Newer Tegra device-trees will specify a video output graph that involves
LVDS encoder bridge, This patch adds support for the LVDS encoder bridge
to the RGB output, allowing us to model display hardware properly.
Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
---
drivers/gpu/drm/tegra/drm.h | 2 ++
drivers/gpu/drm/tegra/output.c | 10 ++++++++++
drivers/gpu/drm/tegra/rgb.c | 34 ++++++++++++++++++++++++++++++++++
3 files changed, 46 insertions(+)
diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
index 804869799305..cccd368b6752 100644
--- a/drivers/gpu/drm/tegra/drm.h
+++ b/drivers/gpu/drm/tegra/drm.h
@@ -12,6 +12,7 @@
#include <linux/of_gpio.h>
#include <drm/drm_atomic.h>
+#include <drm/drm_bridge.h>
#include <drm/drm_edid.h>
#include <drm/drm_encoder.h>
#include <drm/drm_fb_helper.h>
@@ -116,6 +117,7 @@ struct tegra_output {
struct device_node *of_node;
struct device *dev;
+ struct drm_bridge *bridge;
struct drm_panel *panel;
struct i2c_adapter *ddc;
const struct edid *edid;
diff --git a/drivers/gpu/drm/tegra/output.c b/drivers/gpu/drm/tegra/output.c
index a6a711d54e88..37fc6b8c173f 100644
--- a/drivers/gpu/drm/tegra/output.c
+++ b/drivers/gpu/drm/tegra/output.c
@@ -180,6 +180,16 @@ int tegra_output_init(struct drm_device *drm, struct tegra_output *output)
int connector_type;
int err;
+ if (output->bridge) {
+ err = drm_bridge_attach(&output->encoder, output->bridge,
+ NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+ if (err) {
+ dev_err(output->dev, "cannot connect bridge: %d\n",
+ err);
+ return err;
+ }
+ }
+
if (output->panel) {
err = drm_panel_attach(output->panel, &output->connector);
if (err < 0)
diff --git a/drivers/gpu/drm/tegra/rgb.c b/drivers/gpu/drm/tegra/rgb.c
index 0562a7eb793f..0df213e92664 100644
--- a/drivers/gpu/drm/tegra/rgb.c
+++ b/drivers/gpu/drm/tegra/rgb.c
@@ -5,6 +5,7 @@
*/
#include <linux/clk.h>
+#include <linux/of_graph.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_panel.h>
@@ -210,6 +211,7 @@ static const struct drm_encoder_helper_funcs tegra_rgb_encoder_helper_funcs = {
int tegra_dc_rgb_probe(struct tegra_dc *dc)
{
+ const unsigned int encoder_port = 0, panel_port = 1;
struct device_node *np;
struct tegra_rgb *rgb;
int err;
@@ -226,6 +228,38 @@ int tegra_dc_rgb_probe(struct tegra_dc *dc)
rgb->output.of_node = np;
rgb->dc = dc;
+ /*
+ * Tegra devices that have LVDS panel utilize LVDS-encoder bridge
+ * for converting 24/18 RGB data-lanes into 8 lanes. Encoder usually
+ * have a powerdown control which needs to be enabled in order to
+ * transfer data to the panel. Historically devices that use an older
+ * device-tree version didn't model the bridge, assuming that encoder
+ * is turned ON by default, while today's DRM allows us to model LVDS
+ * encoder properly.
+ *
+ * Newer device-trees may utilize output->encoder->panel graph.
+ *
+ * For older device-trees we fall back to use nvidia,panel phandle.
+ */
+ np = of_graph_get_remote_node(rgb->output.of_node, encoder_port, -1);
+ if (np) {
+ rgb->output.bridge = of_drm_find_bridge(np);
+ of_node_put(np);
+
+ if (!rgb->output.bridge)
+ return -EPROBE_DEFER;
+
+ np = of_graph_get_remote_node(rgb->output.bridge->of_node,
+ panel_port, -1);
+ if (np) {
+ rgb->output.panel = of_drm_find_panel(np);
+ of_node_put(np);
+
+ if (IS_ERR(rgb->output.panel))
+ return PTR_ERR(rgb->output.panel);
+ }
+ }
+
err = tegra_output_probe(&rgb->output);
if (err < 0)
return err;
--
2.26.0
