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authorMauro Carvalho Chehab <mchehab@osg.samsung.com>2015-11-04 11:07:09 -0200
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>2015-11-16 07:39:11 -0200
commit7b6e55b9703810d771cf324d7b6cd0e1c095c86a (patch)
treecb34f469249e6381f72876aeebf9c1172f2971e5 /Documentation/DocBook/device-drivers.tmpl
parentd55ebd07b6c21a1c7e3e74f1b73b3b033cece2b5 (diff)
downloadlinux-7b6e55b9703810d771cf324d7b6cd0e1c095c86a.tar.bz2
[media] demux.h: move documentation overview from device-drivers.tmpl
It is better to keep the documentation overview at the header file, as this makes easier for developers to remember to fix when needed. Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Diffstat (limited to 'Documentation/DocBook/device-drivers.tmpl')
-rw-r--r--Documentation/DocBook/device-drivers.tmpl71
1 files changed, 6 insertions, 65 deletions
diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl
index 42a2d8593e39..c2bc8f779a9b 100644
--- a/Documentation/DocBook/device-drivers.tmpl
+++ b/Documentation/DocBook/device-drivers.tmpl
@@ -243,71 +243,12 @@ X!Isound/sound_firmware.c
!Idrivers/media/dvb-core/dvb_math.h
!Idrivers/media/dvb-core/dvb_ringbuffer.h
!Idrivers/media/dvb-core/dvbdev.h
- <sect1><title>Digital TV Demux API</title>
- <para>The kernel demux API 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 API is named
- <constant>demux.h</constant> and located in
- <constant>drivers/media/dvb-core</constant>.</para>
-
- <para>The demux API 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 API, it receives a pointer to the API of that
- resource.</para>
- <para>Each demux receives its TS input from a DVB front-end or from
- memory, as set via this demux API. In a system with more than one
- front-end, the API 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 API only controls front-ends regarding to their connections
- with demuxes; the APIs used to set the other front-end parameters,
- such as tuning, are not defined in this document.</para>
- <para>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 <constant>dmx_demux</constant>. For example,
- a demux interface might support Section filtering, but not PES
- filtering. The API client is expected to check the value of any
- function pointer before calling the function: the value of NULL means
- that the &#8220;function is not available&#8221;.</para>
- <para>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.</para>
- <para>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 API function
- is called from network device code, the function must not sleep.
- </para>
- </sect1>
-
- <section id="demux_callback_api">
- <title>Demux Callback API</title>
- <para>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.</para>
- <para>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.</para>
- <para>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
- &#8220;bottom half&#8221; mechanism or start a tasklet instead of
- making the callback function call directly from a hardware
- interrupt.</para>
- <para>This mechanism is implemented by
- <link linkend='API-dmx-ts-cb'>dmx_ts_cb()</link> and
- <link linkend='API-dmx-section-cb'>dmx_section_cb()</link>.</para>
- </section>
-
+ <sect1><title>Digital TV Demux API</title>
+!Pdrivers/media/dvb-core/demux.h Digital TV Demux API
+ </sect1>
+ <sect1><title>Demux Callback API</title>
+!Pdrivers/media/dvb-core/demux.h Demux Callback API
+ </sect1>
!Idrivers/media/dvb-core/demux.h
</sect1>
<sect1><title>Remote Controller devices</title>