Hi Philipp,
On Wednesday 21 August 2013 11:10:12 Philipp Zabel wrote:
> Am Mittwoch, den 21.08.2013, 03:02 +0200 schrieb Laurent Pinchart:
> > On Tuesday 13 August 2013 16:37:07 Philipp Zabel wrote:
> > > Hi Laurent,
> > >
> > > thanks for this update. I'm very happy about the move to the display
> > > entity model, given that the i.MX6 IPU has both drm/display and
> > > v4l2/capture ports> in a single device - this will allow to use a
> > > unified device tree binding scheme.
> >
> > Thanks for the support :-)
> >
> > > I'm still trying to see how this all fits together, so far I have only
> > > one comment, below.
> > >
> > > Am Freitag, den 09.08.2013, 19:14 +0200 schrieb Laurent Pinchart:
> > > [...]
> > >
> > > > +static int display_of_parse_dt(struct display_entity_notifier
> > > > *notifier,
> > > > + struct list_head *entities,
> > > > + struct device_node *node)
> > > > +{
> > > > + struct display_entity_of *entity;
> > > > + struct device_node *remote;
> > > > + struct device_node *ep = NULL;
> > > > + struct device_node *next;
> > > > + unsigned int num_entities = 0;
> > > > + int ret = 0;
> > > > +
> > > > + /* Walk the device tree and build a list of nodes. */
> > > > + dev_dbg(notifier->dev, "parsing node %s\n", node->full_name);
> > > > +
> > > > + while (1) {
> > > > + next = display_of_get_next_endpoint(node, ep);
> > > > + if (next == NULL)
> > > > + break;
> > > > +
> > > > + of_node_put(ep);
> > > > + ep = next;
> > > > +
> > > > + dev_dbg(notifier->dev, "handling endpoint %s\n", ep->full_name);
> > > > +
> > > > + remote = display_of_get_remote_port_parent(ep);
> > > > + if (remote == NULL)
> > > > + continue;
> > > > +
> > > > + /* Skip entities that we have already processed. */
> > > > + if (display_of_find_entity(entities, remote) || remote == node) {
> > > > + dev_dbg(notifier->dev,
> > > > + "entity %s already in list, skipping\n",
> > > > + remote->full_name);
> > > > + continue;
> > > > + }
> > >
> > > device tree nodes with status = "disabled" should be skipped here:
> > > if (!of_device_is_available(remote)) {
> > > dev_dbg(notifier->dev,
> > > "entity %s is disabled, skipping\n",
> > > remote->full_name);
> > > continue;
> > > }
> > >
> > > Otherwise the completion notification will never be delivered if there
> > > are any disabled entities in the graph.
> >
> > That's a good point, but if a device is disabled, why would it be in the
> > DT graph in the first place ? Do you have a use case for this ?
>
> This is mostly about separate encoders inside the SoC, which are always
> present but not useful unless the board designer connected something to
> the external pads. Those might be contained in the SoC .dtsi but have
> status = "disabled" set for board device tree writers' convenience.
> My use case would be the LVDS encoder bridge or the Synopsys Designware
> HDMI TX on i.MX6.
My point was that, if a DT node is disabled, it should not be linked in a CDF
graph in DT. However, I agree that it's easier to express the in-SoC links in
the .dtsi files, so you've got a point. I'll integrate the change in v4.
--
Regards,
Laurent Pinchart
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