Em Wed, 04 Nov 2015 11:07:09 -0200
Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx> escreveu:
> It is better to keep the documentation overview at the header file,
> as this makes easier for developers to remember to fix when needed.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
I forgot to add:
Suggested-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>
> ---
>
> As suggested during the KS Workshop, the best is to use the !P meta-tag , and keep
> the documentation overview at the header file.
>
> 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 “function is not available”.</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
> - “bottom half” 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>
> diff --git a/drivers/media/dvb-core/demux.h b/drivers/media/dvb-core/demux.h
> index ccc1f43cb9a9..f8014aabf37b 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 API
> + *
> + * 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 demux.h and located in
> + * drivers/media/dvb-core.
> + *
> + * 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.
> + *
> + * 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.
> + *
> + * 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 API 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 API 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 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 dmx_ts_cb() and dmx_section_cb()
> + * callbacks.
> */
>
> /**
--
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