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author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-01-11 22:17:44 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-01-11 22:17:44 -0800 |
commit | 47c62e4be78303ef52ffa8134026919d0890c5a9 (patch) | |
tree | c0ece2346076651da1f9fb33261d89f43b711be9 /drivers/media/dvb-core/demux.h | |
parent | Merge tag 'leds-for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds (diff) | |
parent | Merge branch 'patchwork' into v4l_for_linus (diff) | |
download | linux-dev-47c62e4be78303ef52ffa8134026919d0890c5a9.tar.xz linux-dev-47c62e4be78303ef52ffa8134026919d0890c5a9.zip |
Merge tag 'media/v4.5-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media
Pull media updates from Mauro Carvalho Chehab:
"The part of patches for Kernel 4.5. There's nothing really big here:
- driver-specific headers for media devices were moved to separate
directories, in order to make clear what headers belong to the core
kABI and require documentation
- Platform data for media drivers were moved from include/media to
include/linux/platform_data/media
- add a driver for cs3308 8-channel volume control, used on some
high-end capture boards
- lirc.h kAPI header were added at include/uapi/linux
- Driver cleanups, new board additions and improvements"
* tag 'media/v4.5-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (204 commits)
[media] rc: sunxi-cir: Initialize the spinlock properly
[media] rtl2832: do not filter out slave TS null packets
[media] rtl2832: print reg number on error case
[media] rtl28xxu: return demod reg page from driver cache
[media] coda: enable MPEG-2 ES decoding
[media] coda: don't start streaming without queued buffers
[media] coda: hook up vidioc_prepare_buf
[media] coda: relax coda_jpeg_check_buffer for trailing bytes
[media] coda: make to_coda_video_device static
[media] s5p-mfc: remove volatile attribute from MFC register addresses
[media] s5p-mfc: merge together s5p_mfc_hw_call and s5p_mfc_hw_call_void
[media] s5p-mfc: use spinlock to protect MFC context
[media] s5p-mfc: remove unnecessary callbacks
[media] s5p-mfc: make queue cleanup code common
[media] s5p-mfc: use one implementation of s5p_mfc_get_new_ctx
[media] s5p-mfc: constify s5p_mfc_codec_ops structures
[media] au8522: Avoid memory leak for device config data
[media] ir-lirc-codec.c: don't leak lirc->drv-rbuf
[media] uvcvideo: small cleanup in uvc_video_clock_update()
[media] uvcvideo: Fix reading the current exposure value of UVC
...
Diffstat (limited to 'drivers/media/dvb-core/demux.h')
-rw-r--r-- | drivers/media/dvb-core/demux.h | 67 |
1 files changed, 65 insertions, 2 deletions
diff --git a/drivers/media/dvb-core/demux.h b/drivers/media/dvb-core/demux.h index ccc1f43cb9a9..6d3b95b8939d 100644 --- a/drivers/media/dvb-core/demux.h +++ b/drivers/media/dvb-core/demux.h @@ -32,6 +32,49 @@ #include <linux/time.h> #include <linux/dvb/dmx.h> +/** + * DOC: Digital TV Demux + * + * The Kernel Digital TV Demux kABI defines a driver-internal interface for + * registering low-level, hardware specific driver to a hardware independent + * demux layer. It is only of interest for Digital TV device driver writers. + * The header file for this kABI is named demux.h and located in + * drivers/media/dvb-core. + * + * The demux kABI should be implemented for each demux in the system. It is + * used to select the TS source of a demux and to manage the demux resources. + * When the demux client allocates a resource via the demux kABI, it receives + * a pointer to the kABI of that resource. + * + * Each demux receives its TS input from a DVB front-end or from memory, as + * set via this demux kABI. In a system with more than one front-end, the kABI + * can be used to select one of the DVB front-ends as a TS source for a demux, + * unless this is fixed in the HW platform. + * + * The demux kABI only controls front-ends regarding to their connections with + * demuxes; the kABI used to set the other front-end parameters, such as + * tuning, are devined via the Digital TV Frontend kABI. + * + * The functions that implement the abstract interface demux should be defined + * static or module private and registered to the Demux core for external + * access. It is not necessary to implement every function in the struct + * &dmx_demux. For example, a demux interface might support Section filtering, + * but not PES filtering. The kABI client is expected to check the value of any + * function pointer before calling the function: the value of NULL means + * that the function is not available. + * + * Whenever the functions of the demux API modify shared data, the + * possibilities of lost update and race condition problems should be + * addressed, e.g. by protecting parts of code with mutexes. + * + * Note that functions called from a bottom half context must not sleep. + * Even a simple memory allocation without using %GFP_ATOMIC can result in a + * kernel thread being put to sleep if swapping is needed. For example, the + * Linux Kernel calls the functions of a network device interface from a + * bottom half context. Thus, if a demux kABI function is called from network + * device code, the function must not sleep. + */ + /* * Common definitions */ @@ -187,8 +230,28 @@ struct dmx_section_feed { int (*stop_filtering)(struct dmx_section_feed *feed); }; -/* - * Callback functions +/** + * DOC: Demux Callback + * + * This kernel-space API comprises the callback functions that deliver filtered + * data to the demux client. Unlike the other DVB kABIs, these functions are + * provided by the client and called from the demux code. + * + * The function pointers of this abstract interface are not packed into a + * structure as in the other demux APIs, because the callback functions are + * registered and used independent of each other. As an example, it is possible + * for the API client to provide several callback functions for receiving TS + * packets and no callbacks for PES packets or sections. + * + * The functions that implement the callback API need not be re-entrant: when + * a demux driver calls one of these functions, the driver is not allowed to + * call the function again before the original call returns. If a callback is + * triggered by a hardware interrupt, it is recommended to use the Linux + * bottom half mechanism or start a tasklet instead of making the callback + * function call directly from a hardware interrupt. + * + * This mechanism is implemented by dmx_ts_cb() and dmx_section_cb() + * callbacks. */ /** |