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author | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2020-03-04 10:50:14 +0100 |
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committer | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2020-04-14 10:32:45 +0200 |
commit | ff768f596fa19e719c88fbc9bd65e13145d944e7 (patch) | |
tree | 8574b980ade74110380566b7f07f84710db37fcd /Documentation/media/kapi/dtv-demux.rst | |
parent | media: docs: move uAPI book to userspace-api/media (diff) | |
download | linux-ff768f596fa19e719c88fbc9bd65e13145d944e7.tar.xz linux-ff768f596fa19e719c88fbc9bd65e13145d944e7.zip |
media: docs: kAPI docs: move them to driver-api
All those documents describe the media driver API. So, move
them to the right place within the Kernel documentation.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Diffstat (limited to 'Documentation/media/kapi/dtv-demux.rst')
-rw-r--r-- | Documentation/media/kapi/dtv-demux.rst | 84 |
1 files changed, 0 insertions, 84 deletions
diff --git a/Documentation/media/kapi/dtv-demux.rst b/Documentation/media/kapi/dtv-demux.rst deleted file mode 100644 index c0ae5dec5328..000000000000 --- a/Documentation/media/kapi/dtv-demux.rst +++ /dev/null @@ -1,84 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0 - -Digital TV Demux kABI ---------------------- - -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 -``include/media``. - -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 -:c:type:`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. - -Demux Callback API -~~~~~~~~~~~~~~~~~~ - -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 :c:func:`dmx_ts_cb()` and :c:func:`dmx_section_cb()` -callbacks. - -Digital TV Demux device registration functions and data structures -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -.. kernel-doc:: include/media/dmxdev.h - -High-level Digital TV demux interface -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -.. kernel-doc:: include/media/dvb_demux.h - -Driver-internal low-level hardware specific driver demux interface -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -.. kernel-doc:: include/media/demux.h |