[libcamera-devel] [PATCH 03/11] Adds rkisp1 metadata required for the Android HAL to use it.

[Kieran Bingham]

Quoting Nicholas Roth (2022-10-26 05:40:11)
> +Kieran Bingham <kieran.bingham at ideasonboard.com> since Laurent is out.
> 
> > Could this be computed the same way we do it in the IPU3 IPA module ?
> 
> It looks like each of the computed IPU3 FrameDurationLimit values
> correspond to the minimum and maximum v4l2 blanking intervals. I suppose
> that makes sense, though I suspect the minimum frame duration will be
> constrained by i2c bandwidth and ISP limitations at the highest resolutions
> rather than the sensor blanking intervals based on the datasheet.
> 
> I'm not really sure what the best thing to do here is. I'm concerned that
> if we follow the IPU3 computation, we could easily end up asking for the
> ISP to push more pixels than it has throughput for. A very conservative
> approach might be to cap this at a few FPS, which is the advertised rate at
> the highest resolution, but I would not enjoy using the camera that way.
> Curious to read others' thoughts on this.
> 
> As a side-note, I'm really not sure why the IPU3 IPA treats
> FrameDurationLimits as a 3-tuple, when control_ids.yaml explicitly states:
>       description: |
>         The minimum and maximum (in that order) frame duration,
>         expressed in microseconds.
> ...
>       size: [2]

Uhhh - yes, the code over at IPAIPU3::updateControls() seems quite ...
odd. I'm not sure it's correct, it could be left over from some early
development. I'll add it to a task to take a look at.

> It looks like updateControls is only called once, during init(). We would
> need a hook that changes this static configuration for each video mode.

I believe it's supposed to be called after / during configure() too when
modes are updated. If it's missing, there's likely a bug there.



> On Tue, Oct 25, 2022 at 10:16 AM Nicholas Roth <nicholas at rothemail.net>
> wrote:
> 
> > > Careful, we're claiming full per-frame control capabilities with this
> > set to 0 :)
> >
> > Good catch— I’ll revert this line. I couldn’t easily find this in the ISP
> > manual and wanted to see what we’d need for FULL instead of LIMITED support
> > while I was debugging a camera2 crash.
> >
> > > On Oct 25, 2022, at 8:20 AM, Jacopo Mondi <jacopo at jmondi.org> wrote:
> > >
> > > Careful, we're claiming full per-frame control capabilities with this
> > > set to 0 :)
> >