drm/atmel-hlcdc: support bus-width (12/16/18/24) in endpoint nodes

This beats the heuristic that the connector is involved in what format
should be output for cases where this fails.

E.g. if there is a bridge that changes format between the encoder and the
connector, or if some of the RGB pins between the lcd controller and the
encoder are not routed on the PCB.

This is critical for the devices that have the "conflicting output
formats" issue (SAM9N12, SAM9X5, SAMA5D3), since the most significant
RGB bits move around depending on the selected output mode. For
devices that do not have the "conflicting output formats" issue
(SAMA5D2, SAMA5D4), this is completely irrelevant.

Acked-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180825085620.10566-5-peda@axentia.se

1 files changed, 69 insertions, 8 deletions

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
index c05c2b744981..f73d8a92274e 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
@@ -27,33 +27,94 @@
 
 #include "atmel_hlcdc_dc.h"
 
+struct atmel_hlcdc_rgb_output {
+	struct drm_encoder encoder;
+	int bus_fmt;
+};
+
 static const struct drm_encoder_funcs atmel_hlcdc_panel_encoder_funcs = {
 	.destroy = drm_encoder_cleanup,
 };
 
+static struct atmel_hlcdc_rgb_output *
+atmel_hlcdc_encoder_to_rgb_output(struct drm_encoder *encoder)
+{
+	return container_of(encoder, struct atmel_hlcdc_rgb_output, encoder);
+}
+
+int atmel_hlcdc_encoder_get_bus_fmt(struct drm_encoder *encoder)
+{
+	struct atmel_hlcdc_rgb_output *output;
+
+	output = atmel_hlcdc_encoder_to_rgb_output(encoder);
+
+	return output->bus_fmt;
+}
+
+static int atmel_hlcdc_of_bus_fmt(const struct device_node *ep)
+{
+	u32 bus_width;
+	int ret;
+
+	ret = of_property_read_u32(ep, "bus-width", &bus_width);
+	if (ret == -EINVAL)
+		return 0;
+	if (ret)
+		return ret;
+
+	switch (bus_width) {
+	case 12:
+		return MEDIA_BUS_FMT_RGB444_1X12;
+	case 16:
+		return MEDIA_BUS_FMT_RGB565_1X16;
+	case 18:
+		return MEDIA_BUS_FMT_RGB666_1X18;
+	case 24:
+		return MEDIA_BUS_FMT_RGB888_1X24;
+	default:
+		return -EINVAL;
+	}
+}
+
 static int atmel_hlcdc_attach_endpoint(struct drm_device *dev, int endpoint)
 {
-	struct drm_encoder *encoder;
+	struct atmel_hlcdc_rgb_output *output;
+	struct device_node *ep;
 	struct drm_panel *panel;
 	struct drm_bridge *bridge;
 	int ret;
 
+	ep = of_graph_get_endpoint_by_regs(dev->dev->of_node, 0, endpoint);
+	if (!ep)
+		return -ENODEV;
+
 	ret = drm_of_find_panel_or_bridge(dev->dev->of_node, 0, endpoint,
 					  &panel, &bridge);
-	if (ret)
+	if (ret) {
+		of_node_put(ep);
 		return ret;
+	}
 
-	encoder = devm_kzalloc(dev->dev, sizeof(*encoder), GFP_KERNEL);
-	if (!encoder)
+	output = devm_kzalloc(dev->dev, sizeof(*output), GFP_KERNEL);
+	if (!output) {
+		of_node_put(ep);
+		return -ENOMEM;
+	}
+
+	output->bus_fmt = atmel_hlcdc_of_bus_fmt(ep);
+	of_node_put(ep);
+	if (output->bus_fmt < 0) {
+		dev_err(dev->dev, "endpoint %d: invalid bus width\n", endpoint);
 		return -EINVAL;
+	}
 
-	ret = drm_encoder_init(dev, encoder,
+	ret = drm_encoder_init(dev, &output->encoder,
 			       &atmel_hlcdc_panel_encoder_funcs,
 			       DRM_MODE_ENCODER_NONE, NULL);
 	if (ret)
 		return ret;
 
-	encoder->possible_crtcs = 0x1;
+	output->encoder.possible_crtcs = 0x1;
 
 	if (panel) {
 		bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_Unknown);
@@ -62,7 +123,7 @@ static int atmel_hlcdc_attach_endpoint(struct drm_device *dev, int endpoint)
 	}
 
 	if (bridge) {
-		ret = drm_bridge_attach(encoder, bridge, NULL);
+		ret = drm_bridge_attach(&output->encoder, bridge, NULL);
 		if (!ret)
 			return 0;
 
@@ -70,7 +131,7 @@ static int atmel_hlcdc_attach_endpoint(struct drm_device *dev, int endpoint)
 			drm_panel_bridge_remove(bridge);
 	}
 
-	drm_encoder_cleanup(encoder);
+	drm_encoder_cleanup(&output->encoder);
 
 	return ret;
 }