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Documentation: uAPI: media: add V4L2_CID_FLASH_{DURATION,STROBE_OE}

Add the new strobe duration and hardware strobe output enable to v4l
uAPI documentation. Additionally add labels for cross-referencing v4l
controls.

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

authored by

Richard Leitner and committed by
Hans Verkuil fa0e06f2 5be4154f

+42
+42
Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst
··· 58 58 ``V4L2_CID_FLASH_CLASS (class)`` 59 59 The FLASH class descriptor. 60 60 61 + .. _v4l2-cid-flash-led-mode: 62 + 61 63 ``V4L2_CID_FLASH_LED_MODE (menu)`` 62 64 Defines the mode of the flash LED, the high-power white LED attached 63 65 to the flash controller. Setting this control may not be possible in ··· 83 81 84 82 85 83 84 + .. _v4l2-cid-flash-strobe-source: 85 + 86 86 ``V4L2_CID_FLASH_STROBE_SOURCE (menu)`` 87 87 Defines the source of the flash LED strobe. 88 88 ··· 101 97 - The flash strobe is triggered by an external source. Typically 102 98 this is a sensor, which makes it possible to synchronise the 103 99 flash strobe start to exposure start. 100 + This method of controlling flash LED strobe has two additional 101 + prerequisites: the strobe source's :ref:`strobe output 102 + <v4l2-cid-flash-strobe-oe>` must be enabled (if available) 103 + and the flash controller's :ref:`flash LED mode 104 + <v4l2-cid-flash-led-mode>` must be set to 105 + ``V4L2_FLASH_LED_MODE_FLASH``. 104 106 105 107 106 108 ··· 197 187 charged before strobing. LED flashes often require a cooldown period 198 188 after strobe during which another strobe will not be possible. This 199 189 is a read-only control. 190 + 191 + .. _v4l2-cid-flash-duration: 192 + 193 + ``V4L2_CID_FLASH_DURATION (integer)`` 194 + Duration of the flash strobe pulse generated by the strobe source, when 195 + using external strobe. This control shall be implemented by the device 196 + generating the hardware flash strobe signal, typically a camera sensor, 197 + connected to a flash controller. 198 + 199 + The flash controllers :ref:`strobe source <v4l2-cid-flash-strobe-source>` 200 + must be configured to ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL`` for this 201 + mode of operation. For more details please also take a look at the 202 + documentation there. 203 + 204 + The unit should be microseconds (µs) if possible. 205 + 206 + .. _v4l2-cid-flash-strobe-oe: 207 + 208 + ``V4L2_CID_FLASH_STROBE_OE (boolean)`` 209 + Enables the output of a hardware strobe signal from the strobe source, 210 + when using external strobe. This control shall be implemented by the device 211 + generating the hardware flash strobe signal, typically a camera sensor, 212 + connected to a flash controller. 213 + 214 + Provided the signal generating device driver supports it, the length of the 215 + strobe signal can be configured by adjusting its 216 + :ref:`flash duration <v4l2-cid-flash-duration>`. 217 + 218 + The flash controllers :ref:`strobe source <v4l2-cid-flash-strobe-source>` 219 + must be configured to ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL`` for this 220 + mode of operation. For more details please also take a look at the 221 + documentation there.