<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>
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