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Commit 7ba85fa4 authored by Sakari Ailus's avatar Sakari Ailus Committed by Mauro Carvalho Chehab
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[media] v4l: Add flash control documentation 

Add documentation for V4L2 flash controls.
Signed-off-by: default avatarSakari Ailus <sakari.ailus@iki.fi>
Acked-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 0b159acd
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Documentation/DocBook/media/v4l/compat.xml
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......@@ -2475,6 +2475,9 @@ ioctls.</para>
<listitem>
<para>&VIDIOC-DBG-G-CHIP-IDENT; ioctl.</para>
</listitem>
<listitem>
<para>Flash API. <xref linkend="flash-controls" /></para>
</listitem>
</itemizedlist>
</section>
......
Documentation/DocBook/media/v4l/controls.xml
View file @ 7ba85fa4
......@@ -2092,6 +2092,289 @@ manually or automatically if set to zero. Unit, range and step are driver-specif
<para>For more details about RDS specification, refer to
<xref linkend="en50067" /> document, from CENELEC.</para>
</section>
<section id="flash-controls">
<title>Flash Control Reference</title>
<note>
<title>Experimental</title>
<para>This is an <link linkend="experimental">experimental</link>
interface and may change in the future.</para>
</note>
<para>
The V4L2 flash controls are intended to provide generic access
to flash controller devices. Flash controller devices are
typically used in digital cameras.
</para>
<para>
The interface can support both LED and xenon flash devices. As
of writing this, there is no xenon flash driver using this
interface.
</para>
<section id="flash-controls-use-cases">
<title>Supported use cases</title>
<section>
<title>Unsynchronised LED flash (software strobe)</title>
<para>
Unsynchronised LED flash is controlled directly by the
host as the sensor. The flash must be enabled by the host
before the exposure of the image starts and disabled once
it ends. The host is fully responsible for the timing of
the flash.
</para>
<para>Example of such device: Nokia N900.</para>
</section>
<section>
<title>Synchronised LED flash (hardware strobe)</title>
<para>
The synchronised LED flash is pre-programmed by the host
(power and timeout) but controlled by the sensor through a
strobe signal from the sensor to the flash.
</para>
<para>
The sensor controls the flash duration and timing. This
information typically must be made available to the
sensor.
</para>
</section>
<section>
<title>LED flash as torch</title>
<para>
LED flash may be used as torch in conjunction with another
use case involving camera or individually.
</para>
</section>
</section>
<table pgwide="1" frame="none" id="flash-control-id">
<title>Flash Control IDs</title>
<tgroup cols="4">
<colspec colname="c1" colwidth="1*" />
<colspec colname="c2" colwidth="6*" />
<colspec colname="c3" colwidth="2*" />
<colspec colname="c4" colwidth="6*" />
<spanspec namest="c1" nameend="c2" spanname="id" />
<spanspec namest="c2" nameend="c4" spanname="descr" />
<thead>
<row>
<entry spanname="id" align="left">ID</entry>
<entry align="left">Type</entry>
</row><row rowsep="1"><entry spanname="descr" align="left">Description</entry>
</row>
</thead>
<tbody valign="top">
<row><entry></entry></row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_CLASS</constant></entry>
<entry>class</entry>
</row>
<row>
<entry spanname="descr">The FLASH class descriptor.</entry>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_LED_MODE</constant></entry>
<entry>menu</entry>
</row>
<row id="v4l2-flash-led-mode">
<entry spanname="descr">Defines the mode of the flash LED,
the high-power white LED attached to the flash controller.
Setting this control may not be possible in presence of
some faults. See V4L2_CID_FLASH_FAULT.</entry>
</row>
<row>
<entrytbl spanname="descr" cols="2">
<tbody valign="top">
<row>
<entry><constant>V4L2_FLASH_LED_MODE_NONE</constant></entry>
<entry>Off.</entry>
</row>
<row>
<entry><constant>V4L2_FLASH_LED_MODE_FLASH</constant></entry>
<entry>Flash mode.</entry>
</row>
<row>
<entry><constant>V4L2_FLASH_LED_MODE_TORCH</constant></entry>
<entry>Torch mode. See V4L2_CID_FLASH_TORCH_INTENSITY.</entry>
</row>
</tbody>
</entrytbl>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_STROBE_SOURCE</constant></entry>
<entry>menu</entry>
</row>
<row id="v4l2-flash-strobe-source"><entry
spanname="descr">Defines the source of the flash LED
strobe.</entry>
</row>
<row>
<entrytbl spanname="descr" cols="2">
<tbody valign="top">
<row>
<entry><constant>V4L2_FLASH_STROBE_SOURCE_SOFTWARE</constant></entry>
<entry>The flash strobe is triggered by using
the V4L2_CID_FLASH_STROBE control.</entry>
</row>
<row>
<entry><constant>V4L2_FLASH_STROBE_SOURCE_EXTERNAL</constant></entry>
<entry>The flash strobe is triggered by an
external source. Typically this is a sensor,
which makes it possible to synchronises the
flash strobe start to exposure start.</entry>
</row>
</tbody>
</entrytbl>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_STROBE</constant></entry>
<entry>button</entry>
</row>
<row>
<entry spanname="descr">Strobe flash. Valid when
V4L2_CID_FLASH_LED_MODE is set to
V4L2_FLASH_LED_MODE_FLASH and V4L2_CID_FLASH_STROBE_SOURCE
is set to V4L2_FLASH_STROBE_SOURCE_SOFTWARE. Setting this
control may not be possible in presence of some faults.
See V4L2_CID_FLASH_FAULT.</entry>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_STROBE_STOP</constant></entry>
<entry>button</entry>
</row>
<row><entry spanname="descr">Stop flash strobe immediately.</entry>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_STROBE_STATUS</constant></entry>
<entry>boolean</entry>
</row>
<row>
<entry spanname="descr">Strobe status: whether the flash
is strobing at the moment or not. This is a read-only
control.</entry>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_TIMEOUT</constant></entry>
<entry>integer</entry>
</row>
<row>
<entry spanname="descr">Hardware timeout for flash. The
flash strobe is stopped after this period of time has
passed from the start of the strobe.</entry>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_INTENSITY</constant></entry>
<entry>integer</entry>
</row>
<row>
<entry spanname="descr">Intensity of the flash strobe when
the flash LED is in flash mode
(V4L2_FLASH_LED_MODE_FLASH). The unit should be milliamps
(mA) if possible.</entry>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_TORCH_INTENSITY</constant></entry>
<entry>integer</entry>
</row>
<row>
<entry spanname="descr">Intensity of the flash LED in
torch mode (V4L2_FLASH_LED_MODE_TORCH). The unit should be
milliamps (mA) if possible. Setting this control may not
be possible in presence of some faults. See
V4L2_CID_FLASH_FAULT.</entry>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_INDICATOR_INTENSITY</constant></entry>
<entry>integer</entry>
</row>
<row>
<entry spanname="descr">Intensity of the indicator LED.
The indicator LED may be fully independent of the flash
LED. The unit should be microamps (uA) if possible.</entry>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_FAULT</constant></entry>
<entry>bitmask</entry>
</row>
<row>
<entry spanname="descr">Faults related to the flash. The
faults tell about specific problems in the flash chip
itself or the LEDs attached to it. Faults may prevent
further use of some of the flash controls. In particular,
V4L2_CID_FLASH_LED_MODE is set to V4L2_FLASH_LED_MODE_NONE
if the fault affects the flash LED. Exactly which faults
have such an effect is chip dependent. Reading the faults
resets the control and returns the chip to a usable state
if possible.</entry>
</row>
<row>
<entrytbl spanname="descr" cols="2">
<tbody valign="top">
<row>
<entry><constant>V4L2_FLASH_FAULT_OVER_VOLTAGE</constant></entry>
<entry>Flash controller voltage to the flash LED
has exceeded the limit specific to the flash
controller.</entry>
</row>
<row>
<entry><constant>V4L2_FLASH_FAULT_TIMEOUT</constant></entry>
<entry>The flash strobe was still on when
the timeout set by the user ---
V4L2_CID_FLASH_TIMEOUT control --- has expired.
Not all flash controllers may set this in all
such conditions.</entry>
</row>
<row>
<entry><constant>V4L2_FLASH_FAULT_OVER_TEMPERATURE</constant></entry>
<entry>The flash controller has overheated.</entry>
</row>
<row>
<entry><constant>V4L2_FLASH_FAULT_SHORT_CIRCUIT</constant></entry>
<entry>The short circuit protection of the flash
controller has been triggered.</entry>
</row>
</tbody>
</entrytbl>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_CHARGE</constant></entry>
<entry>boolean</entry>
</row>
<row><entry spanname="descr">Enable or disable charging of the xenon
flash capacitor.</entry>
</row>
<row>
<entry spanname="id"><constant>V4L2_CID_FLASH_READY</constant></entry>
<entry>boolean</entry>
</row>
<row>
<entry spanname="descr">Is the flash ready to strobe?
Xenon flashes require their capacitors charged before
strobing. LED flashes often require a cooldown period
after strobe during which another strobe will not be
possible. This is a read-only control.</entry>
</row>
<row><entry></entry></row>
</tbody>
</tgroup>
</table>
</section>
</section>
<!--
......
Documentation/DocBook/media/v4l/vidioc-g-ext-ctrls.xml
View file @ 7ba85fa4
......@@ -250,6 +250,13 @@ These controls are described in <xref
These controls are described in <xref
linkend="fm-tx-controls" />.</entry>
</row>
<row>
<entry><constant>V4L2_CTRL_CLASS_FLASH</constant></entry>
<entry>0x9c0000</entry>
<entry>The class containing flash device controls.
These controls are described in <xref
linkend="flash-controls" />.</entry>
</row>
</tbody>
</tgroup>
</table>
......
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