Hi Sakari,
Thanks for your review, I have a few questions though, and the rest
will be addressed in the next version.
On Tue, Jan 29, 2019 at 02:39:49PM +0200, Sakari Ailus wrote:
> > +static int csi_notify_complete(struct v4l2_async_notifier *notifier)
> > +{
> > + struct sun4i_csi *csi = container_of(notifier, struct sun4i_csi,
> > + notifier);
> > + int ret;
> > +
> > + ret = v4l2_device_register_subdev_nodes(&csi->v4l);
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = sun4i_csi_v4l2_register(csi);
> > + if (ret < 0)
> > + return ret;
> > +
> > + return media_create_pad_link(&csi->src_subdev->entity, csi->src_pad,
> > + &csi->vdev.entity, 0,
> > + MEDIA_LNK_FL_ENABLED |
> > + MEDIA_LNK_FL_IMMUTABLE);
>
> This appears to create a link directly from the sensor entity to the video
> device entity. Is that intentional? I'd expect to see a CSI-2 receiver
> sub-device as well, which I don't see being created by the driver.
>
> This is indeed a novel proposal. I have some concerns though.
>
> The user doesn't have access to the configured media bus format (reflecting
> the format on the CSI-2 bus on receiver's side). It's thus difficult to
> figure out whether the V4L2 pixel format configured on the video node
> matches what the sensor outputs. Admittedly, we don't have a perfect
> solution to that whenever the DMA hardware supports multiple V4L2 pixel
> formats on a single media bus format. We might need to have a different
> solution for this one, should it be without that receiver sub-device.
>
> Could you add the CSI-2 receiver sub-device, please?
Even though the name of the controller is *very* confusing, this isn't
a MIPI-CSI receiver, but a parallel one that supports RGB and BT656
buses.
> > + csi->pad.flags = MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_MUST_CONNECT;
>
> Could you make it IMMUTABLE and ENABLED? If there is no need to disable it,
> that is.
The link is already created with those flags, and as far as I know it
doesn't exist for the pads
> > +static int csi_release(struct file *file)
> > +{
> > + struct sun4i_csi *csi = video_drvdata(file);
> > + int ret;
> > +
> > + mutex_lock(&csi->lock);
> > +
> > + ret = v4l2_fh_release(file);
>
> v4l2_fh_release() always returns 0. I guess it could be changed to return
> void. The reason it has int is that it could be used as the release
> callback as such.
>
> > + v4l2_pipeline_pm_use(&csi->vdev.entity, 0);
> > + pm_runtime_put(csi->dev);
> > +
> > + mutex_unlock(&csi->lock);
> > +
> > + return ret;
> > +}
Do you want me to change the construct then?
Thanks!
Maxime
--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
