Re: [PATCH] drm: rcar-du: Support panels connected directly to the DPAD outputs

Hi Laurent,

On Sat, Mar 02, 2019 at 06:17:25PM +0200, 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+renesas@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) {

You received a Tested-by, so I might surely be mistaken, but the caller of this function skips all remote nodes with a single port, doesn't it? https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/rcar-du/rcar_...

I don't have any DTS with a panel connected to the DPAD output so, as a test, I removed all endpoints except endpoint@0 from the 'hdmi0' device node, and the 'rcar_du_encoder_init()' function never gets called and DU probing fails with: rcar-du feb00000.display: no encoder found for endpoint /soc/display@feb00000/ports/port@1/endpoint, skipping

What am I missing?

Thanks j

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
  

• * panel bridge.
  

• */
  

• if ((output == RCAR_DU_OUTPUT_DPAD0 ||

•     output == RCAR_DU_OUTPUT_DPAD1) &&
  

•    rcar_du_encoder_count_ports(enc_node) == 1) {
  

Could this be cached?

• 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