Hi Kieran,
On Wed, Mar 06, 2019 at 10:07:12AM +0000, Kieran Bingham wrote:
> On 02/03/2019 16:17, Laurent Pinchart wrote:
> > The R-Car DU driver assumes that a bridge is always connected to the DU
> > output. This is valid for the LVDS and HDMI outputs, but the DPAD
> > outputs can be connected directly to a panel, in which case no bridge is
> > available.
> >
> > To support this use case, detect whether the entities connected to the
> > DU DPAD outputs are encoders or panels based on the number of ports of
> > their DT node, and retrieve the corresponding type of DRM objects. For
> > panels, additionally create panel bridge instances.
> >
> > Signed-off-by: Laurent Pinchart <laurent.pinchart+rene...@ideasonboard.com>
>
> Except for some minor wording on the comment, which I'll let you handle,
>
> Reviewed-by: Kieran Bingham <kieran.bingham+rene...@ideasonboard.com>
>
> > ---
> > drivers/gpu/drm/rcar-du/rcar_du_encoder.c | 54 ++++++++++++++++++++---
> > 1 file changed, 48 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> > b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> > index 8ee4e762f4e5..595ecfa1ff0e 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> > +++ b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> > @@ -28,13 +28,33 @@ static const struct drm_encoder_funcs encoder_funcs = {
> > .destroy = drm_encoder_cleanup,
> > };
> >
> > +static unsigned int rcar_du_encoder_count_ports(struct device_node *node)
> > +{
> > + struct device_node *ports;
> > + struct device_node *port;
> > + unsigned int num_ports = 0;
> > +
> > + ports = of_get_child_by_name(node, "ports");
> > + if (!ports)
> > + ports = of_node_get(node);
> > +
> > + for_each_child_of_node(ports, port) {
> > + if (of_node_name_eq(port, "port"))
> > + num_ports++;
> > + }
> > +
> > + of_node_put(node);
> > +
> > + return num_ports;
> > +}
> > +
> > int rcar_du_encoder_init(struct rcar_du_device *rcdu,
> > enum rcar_du_output output,
> > struct device_node *enc_node)
> > {
> > struct rcar_du_encoder *renc;
> > struct drm_encoder *encoder;
> > - struct drm_bridge *bridge = NULL;
> > + struct drm_bridge *bridge;
> > int ret;
> >
> > renc = devm_kzalloc(rcdu->dev, sizeof(*renc), GFP_KERNEL);
> > @@ -48,11 +68,33 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
> > dev_dbg(rcdu->dev, "initializing encoder %pOF for output %u\n",
> > enc_node, output);
> >
> > - /* Locate the DRM bridge from the encoder DT node. */
> > - bridge = of_drm_find_bridge(enc_node);
> > - if (!bridge) {
> > - ret = -EPROBE_DEFER;
> > - goto done;
> > + /*
> > + * Locate the DRM bridge from the DT node. For the DPAD outputs, if the
> > + * DT node has a single port, consider it describes a panel and create a
>
>
> consider it as describing? (if it's an assumption that has been made)
>
> consider if it describes? (if it's conditional)
>
> I'm not sure I fully understand the intent of the sentence to correct it
> - but it needs a little tweak. The use of the word 'consider' makes me
> assume that it might not need a panel bridge, and some further decision
> needs to be made, but the code looks like it assumes one port means
> there should be a panel - and a bridge will be added.
Should I write it as "assume that it ..." ? I considered "consider" as
being less conditional than "assume", but I'll trust your judgement on
that.
> > + * panel bridge.
> > + */
> > + if ((output == RCAR_DU_OUTPUT_DPAD0 ||
> > + output == RCAR_DU_OUTPUT_DPAD1) &&
> > + rcar_du_encoder_count_ports(enc_node) == 1) {
> > + struct drm_panel *panel = of_drm_find_panel(enc_node);
> > +
> > + if (IS_ERR(panel)) {
> > + ret = PTR_ERR(panel);
> > + goto done;
> > + }
> > +
> > + bridge = devm_drm_panel_bridge_add(rcdu->dev, panel,
> > + DRM_MODE_CONNECTOR_DPI);
> > + if (IS_ERR(bridge)) {
> > + ret = PTR_ERR(bridge);
> > + goto done;
> > + }
> > + } else {
> > + bridge = of_drm_find_bridge(enc_node);
> > + if (!bridge) {
> > + ret = -EPROBE_DEFER;
> > + goto done;
> > + }
> > }
> >
> > ret = drm_encoder_init(rcdu->ddev, encoder, &encoder_funcs,
--
Regards,
Laurent Pinchart
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