On Tue, 22 Feb 2011, Hans Verkuil wrote:
> On Tuesday, February 22, 2011 17:39:25 Guennadi Liakhovetski wrote:
> > On Tue, 22 Feb 2011, Hans Verkuil wrote:
> >
> > > > Hi
> > > >
> > > > Any thoughts about the subj? Hasn't anyone run into a need to select
> > > > inputs on subdevices until now? Something like
> > > >
> > > > struct v4l2_subdev_video_ops {
> > > > ...
> > > > int (*enum_input)(struct v4l2_subdev *sd, struct v4l2_input
> > > > *inp);
> > > > int (*g_input)(struct v4l2_subdev *sd, unsigned int *i);
> > > > int (*s_input)(struct v4l2_subdev *sd, unsigned int i);
> > >
> > > That's done through s_routing. Subdevices know nothing about inputs as
> > > shown to userspace.
> > >
> > > If you want a test pattern, then the host driver needs to add a "Test
> > > Pattern" input and call s_routing with the correct values (specific to
> > > that subdev) to set it up.
> >
> > Hm, maybe I misunderstood something, but if we understand "host" in the
> > same way, then this doesn't seem very useful to me. What shall the host
> > have to do with various sensor inputs? It cannot know, whether the sensor
> > has a test-pattern "input" and if yes - how many of them. Many sensors
> > have several such patterns, and, I think, some of them also have some
> > parameters, like colour values, etc., which we don't have anything to map
> > to. But even without that - some sensors have several test patterns, which
> > they well might want to be able to switch between by presenting not just
> > one but several test inputs. So, shouldn't we have some enum_routing or
> > something for them?
>
> What you really want is to select a test pattern. A good solution would be
> to create a sensor menu control with all the test patterns it supports.
Ok, thinking a bit further about it. Let's take mt9p031 as an example - a
pretty simple bayer-only sensor. The driver is not yet in the mainline,
but I'll be pushing something simple in the mainline soon. I just picked
it up as an example, because it has quite a few test modes.
On the total it can generate 9 test patterns, including gradients, bars,
constant colour-field, etc. Apart from selecting a specific test pattern,
the RGB colour values and monochrome "intensity" values and bar widths can
be set for the colour-field and monochrome-bars test-patterns respectively.
Using a control menu we can select one of the 9 test-modes. But do we also
want standard controls for colour values and bar widths? Or are they too
hardware-specific and too unimportant and can only be supported by private
controls?
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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