buffer, as well
51 as the buffer size when the selected format includes padding at the end of
54 The set of information needed to interpret the content of a buffer (e.g. the
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| D | mmap.rst | 34 unique buffer type value. The sets are independent and each set can hold
40 of buffers and buffer type, for example ``V4L2_BUF_TYPE_VIDEO_CAPTURE``.
54 multi-planar API, every plane of every buffer has to be mapped
56 be equal to number of buffers times number of planes in each buffer. The
92 printf("Not enough buffer memory\\n");
100 struct v4l2_buffer buffer;
102 memset(&buffer, 0, sizeof(buffer));
103 buffer.type = reqbuf.type;
104 buffer.memory = V4L2_MEMORY_MMAP;
105 buffer.index = i;
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| D | pixfmt-compressed.rst | 45 The decoder expects one Access Unit per buffer.
46 The encoder generates one Access Unit per buffer.
78 one output and one capture buffer must be provided for use
79 with this pixel format. The output buffer must contain the
81 corresponding frame to the matching capture buffer.
97 - MPEG1 Picture. Each buffer starts with a Picture header, followed
106 - MPEG2 Picture. Each buffer starts with a Picture header, followed
123 Exactly one output and one capture buffer must be provided for use with
124 this pixel format. The output buffer must contain the appropriate number
126 capture buffer.
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| /Documentation/filesystems/ |
| D | relay.txt | 13 buffer. User space applications mmap() or read() from the relay files
21 buffer data. The relay interface doesn't implement any form of data
32 Each relay channel has one buffer per CPU, each buffer has one or more
33 sub-buffers. Messages are written to the first sub-buffer until it is
37 sub-buffer, while the kernel continues writing to the next.
39 When notified that a sub-buffer is full, the kernel knows how many
41 message couldn't fit into a sub-buffer. Userspace can use this
44 After copying it, userspace can notify the kernel that a sub-buffer
98 such as buffer-full conditions would still need to be communicated via
108 access to relay channel buffer data. Here are the file operations
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| D | xfs-delayed-logging-design.txt | 14 than any other object (except maybe the superblock buffer) so keeping the
68 asynchronous. That is, they don't commit to disk until either a log buffer is
69 filled (a log buffer can hold multiple transactions) or a synchronous operation
94 transactions A through D are committed to disk in the same log buffer.
96 That is, a single log buffer may contain multiple copies of the same object,
99 necessary copy in the log buffer, and three stale copies that are simply
107 memory == log buffer), only it is doing it extremely inefficiently. It is using
110 formatting the changes in a transaction to the log buffer. Hence we cannot avoid
114 changes to objects in memory outside the log buffer infrastructure. Because of
172 trying to get the lock on object A to flush it to the log buffer. This appears
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| /Documentation/i2c/ |
| D | dma-considerations.rst | 11 Therefore, it is *not* mandatory that the buffer of an I2C message is DMA safe.
13 rarely used. However, it is recommended to use a DMA-safe buffer if your
24 For clients, if you use a DMA safe buffer in i2c_msg, set the I2C_M_DMA_SAFE
28 using an unsafe DMA buffer. To improve this situation, using I2C_M_DMA_SAFE in
43 the I2C core. One gives you a DMA-safe buffer for a given i2c_msg as long as a
48 If a buffer is returned, it is either msg->buf for the I2C_M_DMA_SAFE case or a
49 bounce buffer. But you don't need to care about that detail, just use the
50 returned buffer. If NULL is returned, the threshold was not met or a bounce
51 buffer could not be allocated. Fall back to PIO in that case.
53 In any case, a buffer obtained from above needs to be released. Another helper
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| /Documentation/driver-api/iio/ |
| D | triggered-buffers.rst | 7 IIO triggered buffer setup
10 * :c:func:`iio_triggered_buffer_setup` — Setup triggered buffer and pollfunc
13 * struct :c:type:`iio_buffer_setup_ops` — buffer setup related callbacks
15 A typical triggered buffer setup looks like this::
45 /* setup triggered buffer, usually in probe function */
52 * :c:type:`iio_buffer_setup_ops`, the buffer setup functions to be called at
53 predefined points in the buffer configuration sequence (e.g. before enable,
64 stores it in the internal buffer together with the timestamp recorded in the
69 .. kernel-doc:: drivers/iio/buffer/industrialio-triggered-buffer.c
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| D | buffers.rst | 5 * struct :c:type:`iio_buffer` — general buffer structure
8 * :c:func:`iio_buffer_get` — Grab a reference to the buffer
9 * :c:func:`iio_buffer_put` — Release the reference to the buffer
15 IIO buffer sysfs interface
17 An IIO buffer has an associated attributes directory under
18 :file:`/sys/bus/iio/iio:device{X}/buffer/*`. Here are some of the existing
22 stored by the buffer.
23 * :file:`enable`, activate buffer capture.
25 IIO buffer setup
28 The meta information associated with a channel reading placed in a buffer is
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| /Documentation/ABI/testing/ |
| D | dell-smbios-wmi | 9 IOCTL's and buffer formats are defined in:
14 buffer for your machine.
19 To determine the size of the buffer read() a u64 dword from
23 interface buffer, you can allocate a structure that represents
26 3) In the 'length' object store the size of the buffer you
29 4) In this buffer object, prepare as necessary for the SMBIOS
39 7) The output will be returned in the buffer object.
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| D | sysfs-bus-intel_th-devices-msc | 5 Description: (RW) Configure MSC buffer wrapping. 1 == wrapping enabled.
12 - "single", for contiguous buffer mode (high-order alloc);
16 - any of the currently loaded buffer sinks.
17 If operating mode changes, existing buffer is deallocated,
25 Description: (RW) Configure MSC buffer size for "single" or "multi" modes.
30 Writing to this file deallocates existing buffer (provided
38 Description: (RW) Trigger window switch for the MSC's buffer, in
40 triggering a window switch for the buffer. Returns an error in any
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| D | dev-kmsg | 6 to the kernel's printk buffer.
10 the kernel's printk buffer.
23 Accessing the buffer:
25 of the kernel's printk buffer.
28 first message in the buffer; there is no kernel-internal
36 Messages in the record ring buffer get overwritten as whole,
39 In case messages get overwritten in the circular buffer while
46 messages, in case the buffer gets overwritten. And they allow
47 to reconnect to the buffer and reconstruct the read position
52 seek to the first entry in the buffer
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| /Documentation/driver-api/ |
| D | dma-buf.rst | 1 Buffer Sharing and Synchronization
15 shared or exclusive fence(s) associated with the buffer.
21 buffer sharing API, how to use it for exporting and using shared buffers.
23 Any device driver which wishes to be a part of DMA buffer sharing, can do so as
27 exporter, and A as buffer-user/importer.
32 <dma_buf_ops>` for the buffer,
33 - allows other users to share the buffer by using dma_buf sharing APIs,
34 - manages the details of buffer allocation, wrapped int a :c:type:`struct
38 this buffer.
40 The buffer-user
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| D | frame-buffer.rst | 1 Frame Buffer Library
4 The frame buffer drivers depend heavily on four data structures. These
20 otherwise. A good example of this is the start of the frame buffer
21 memory. This "locks" the address of the frame buffer memory, so that it
31 Frame Buffer Memory
37 Frame Buffer Colormap
43 Frame Buffer Video Mode Database
52 Frame Buffer Macintosh Video Mode Database
58 Frame Buffer Fonts
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| D | sync_file.rst | 14 of attaching a fence to the buffer a producer driver (such as a GPU or V4L
15 driver) sends the fence related to the buffer to userspace via a sync_file.
18 will not use the buffer for anything before the fence(s) signals, i.e., the
19 driver that issued the fence is not using/processing the buffer anymore, so it
20 signals that the buffer is ready to use. And vice-versa for the consumer ->
23 Sync files allows userspace awareness on buffer sharing synchronization between
34 related to a buffer that the driver is processing or is going to process, so
36 dma_fence_signal(), when it has finished using (or processing) that buffer.
41 we need to wait for the fence(s) to signal before using any buffer related to
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| /Documentation/media/uapi/dvb/ |
| D | dmx-qbuf.rst | 19 DMX_QBUF - DMX_DQBUF - Exchange a buffer with the driver
48 (capturing) or filled (output) buffer in the driver's incoming queue.
51 To enqueue a buffer applications set the ``index`` field. Valid index
58 memory pages of the buffer in physical memory, so they cannot be swapped
63 (capturing) buffer from the driver's outgoing queue.
64 They just set the ``index`` field with the buffer ID to be queued.
68 By default ``DMX_DQBUF`` blocks when no buffer is in the outgoing
71 immediately with an ``EAGAIN`` error code when no buffer is available.
74 :ref:`buffer`.
86 buffer was in the outgoing queue.
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| D | dmx-querybuf.rst | 19 DMX_QUERYBUF - Query the status of a buffer
45 be used to query the status of a buffer at any time after buffers have
55 On success, the ``offset`` will contain the offset of the buffer from the
57 ``bytesused`` the number of bytes occupied by data in the buffer (payload).
63 buffer from the start of the device memory, the ``length`` field its size,
64 and the ``bytesused`` the number of bytes occupied by data in the buffer
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| /Documentation/media/kapi/ |
| D | v4l2-videobuf.rst | 26 including buffer allocation, queueing and dequeueing, and streaming
31 Buffer types
41 this kind of buffer normally requires hardware which can do
51 buffer can be unreliable on fragmented systems, but simpler DMA
57 [It's worth noting that there's a fourth kind of buffer: "overlay" buffers
62 as a form of scattered buffer, but there are very few implementations in
79 struct videobuf_queue instance for the management of the buffer queue,
110 Each buffer (in the form of a struct videobuf_buffer pointer) will be
111 passed to buf_prepare(), which should set the buffer's size, width, height,
112 and field fields properly. If the buffer's state field is
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| D | dtv-common.rst | 22 Digital TV Ring buffer
30 1) For performance reasons read and write routines don't check buffer sizes
39 count = dvb_ringbuffer_write(rbuf, buffer, buflen);
46 count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize));
53 Flushing the buffer counts as a read operation.
54 Resetting the buffer counts as a read and write operation.
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| /Documentation/networking/ |
| D | tls.rst | 76 send() data is directly encrypted from the userspace buffer provided
77 to the encrypted kernel send buffer if possible.
92 The kernel will need to allocate a buffer for the encrypted data.
93 This buffer is allocated at the time send() is called, such that
96 -ENOMEM and some data was left on the socket buffer from a previous
97 call using MSG_MORE, the MSG_MORE data is left on the socket buffer.
108 char buffer[16384];
109 recv(sock, buffer, 16384);
111 Received data is decrypted directly in to the user buffer if it is
113 buffer is too small, data is decrypted in the kernel and copied to
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| /Documentation/fb/ |
| D | framebuffer.rst | 2 The Frame Buffer Device
11 The frame buffer device provides an abstraction for the graphics hardware. It
12 represents the frame buffer of some video hardware and allows application
24 From the user's point of view, the frame buffer device looks just like any
26 specifies the frame buffer number.
31 0 = /dev/fb0 First frame buffer
32 1 = /dev/fb1 Second frame buffer
34 31 = /dev/fb31 32nd frame buffer
44 The frame buffer devices are also `normal` memory devices, this means, you can
49 There also can be more than one frame buffer at a time, e.g. if you have a
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| /Documentation/w1/masters/ |
| D | ds2490.rst | 33 a write buffer and a read buffer (along with sizes) as arguments.
34 The ds2490 block I/O command supports reset, write buffer, read
35 buffer, and strong pullup all in one command, instead of the current
37 write and read data. The write buffer needs to have the match rom
39 write buffer, both of which are known to the driver.
52 clear the entire bulk in buffer. It would be possible to read the
53 maximum buffer size to not run into this error condition, only extra
54 bytes in the buffer is a logic error in the driver. The code should
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| /Documentation/driver-api/early-userspace/ |
| D | buffer-format.rst | 2 initramfs buffer format
12 memory buffer protocol used by the initrd protocol, but the contents
13 is different. The initramfs buffer contains an archive which is
15 the initramfs buffer format.
17 The initramfs buffer format is based around the "newc" or "crc" CPIO
20 initramfs buffer is thus a single .cpio.gz file.
22 The full format of the initramfs buffer is defined by the following
42 In human terms, the initramfs buffer contains a collection of
95 tuple is looked up in a tuple buffer. If not found, it is entered in
96 the tuple buffer and the entry is created as usual; if found, a hard
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| /Documentation/virt/kvm/devices/ |
| D | s390_flic.txt | 23 Passes a buffer and length into the kernel which are then injected into
25 attr->addr contains the pointer to the buffer and attr->attr contains
26 the length of the buffer.
31 Copies all floating interrupts into a buffer provided by userspace.
32 When the buffer is too small it returns -ENOMEM, which is the indication
33 for userspace to try again with a bigger buffer.
34 -ENOBUFS is returned when the allocation of a kernelspace buffer has
39 attr->addr contains the userspace address of the buffer into which all
41 attr->attr contains the size of the buffer in bytes.
49 subsystem identification word passed via the buffer specified by
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