Re: [PATCH v6 03/11] Documentation: uAPI: media: add V4L2_CID_FLASH_DURATION

[Richard Leitner <richard.leitner@linux.dev>]

Hi Sakari,

On Mon, Aug 25, 2025 at 08:48:31AM +0300, Sakari Ailus wrote:
> On Mon, Aug 25, 2025 at 08:42:19AM +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 <richard.leitner@linux.dev>
> > > ---
> > >  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 <v4l2-cid-flash-led-mode>` is set
> >     to ``V4L2_FLASH_LED_MODE_FLASH`` and :ref:`strobe source
> >     <v4l2-cid-strobe-source>` is set to ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL``.
> >     The unit should be microseconds (µs) if possible.
> 
> Also adding a reference to V4L2_CID_FLASH_HW_STROBE_SIGNAL:
> 
> ``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
>     strobe source's :ref:`V4L2_CID_FLASH_HW_STROBE_SIGNAL
>     <v4l2-cid-flash-hw-strobe>` is enabled and flash LED driver's :ref:`flash
>     LED mode <v4l2-cid-flash-led-mode>` is set to ``V4L2_FLASH_LED_MODE_FLASH``
>     and :ref:`strobe source <v4l2-cid-strobe-source>` is set to
>     ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL``. The unit should be microseconds (µs)
>     if possible.
> 
> Similarly, the documentation for V4L2_CID_FLASH_HW_STROBE_SIGNAL should be
> amended with a reference, but the label needs to exist first. I think you
> could merge the two documentation patches to make this easier.

Thanks for the review. Extending the documentation as you suggested
defintely makes sense. Thank you also for your suggestion. That makes things
even easier.

I will send a v7 end of this week. If anything else pops up or causes
questions on this series please feel free to give feedback :)
I have my fingers crossed for v7 to be the last ;-)

Thanks again for your great feedback!

regards;rl

> 
> -- 
> Sakari Ailus