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charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Hi Richard, On Mon, Sep 01, 2025 at 12:44:07PM +0200, Richard Leitner wrote: > On Mon, Aug 25, 2025 at 08:42:17AM +0300, Sakari Ailus wrote: > > Hi Richard, > > > > Thanks for the update (and for the ping!). > > > > On Wed, Jul 16, 2025 at 11:06:53AM +0200, Richard Leitner wrote: > > > Add the new strobe_duration control to v4l uAPI documentation. > > > > > > Signed-off-by: Richard Leitner > > > --- > > > Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst | 5 +++++ > > > 1 file changed, 5 insertions(+) > > > > > > diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst > > > index d22c5efb806a183a3ad67ec3e6550b002a51659a..03a58ef94be7c870f55d5a9bb09503995dbfb402 100644 > > > --- a/Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst > > > +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-flash.rst > > > @@ -186,3 +186,8 @@ Flash Control IDs > > > 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. > > > + > > > +``V4L2_CID_FLASH_DURATION (integer)`` > > > + Duration the flash should be on when the flash LED is in flash mode > > > + (V4L2_FLASH_LED_MODE_FLASH). The unit should be microseconds (µs) > > > + if possible. > > > > > > > I think we should add this is related to the hardware strobe. > > > > How about: > > > > ``V4L2_CID_FLASH_DURATION (integer)`` > > > > Duration of the flash strobe from the strobe source, typically a camera > > sensor. Controlling the flash LED strobe length this way requires that the > > flash LED driver's :ref:`flash LED mode ` is set > > to ``V4L2_FLASH_LED_MODE_FLASH`` and :ref:`strobe source > > ` is set to ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL``. > > The unit should be microseconds (µs) if possible. > > > > This requires of course the appropriate labels. > > > > I also wonder whether we should use 0,1 µs or even ns for the unit. > > Thanks for the pointer. > > I did a quick internet search and the shortest flash duration of > speedlights/studio strobes I found was Profoto D2 with 1/63000 sec ~> 15.9µs. > So I IMHO we are fine with 1µs resolution here. Works for me. -- Sakari Ailus