Hi Sakari, On Tue, Apr 23, 2024 at 10:08:05AM +0000, Sakari Ailus wrote: > On Fri, Apr 19, 2024 at 08:17:20PM +0300, Laurent Pinchart wrote: > > On Tue, Apr 16, 2024 at 10:32:44PM +0300, Sakari Ailus wrote: > > > Document S_ROUTING behaviour for different devices. > > > > > > Generally in devices that produce streams the streams are static and some > > > can be enabled and disabled, whereas in devices that just transport them > > > or write them to memory, more configurability is allowed. Document this. > > > > > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> > > > Reviewed-by: Julien Massot <julien.massot@xxxxxxxxxxxxx> > > > --- > > > .../userspace-api/media/v4l/dev-subdev.rst | 24 +++++++++++++++++++ > > > 1 file changed, 24 insertions(+) > > > > > > diff --git a/Documentation/userspace-api/media/v4l/dev-subdev.rst b/Documentation/userspace-api/media/v4l/dev-subdev.rst > > > index d30dcb9e2537..de8dfd4f11a5 100644 > > > --- a/Documentation/userspace-api/media/v4l/dev-subdev.rst > > > +++ b/Documentation/userspace-api/media/v4l/dev-subdev.rst > > > @@ -593,6 +593,30 @@ Any configurations of a stream within a pad, such as format or selections, > > > are independent of similar configurations on other streams. This is > > > subject to change in the future. > > > > > > +Device types and routing setup > > > +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > > + > > > +Different kinds of sub-devices have differing behaviour for route activation, > > > +depending on the hardware. In all cases, however, only routes that have the > > > +``V4L2_SUBDEV_STREAM_FL_ACTIVE`` flag set are active. > > > + > > > +Devices generating the streams may allow enabling and disabling some of the > > > +routes or the configuration is fixed. If the routes can be disabled, not > > > > "... some of the routes, or have a fixed routing configuration." > > Seems fine. > > > > +declaring the routes (or declaring them without > > > +``VIDIOC_SUBDEV_STREAM_FL_ACTIVE`` flag set) in ``VIDIOC_SUBDEV_S_ROUTING`` will > > > +disable the routes while the sub-device driver retains the streams and their > > > +format and selection configuration. > > > > I still find the "retains their format and selection configuration" > > quite unclear :-S > > Alternatively we could say that the routes are simply not active, without > referring to explicitly to formats and selections. I.e.: > > If the routes can be disabled, not declaring the routes (or declaring them > without ``VIDIOC_SUBDEV_STREAM_FL_ACTIVE`` flag set) in > ``VIDIOC_SUBDEV_S_ROUTING`` will disable the routes. I'm fine with that. > > > The ``VIDIOC_SUBDEV_S_ROUTING`` will still > > > > s/will still/ioctl will still/ > > Both seem to exist, more common is without "ioctl": > > $ git grep '[`<]VIDIOC_SUBDEV' -- Documentation/userspace-api/media/|wc -l > 84 > $ git grep -i "VIDIOC_SUBDEV.*ioctl" -- Documentation/userspace-api/media/|wc -l > 34 You'll often find "ioctl" at the beginning of the next line :-) If you would like to avoid it, you should drop "The" at the beginning of the sentence. > > > +return such routes back to the user in the routes array, with the > > > +``V4L2_SUBDEV_STREAM_FL_ACTIVE`` flag unset. > > > + > > > +Devices transporting the streams almost always have more configurability with > > > +respect to routing. Typically any route between the sub-device's sink and source > > > +pads is possible, and multiple routes (usually up to certain limited number) may > > > +be active simultaneously. For such devices, no routes are created by the driver > > > +and user-created routes are fully replaced when ``VIDIOC_SUBDEV_S_ROUTING`` is > > > +called on the sub-device. Such newly created routes have the device's default > > > +configuration for format and selection rectangles. > > > + > > > Configuring streams > > > ^^^^^^^^^^^^^^^^^^^ > > > -- Regards, Laurent Pinchart
