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Support DRM bridges on NVIDIA Tegra

PATCH Superseded Dmitry Osipenko 4 participants 18 messages Apr 18, 2020 – May 24, 2020

Subsystems (5)

v5 of 10 Superseded Latest is v10 →

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#0 lore raw

v5 cover Support DRM bridges on NVIDIA Tegra

Hello,

This series adds initial support for the DRM bridges to NVIDIA Tegra DRM driver. This is required by newer device-trees where we model the LVDS encoder bridge properly.

Changelog:

v5: - Added new patches that make drm_of_find_panel_or_bridge() more usable
if graph isn't defined in a device-tree:

of_graph: add of_graph_get_local_port()
drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence

- Updated "Support DRM bridges" patch to use drm_of_find_panel_or_bridge() directly and added WARN_ON(output->panel || output->bridge) sanity-check.

- Added new "Wrap directly-connected panel into DRM bridge" patch, as was suggested by Laurent Pinchart.

v4: - Following review comments that were made by Laurent Pinchart to the v3,
we now create and use the "bridge connector".

v3: - Following recommendation from Sam Ravnborg, the new bridge attachment
model is now being used, i.e. we ask bridge to *not* create a connector using the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag.

- The bridge is now created only for the RGB (LVDS) output, and only when necessary. For now we don't need bridges for HDMI or DSI outputs.

- I noticed that we're leaking OF node in the panel's error code path, this is fixed now by the new patch "Don't leak OF node on error".

v2: - Added the new "rgb: Don't register connector if bridge is used"
patch, which hides the unused connector provided by the Tegra DRM driver when bridge is used, since bridge provides its own connector to us.

- Please notice that the first "Support DRM bridges" patch was previously sent out as a standalone v1 change.

Dmitry Osipenko (6):
of_graph: add of_graph_get_local_port()
drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence drm/tegra: output: Don't leak OF node on error
drm/tegra: output: Support DRM bridges
drm/tegra: output: rgb: Support LVDS encoder bridge drm/tegra: output: rgb: Wrap directly-connected panel into DRM bridge

 drivers/gpu/drm/drm_of.c       | 13 +++++-
 drivers/gpu/drm/tegra/drm.h    |  2 +
 drivers/gpu/drm/tegra/output.c | 21 +++++++--
 drivers/gpu/drm/tegra/rgb.c    | 85 +++++++++++++++++++++-------------
 drivers/of/property.c          | 32 +++++++++----
 include/linux/of_graph.h       |  7 +++
 6 files changed, 114 insertions(+), 46 deletions(-)
Signature · 1 line
2.26.0
#1 lore raw

PATCH v5 1/6 of_graph: add of_graph_get_local_port()

In some case, like a DRM display code for example, it's useful to silently check whether port node exists at all in a device-tree before proceeding with parsing the graph.

This patch adds of_graph_get_local_port() which returns pointer to a local port node, or NULL if graph isn't specified in a device-tree for a given device node.

---
 drivers/of/property.c    | 32 +++++++++++++++++++++++---------
 include/linux/of_graph.h |  7 +++++++
 2 files changed, 30 insertions(+), 9 deletions(-)
drivers/of/property.c +23 -9
index 252e4f600155..5dbeccaabb86 100644
@@ -608,15 +608,7 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
 	 * parent port node.
 	 */
 	if (!prev) {
-		struct device_node *node;
-
-		node = of_get_child_by_name(parent, "ports");
-		if (node)
-			parent = node;
-
-		port = of_get_child_by_name(parent, "port");
-		of_node_put(node);
-
+		port = of_graph_get_local_port(parent);
 		if (!port) {
 			pr_err("graph: no port node found in %pOF\n", parent);
 			return NULL;
@@ -765,6 +757,28 @@ struct device_node *of_graph_get_remote_port(const struct device_node *node)
 }
 EXPORT_SYMBOL(of_graph_get_remote_port);
 
+/**
+ * of_graph_get_local_port() - get local port node
+ * @node: pointer to a local endpoint device_node
+ *
+ * Return: First local port node associated with local endpoint node linked
+ *	   to @node. Use of_node_put() on it when done.
+ */
+struct device_node *of_graph_get_local_port(const struct device_node *node)
+{
+	struct device_node *ports, *port;
+
+	ports = of_get_child_by_name(node, "ports");
+	if (ports)
+		node = ports;
+
+	port = of_get_child_by_name(node, "port");
+	of_node_put(ports);
+
+	return port;
+}
+EXPORT_SYMBOL(of_graph_get_local_port);
+
 int of_graph_get_endpoint_count(const struct device_node *np)
 {
 	struct device_node *endpoint;
include/linux/of_graph.h +7 -0
index 01038a6aade0..1fdeb72c7765 100644
@@ -54,6 +54,7 @@ struct device_node *of_graph_get_remote_port_parent(
 struct device_node *of_graph_get_remote_port(const struct device_node *node);
 struct device_node *of_graph_get_remote_node(const struct device_node *node,
 					     u32 port, u32 endpoint);
+struct device_node *of_graph_get_local_port(const struct device_node *node);
 #else
 
 static inline int of_graph_parse_endpoint(const struct device_node *node,
@@ -116,6 +117,12 @@ static inline struct device_node *of_graph_get_remote_node(
 	return NULL;
 }
 
+static inline struct device_node *of_graph_get_local_port(
+					const struct device_node *node)
+{
+	return NULL;
+}
+
 #endif /* CONFIG_OF */
 
 #endif /* __LINUX_OF_GRAPH_H */
Signature · 1 line
2.26.0
maintainer Reviewed-by on v5 1/6
#2 lore raw

Re: [PATCH v5 1/6] of_graph: add of_graph_get_local_port()

Quoted 8 lines · Dmitry Osipenko

In some case, like a DRM display code for example, it's useful to silently check whether port node exists at all in a device-tree before proceeding with parsing the graph.

This patch adds of_graph_get_local_port() which returns pointer to a local port node, or NULL if graph isn't specified in a device-tree for a given device node.

Quoted 6 lines
---
 drivers/of/property.c    | 32 +++++++++++++++++++++++---------
 include/linux/of_graph.h |  7 +++++++
 2 files changed, 30 insertions(+), 9 deletions(-)
Reviewed-by on v5 1/6
#3 lore raw

Re: [PATCH v5 1/6] of_graph: add of_graph_get_local_port()

In reply to Dmitry Osipenko

Hi Dmitry

Quoted 9 lines · Dmitry Osipenko

In some case, like a DRM display code for example, it's useful to silently check whether port node exists at all in a device-tree before proceeding with parsing the graph.

This patch adds of_graph_get_local_port() which returns pointer to a local port node, or NULL if graph isn't specified in a device-tree for a given device node.

Nice little helper function.

Rob - OK to commit to drm-misc-next?

Sam

Quoted 87 lines
---
 drivers/of/property.c    | 32 +++++++++++++++++++++++---------
 include/linux/of_graph.h |  7 +++++++
 2 files changed, 30 insertions(+), 9 deletions(-)
drivers/of/property.c +23 -9
index 252e4f600155..5dbeccaabb86 100644
@@ -608,15 +608,7 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
 	 * parent port node.
 	 */
 	if (!prev) {
-		struct device_node *node;
-
-		node = of_get_child_by_name(parent, "ports");
-		if (node)
-			parent = node;
-
-		port = of_get_child_by_name(parent, "port");
-		of_node_put(node);
-
+		port = of_graph_get_local_port(parent);
 		if (!port) {
 			pr_err("graph: no port node found in %pOF\n", parent);
 			return NULL;
@@ -765,6 +757,28 @@ struct device_node *of_graph_get_remote_port(const struct device_node *node)
 }
 EXPORT_SYMBOL(of_graph_get_remote_port);
 
+/**
+ * of_graph_get_local_port() - get local port node
+ * @node: pointer to a local endpoint device_node
+ *
+ * Return: First local port node associated with local endpoint node linked
+ *	   to @node. Use of_node_put() on it when done.
+ */
+struct device_node *of_graph_get_local_port(const struct device_node *node)
+{
+	struct device_node *ports, *port;
+
+	ports = of_get_child_by_name(node, "ports");
+	if (ports)
+		node = ports;
+
+	port = of_get_child_by_name(node, "port");
+	of_node_put(ports);
+
+	return port;
+}
+EXPORT_SYMBOL(of_graph_get_local_port);
+
 int of_graph_get_endpoint_count(const struct device_node *np)
 {
 	struct device_node *endpoint;
include/linux/of_graph.h +7 -0
index 01038a6aade0..1fdeb72c7765 100644
@@ -54,6 +54,7 @@ struct device_node *of_graph_get_remote_port_parent(
 struct device_node *of_graph_get_remote_port(const struct device_node *node);
 struct device_node *of_graph_get_remote_node(const struct device_node *node,
 					     u32 port, u32 endpoint);
+struct device_node *of_graph_get_local_port(const struct device_node *node);
 #else
 
 static inline int of_graph_parse_endpoint(const struct device_node *node,
@@ -116,6 +117,12 @@ static inline struct device_node *of_graph_get_remote_node(
 	return NULL;
 }
 
+static inline struct device_node *of_graph_get_local_port(
+					const struct device_node *node)
+{
+	return NULL;
+}
+
 #endif /* CONFIG_OF */
 
 #endif /* __LINUX_OF_GRAPH_H */
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#4 lore raw

Re: [PATCH v5 1/6] of_graph: add of_graph_get_local_port()

Quoted 12 lines · Sam Ravnborg

Hi Dmitry

Quoted 8 lines · Dmitry Osipenko

In some case, like a DRM display code for example, it's useful to silently check whether port node exists at all in a device-tree before proceeding with parsing the graph.

This patch adds of_graph_get_local_port() which returns pointer to a local port node, or NULL if graph isn't specified in a device-tree for a given device node.

Quoted 5 lines
Quoted 1 line

Nice little helper function.

Rob - OK to commit to drm-misc-next?

Yes, that's why I gave my R-by.

Rob

#5 lore raw

PATCH v5 2/6 drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence

In reply to Dmitry Osipenko

When graph isn't defined in a device-tree, the of_graph_get_remote_node() prints a noisy error message, telling that port node is not found. This is undesirable behaviour in our case because absence of a panel/bridge graph is a valid case. Let's check presence of the local port in a device-tree before proceeding with parsing the graph.

---
 drivers/gpu/drm/drm_of.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)
drivers/gpu/drm/drm_of.c +12 -1
index b50b44e76279..e0652c38f357 100644
@@ -239,13 +239,24 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
 				struct drm_bridge **bridge)
 {
 	int ret = -EPROBE_DEFER;
-	struct device_node *remote;
+	struct device_node *local, *remote;
 
 	if (!panel && !bridge)
 		return -EINVAL;
 	if (panel)
 		*panel = NULL;
 
+	/*
+	 * of_graph_get_remote_node() produces a noisy error message if port
+	 * node isn't found and the absence of the port is a legit case here,
+	 * so at first we silently check presence of the local port.
+	 */
+	local = of_graph_get_local_port(np);
+	if (!local)
+		return -ENODEV;
+
+	of_node_put(local);
+
 	remote = of_graph_get_remote_node(np, port, endpoint);
 	if (!remote)
 		return -ENODEV;
Signature · 1 line
2.26.0
Reviewed-by on v5 2/6
#6 lore raw

Re: [PATCH v5 2/6] drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence

Quoted 7 lines · Dmitry Osipenko

When graph isn't defined in a device-tree, the of_graph_get_remote_node() prints a noisy error message, telling that port node is not found. This is undesirable behaviour in our case because absence of a panel/bridge graph is a valid case. Let's check presence of the local port in a device-tree before proceeding with parsing the graph.

Quoted 41 lines
---
 drivers/gpu/drm/drm_of.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)
drivers/gpu/drm/drm_of.c +12 -1
index b50b44e76279..e0652c38f357 100644
@@ -239,13 +239,24 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
 				struct drm_bridge **bridge)
 {
 	int ret = -EPROBE_DEFER;
-	struct device_node *remote;
+	struct device_node *local, *remote;
 
 	if (!panel && !bridge)
 		return -EINVAL;
 	if (panel)
 		*panel = NULL;
 
+	/*
+	 * of_graph_get_remote_node() produces a noisy error message if port
+	 * node isn't found and the absence of the port is a legit case here,
+	 * so at first we silently check presence of the local port.
+	 */
+	local = of_graph_get_local_port(np);
+	if (!local)
+		return -ENODEV;
+
+	of_node_put(local);
+
 	remote = of_graph_get_remote_node(np, port, endpoint);
 	if (!remote)
 		return -ENODEV;
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#7 lore raw

Re: [PATCH v5 2/6] drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence

06.05.2020 19:41, Sam Ravnborg пишет:

Quoted 9 lines · Dmitry Osipenko
Quoted 7 lines

When graph isn't defined in a device-tree, the of_graph_get_remote_node() prints a noisy error message, telling that port node is not found. This is undesirable behaviour in our case because absence of a panel/bridge graph is a valid case. Let's check presence of the local port in a device-tree before proceeding with parsing the graph.

Thank you again for taking a look at these patches!

#8 lore raw

PATCH v5 3/6 drm/tegra: output: Don't leak OF node on error

In reply to Dmitry Osipenko

The OF node should be put before returning error in tegra_output_probe(), otherwise node's refcount will be leaked.

---
 drivers/gpu/drm/tegra/output.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)
drivers/gpu/drm/tegra/output.c +4 -5
index e36e5e7c2f69..a6a711d54e88 100644
@@ -102,10 +102,10 @@ int tegra_output_probe(struct tegra_output *output)
 	panel = of_parse_phandle(output->of_node, "nvidia,panel", 0);
 	if (panel) {
 		output->panel = of_drm_find_panel(panel);
+		of_node_put(panel);
+
 		if (IS_ERR(output->panel))
 			return PTR_ERR(output->panel);
-
-		of_node_put(panel);
 	}
 
 	output->edid = of_get_property(output->of_node, "nvidia,edid", &size);
@@ -113,13 +113,12 @@ int tegra_output_probe(struct tegra_output *output)
 	ddc = of_parse_phandle(output->of_node, "nvidia,ddc-i2c-bus", 0);
 	if (ddc) {
 		output->ddc = of_find_i2c_adapter_by_node(ddc);
+		of_node_put(ddc);
+
 		if (!output->ddc) {
 			err = -EPROBE_DEFER;
-			of_node_put(ddc);
 			return err;
 		}
-
-		of_node_put(ddc);
 	}
 
 	output->hpd_gpio = devm_gpiod_get_from_of_node(output->dev,
Signature · 1 line
2.26.0
Reviewed-by on v5 3/6
#9 lore raw

Re: [PATCH v5 3/6] drm/tegra: output: Don't leak OF node on error

Quoted 5 lines · Dmitry Osipenko

The OF node should be put before returning error in tegra_output_probe(), otherwise node's refcount will be leaked.

Quoted 44 lines
---
 drivers/gpu/drm/tegra/output.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)
drivers/gpu/drm/tegra/output.c +4 -5
index e36e5e7c2f69..a6a711d54e88 100644
@@ -102,10 +102,10 @@ int tegra_output_probe(struct tegra_output *output)
 	panel = of_parse_phandle(output->of_node, "nvidia,panel", 0);
 	if (panel) {
 		output->panel = of_drm_find_panel(panel);
+		of_node_put(panel);
+
 		if (IS_ERR(output->panel))
 			return PTR_ERR(output->panel);
-
-		of_node_put(panel);
 	}
 
 	output->edid = of_get_property(output->of_node, "nvidia,edid", &size);
@@ -113,13 +113,12 @@ int tegra_output_probe(struct tegra_output *output)
 	ddc = of_parse_phandle(output->of_node, "nvidia,ddc-i2c-bus", 0);
 	if (ddc) {
 		output->ddc = of_find_i2c_adapter_by_node(ddc);
+		of_node_put(ddc);
+
 		if (!output->ddc) {
 			err = -EPROBE_DEFER;
-			of_node_put(ddc);
 			return err;
 		}
-
-		of_node_put(ddc);
 	}
 
 	output->hpd_gpio = devm_gpiod_get_from_of_node(output->dev,
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#10 lore raw

PATCH v5 4/6 drm/tegra: output: Support DRM bridges

In reply to Dmitry Osipenko

Newer Tegra device-trees will specify a video output graph which involves a bridge. This patch adds initial support for the DRM bridges to the Tegra DRM output.

---
 drivers/gpu/drm/tegra/drm.h    |  2 ++
 drivers/gpu/drm/tegra/output.c | 12 ++++++++++++
 2 files changed, 14 insertions(+)
drivers/gpu/drm/tegra/drm.h +2 -0
index 804869799305..cccd368b6752 100644
@@ -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;
drivers/gpu/drm/tegra/output.c +12 -0
index a6a711d54e88..ccd1421f1b24 100644
@@ -5,6 +5,7 @@
  */
 
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_simple_kms_helper.h>
 
@@ -99,8 +100,19 @@ int tegra_output_probe(struct tegra_output *output)
 	if (!output->of_node)
 		output->of_node = output->dev->of_node;
 
+	err = drm_of_find_panel_or_bridge(output->of_node, -1, -1,
+					  &output->panel, &output->bridge);
+	if (err && err != -ENODEV)
+		return err;
+
 	panel = of_parse_phandle(output->of_node, "nvidia,panel", 0);
 	if (panel) {
+		/*
+		 * Don't mix nvidia,panel phandle with the graph in a
+		 * device-tree.
+		 */
+		WARN_ON(output->panel || output->bridge);
+
 		output->panel = of_drm_find_panel(panel);
 		of_node_put(panel);
 
Signature · 1 line
2.26.0
Acked-by on v5 4/6
#11 lore raw

Re: [PATCH v5 4/6] drm/tegra: output: Support DRM bridges

Quoted 5 lines · Dmitry Osipenko

Newer Tegra device-trees will specify a video output graph which involves a bridge. This patch adds initial support for the DRM bridges to the Tegra DRM output.

Quoted 64 lines
---
 drivers/gpu/drm/tegra/drm.h    |  2 ++
 drivers/gpu/drm/tegra/output.c | 12 ++++++++++++
 2 files changed, 14 insertions(+)
drivers/gpu/drm/tegra/drm.h +2 -0
index 804869799305..cccd368b6752 100644
@@ -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;
drivers/gpu/drm/tegra/output.c +12 -0
index a6a711d54e88..ccd1421f1b24 100644
@@ -5,6 +5,7 @@
  */
 
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_simple_kms_helper.h>
 
@@ -99,8 +100,19 @@ int tegra_output_probe(struct tegra_output *output)
 	if (!output->of_node)
 		output->of_node = output->dev->of_node;
 
+	err = drm_of_find_panel_or_bridge(output->of_node, -1, -1,
+					  &output->panel, &output->bridge);
+	if (err && err != -ENODEV)
+		return err;
+
 	panel = of_parse_phandle(output->of_node, "nvidia,panel", 0);
 	if (panel) {
+		/*
+		 * Don't mix nvidia,panel phandle with the graph in a
+		 * device-tree.
+		 */
+		WARN_ON(output->panel || output->bridge);
+
 		output->panel = of_drm_find_panel(panel);
 		of_node_put(panel);
 
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#12 lore raw

PATCH v5 5/6 drm/tegra: output: rgb: Support LVDS encoder bridge

In reply to Dmitry Osipenko

Newer Tegra device-trees will specify a video output graph, which involves LVDS encoder bridge. This patch adds support for the LVDS encoder bridge to the RGB output, allowing us to model the display hardware properly.

---
 drivers/gpu/drm/tegra/rgb.c | 58 +++++++++++++++++++++++++++++++------
 1 file changed, 49 insertions(+), 9 deletions(-)
drivers/gpu/drm/tegra/rgb.c +49 -9
index 0562a7eb793f..9a7024ec96bc 100644
@@ -7,6 +7,7 @@
 #include <linux/clk.h>
 
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_bridge_connector.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_simple_kms_helper.h>
 
@@ -267,24 +268,63 @@ int tegra_dc_rgb_remove(struct tegra_dc *dc)
 int tegra_dc_rgb_init(struct drm_device *drm, struct tegra_dc *dc)
 {
 	struct tegra_output *output = dc->rgb;
+	struct drm_connector *connector;
 	int err;
 
 	if (!dc->rgb)
 		return -ENODEV;
 
-	drm_connector_init(drm, &output->connector, &tegra_rgb_connector_funcs,
-			   DRM_MODE_CONNECTOR_LVDS);
-	drm_connector_helper_add(&output->connector,
-				 &tegra_rgb_connector_helper_funcs);
-	output->connector.dpms = DRM_MODE_DPMS_OFF;
-
 	drm_simple_encoder_init(drm, &output->encoder, DRM_MODE_ENCODER_LVDS);
 	drm_encoder_helper_add(&output->encoder,
 			       &tegra_rgb_encoder_helper_funcs);
 
-	drm_connector_attach_encoder(&output->connector,
-					  &output->encoder);
-	drm_connector_register(&output->connector);
+	/*
+	 * Tegra devices that have LVDS panel utilize LVDS encoder bridge
+	 * for converting up to 28 LCD LVTTL lanes into 5/4 LVDS lanes that
+	 * go to display panel's receiver.
+	 *
+	 * Encoder usually have a power-down control which needs to be enabled
+	 * in order to transmit 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 utilize LVDS encoder bridge, which provides
+	 * us with a connector and handles the display panel.
+	 *
+	 * For older device-trees we fall back to our own connector and use
+	 * nvidia,panel phandle.
+	 */
+	if (output->bridge) {
+		err = drm_bridge_attach(&output->encoder, output->bridge,
+					NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+		if (err) {
+			dev_err(output->dev, "failed to attach bridge: %d\n",
+				err);
+			return err;
+		}
+
+		connector = drm_bridge_connector_init(drm, &output->encoder);
+		if (IS_ERR(connector)) {
+			dev_err(output->dev,
+				"failed to initialize bridge connector: %pe\n",
+				connector);
+			return PTR_ERR(connector);
+		}
+
+		drm_connector_attach_encoder(connector, &output->encoder);
+	} else {
+		drm_connector_init(drm, &output->connector,
+				   &tegra_rgb_connector_funcs,
+				   DRM_MODE_CONNECTOR_LVDS);
+		drm_connector_helper_add(&output->connector,
+					 &tegra_rgb_connector_helper_funcs);
+		output->connector.dpms = DRM_MODE_DPMS_OFF;
+
+		drm_connector_attach_encoder(&output->connector,
+					     &output->encoder);
+		drm_connector_register(&output->connector);
+	}
 
 	err = tegra_output_init(drm, output);
 	if (err < 0) {
Signature · 1 line
2.26.0
Acked-by on v5 5/6
#13 lore raw

Re: [PATCH v5 5/6] drm/tegra: output: rgb: Support LVDS encoder bridge

Quoted 6 lines · Dmitry Osipenko

Newer Tegra device-trees will specify a video output graph, which involves LVDS encoder bridge. This patch adds support for the LVDS encoder bridge to the RGB output, allowing us to model the display hardware properly.

Quoted 96 lines
---
 drivers/gpu/drm/tegra/rgb.c | 58 +++++++++++++++++++++++++++++++------
 1 file changed, 49 insertions(+), 9 deletions(-)
drivers/gpu/drm/tegra/rgb.c +49 -9
index 0562a7eb793f..9a7024ec96bc 100644
@@ -7,6 +7,7 @@
 #include <linux/clk.h>
 
 #include <drm/drm_atomic_helper.h>
+#include <drm/drm_bridge_connector.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_simple_kms_helper.h>
 
@@ -267,24 +268,63 @@ int tegra_dc_rgb_remove(struct tegra_dc *dc)
 int tegra_dc_rgb_init(struct drm_device *drm, struct tegra_dc *dc)
 {
 	struct tegra_output *output = dc->rgb;
+	struct drm_connector *connector;
 	int err;
 
 	if (!dc->rgb)
 		return -ENODEV;
 
-	drm_connector_init(drm, &output->connector, &tegra_rgb_connector_funcs,
-			   DRM_MODE_CONNECTOR_LVDS);
-	drm_connector_helper_add(&output->connector,
-				 &tegra_rgb_connector_helper_funcs);
-	output->connector.dpms = DRM_MODE_DPMS_OFF;
-
 	drm_simple_encoder_init(drm, &output->encoder, DRM_MODE_ENCODER_LVDS);
 	drm_encoder_helper_add(&output->encoder,
 			       &tegra_rgb_encoder_helper_funcs);
 
-	drm_connector_attach_encoder(&output->connector,
-					  &output->encoder);
-	drm_connector_register(&output->connector);
+	/*
+	 * Tegra devices that have LVDS panel utilize LVDS encoder bridge
+	 * for converting up to 28 LCD LVTTL lanes into 5/4 LVDS lanes that
+	 * go to display panel's receiver.
+	 *
+	 * Encoder usually have a power-down control which needs to be enabled
+	 * in order to transmit 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 utilize LVDS encoder bridge, which provides
+	 * us with a connector and handles the display panel.
+	 *
+	 * For older device-trees we fall back to our own connector and use
+	 * nvidia,panel phandle.
+	 */
+	if (output->bridge) {
+		err = drm_bridge_attach(&output->encoder, output->bridge,
+					NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+		if (err) {
+			dev_err(output->dev, "failed to attach bridge: %d\n",
+				err);
+			return err;
+		}
+
+		connector = drm_bridge_connector_init(drm, &output->encoder);
+		if (IS_ERR(connector)) {
+			dev_err(output->dev,
+				"failed to initialize bridge connector: %pe\n",
+				connector);
+			return PTR_ERR(connector);
+		}
+
+		drm_connector_attach_encoder(connector, &output->encoder);
+	} else {
+		drm_connector_init(drm, &output->connector,
+				   &tegra_rgb_connector_funcs,
+				   DRM_MODE_CONNECTOR_LVDS);
+		drm_connector_helper_add(&output->connector,
+					 &tegra_rgb_connector_helper_funcs);
+		output->connector.dpms = DRM_MODE_DPMS_OFF;
+
+		drm_connector_attach_encoder(&output->connector,
+					     &output->encoder);
+		drm_connector_register(&output->connector);
+	}
 
 	err = tegra_output_init(drm, output);
 	if (err < 0) {
Signature · 6 lines
2.26.0

_______________________________________________
dri-devel mailing list
[email protected]
https://lists.freedesktop.org/mailman/listinfo/dri-devel
#14 lore raw

PATCH v5 6/6 drm/tegra: output: rgb: Wrap directly-connected panel into DRM bridge

In reply to Dmitry Osipenko

Currently Tegra DRM driver manually manages display panel, but this management could be moved out into DRM core if we'll wrap panel into DRM bridge. This patch wraps RGB panel into a DRM bridge and removes manual handling of the panel from the RGB output code.

---
 drivers/gpu/drm/tegra/rgb.c | 53 +++++++++++++------------------------
 1 file changed, 18 insertions(+), 35 deletions(-)
drivers/gpu/drm/tegra/rgb.c +18 -35
index 9a7024ec96bc..a4c5a6066c54 100644
@@ -8,7 +8,6 @@
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge_connector.h>
-#include <drm/drm_panel.h>
 #include <drm/drm_simple_kms_helper.h>
 
 #include "drm.h"
@@ -86,15 +85,6 @@ static void tegra_dc_write_regs(struct tegra_dc *dc,
 		tegra_dc_writel(dc, table[i].value, table[i].offset);
 }
 
-static const struct drm_connector_funcs tegra_rgb_connector_funcs = {
-	.reset = drm_atomic_helper_connector_reset,
-	.detect = tegra_output_connector_detect,
-	.fill_modes = drm_helper_probe_single_connector_modes,
-	.destroy = tegra_output_connector_destroy,
-	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
-	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
-};
-
 static enum drm_mode_status
 tegra_rgb_connector_mode_valid(struct drm_connector *connector,
 			       struct drm_display_mode *mode)
@@ -117,14 +107,8 @@ static void tegra_rgb_encoder_disable(struct drm_encoder *encoder)
 	struct tegra_output *output = encoder_to_output(encoder);
 	struct tegra_rgb *rgb = to_rgb(output);
 
-	if (output->panel)
-		drm_panel_disable(output->panel);
-
 	tegra_dc_write_regs(rgb->dc, rgb_disable, ARRAY_SIZE(rgb_disable));
 	tegra_dc_commit(rgb->dc);
-
-	if (output->panel)
-		drm_panel_unprepare(output->panel);
 }
 
 static void tegra_rgb_encoder_enable(struct drm_encoder *encoder)
@@ -133,9 +117,6 @@ static void tegra_rgb_encoder_enable(struct drm_encoder *encoder)
 	struct tegra_rgb *rgb = to_rgb(output);
 	u32 value;
 
-	if (output->panel)
-		drm_panel_prepare(output->panel);
-
 	tegra_dc_write_regs(rgb->dc, rgb_enable, ARRAY_SIZE(rgb_enable));
 
 	value = DE_SELECT_ACTIVE | DE_CONTROL_NORMAL;
@@ -157,9 +138,6 @@ static void tegra_rgb_encoder_enable(struct drm_encoder *encoder)
 	tegra_dc_writel(rgb->dc, value, DC_DISP_SHIFT_CLOCK_OPTIONS);
 
 	tegra_dc_commit(rgb->dc);
-
-	if (output->panel)
-		drm_panel_enable(output->panel);
 }
 
 static int
@@ -278,6 +256,23 @@ int tegra_dc_rgb_init(struct drm_device *drm, struct tegra_dc *dc)
 	drm_encoder_helper_add(&output->encoder,
 			       &tegra_rgb_encoder_helper_funcs);
 
+	/*
+	 * Wrap directly-connected panel into DRM bridge in order to let
+	 * DRM core to handle panel for us.
+	 */
+	if (output->panel) {
+		output->bridge = devm_drm_panel_bridge_add(output->dev,
+							   output->panel);
+		if (IS_ERR(output->bridge)) {
+			dev_err(output->dev,
+				"failed to wrap panel into bridge: %pe\n",
+				output->bridge);
+			return PTR_ERR(output->bridge);
+		}
+
+		output->panel = NULL;
+	}
+
 	/*
 	 * Tegra devices that have LVDS panel utilize LVDS encoder bridge
 	 * for converting up to 28 LCD LVTTL lanes into 5/4 LVDS lanes that
@@ -292,8 +287,7 @@ int tegra_dc_rgb_init(struct drm_device *drm, struct tegra_dc *dc)
 	 * Newer device-trees utilize LVDS encoder bridge, which provides
 	 * us with a connector and handles the display panel.
 	 *
-	 * For older device-trees we fall back to our own connector and use
-	 * nvidia,panel phandle.
+	 * For older device-trees we wrapped panel into the panel-bridge.
 	 */
 	if (output->bridge) {
 		err = drm_bridge_attach(&output->encoder, output->bridge,
@@ -313,17 +307,6 @@ int tegra_dc_rgb_init(struct drm_device *drm, struct tegra_dc *dc)
 		}
 
 		drm_connector_attach_encoder(connector, &output->encoder);
-	} else {
-		drm_connector_init(drm, &output->connector,
-				   &tegra_rgb_connector_funcs,
-				   DRM_MODE_CONNECTOR_LVDS);
-		drm_connector_helper_add(&output->connector,
-					 &tegra_rgb_connector_helper_funcs);
-		output->connector.dpms = DRM_MODE_DPMS_OFF;
-
-		drm_connector_attach_encoder(&output->connector,
-					     &output->encoder);
-		drm_connector_register(&output->connector);
 	}
 
 	err = tegra_output_init(drm, output);
Signature · 1 line
2.26.0
Acked-by on v5 6/6
#15 lore raw

Re: [PATCH v5 6/6] drm/tegra: output: rgb: Wrap directly-connected panel into DRM bridge

Hi Dmitry

Quoted 7 lines · Dmitry Osipenko

Currently Tegra DRM driver manually manages display panel, but this management could be moved out into DRM core if we'll wrap panel into DRM bridge. This patch wraps RGB panel into a DRM bridge and removes manual handling of the panel from the RGB output code.

This resulted in the expected simplifications - good.

Quoted 126 lines
---
 drivers/gpu/drm/tegra/rgb.c | 53 +++++++++++++------------------------
 1 file changed, 18 insertions(+), 35 deletions(-)
drivers/gpu/drm/tegra/rgb.c +18 -35
index 9a7024ec96bc..a4c5a6066c54 100644
@@ -8,7 +8,6 @@
 
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_bridge_connector.h>
-#include <drm/drm_panel.h>
 #include <drm/drm_simple_kms_helper.h>
 
 #include "drm.h"
@@ -86,15 +85,6 @@ static void tegra_dc_write_regs(struct tegra_dc *dc,
 		tegra_dc_writel(dc, table[i].value, table[i].offset);
 }
 
-static const struct drm_connector_funcs tegra_rgb_connector_funcs = {
-	.reset = drm_atomic_helper_connector_reset,
-	.detect = tegra_output_connector_detect,
-	.fill_modes = drm_helper_probe_single_connector_modes,
-	.destroy = tegra_output_connector_destroy,
-	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
-	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
-};
-
 static enum drm_mode_status
 tegra_rgb_connector_mode_valid(struct drm_connector *connector,
 			       struct drm_display_mode *mode)
@@ -117,14 +107,8 @@ static void tegra_rgb_encoder_disable(struct drm_encoder *encoder)
 	struct tegra_output *output = encoder_to_output(encoder);
 	struct tegra_rgb *rgb = to_rgb(output);
 
-	if (output->panel)
-		drm_panel_disable(output->panel);
-
 	tegra_dc_write_regs(rgb->dc, rgb_disable, ARRAY_SIZE(rgb_disable));
 	tegra_dc_commit(rgb->dc);
-
-	if (output->panel)
-		drm_panel_unprepare(output->panel);
 }
 
 static void tegra_rgb_encoder_enable(struct drm_encoder *encoder)
@@ -133,9 +117,6 @@ static void tegra_rgb_encoder_enable(struct drm_encoder *encoder)
 	struct tegra_rgb *rgb = to_rgb(output);
 	u32 value;
 
-	if (output->panel)
-		drm_panel_prepare(output->panel);
-
 	tegra_dc_write_regs(rgb->dc, rgb_enable, ARRAY_SIZE(rgb_enable));
 
 	value = DE_SELECT_ACTIVE | DE_CONTROL_NORMAL;
@@ -157,9 +138,6 @@ static void tegra_rgb_encoder_enable(struct drm_encoder *encoder)
 	tegra_dc_writel(rgb->dc, value, DC_DISP_SHIFT_CLOCK_OPTIONS);
 
 	tegra_dc_commit(rgb->dc);
-
-	if (output->panel)
-		drm_panel_enable(output->panel);
 }
 
 static int
@@ -278,6 +256,23 @@ int tegra_dc_rgb_init(struct drm_device *drm, struct tegra_dc *dc)
 	drm_encoder_helper_add(&output->encoder,
 			       &tegra_rgb_encoder_helper_funcs);
 
+	/*
+	 * Wrap directly-connected panel into DRM bridge in order to let
+	 * DRM core to handle panel for us.
+	 */
+	if (output->panel) {
+		output->bridge = devm_drm_panel_bridge_add(output->dev,
+							   output->panel);
+		if (IS_ERR(output->bridge)) {
+			dev_err(output->dev,
+				"failed to wrap panel into bridge: %pe\n",
+				output->bridge);
+			return PTR_ERR(output->bridge);
+		}
+
+		output->panel = NULL;
+	}
+
 	/*
 	 * Tegra devices that have LVDS panel utilize LVDS encoder bridge
 	 * for converting up to 28 LCD LVTTL lanes into 5/4 LVDS lanes that
@@ -292,8 +287,7 @@ int tegra_dc_rgb_init(struct drm_device *drm, struct tegra_dc *dc)
 	 * Newer device-trees utilize LVDS encoder bridge, which provides
 	 * us with a connector and handles the display panel.
 	 *
-	 * For older device-trees we fall back to our own connector and use
-	 * nvidia,panel phandle.
+	 * For older device-trees we wrapped panel into the panel-bridge.
 	 */
 	if (output->bridge) {
 		err = drm_bridge_attach(&output->encoder, output->bridge,
@@ -313,17 +307,6 @@ int tegra_dc_rgb_init(struct drm_device *drm, struct tegra_dc *dc)
 		}
 
 		drm_connector_attach_encoder(connector, &output->encoder);
-	} else {
-		drm_connector_init(drm, &output->connector,
-				   &tegra_rgb_connector_funcs,
-				   DRM_MODE_CONNECTOR_LVDS);
-		drm_connector_helper_add(&output->connector,
-					 &tegra_rgb_connector_helper_funcs);
-		output->connector.dpms = DRM_MODE_DPMS_OFF;
-
-		drm_connector_attach_encoder(&output->connector,
-					     &output->encoder);
-		drm_connector_register(&output->connector);
 	}
 
 	err = tegra_output_init(drm, output);
Signature · 6 lines
2.26.0

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dri-devel mailing list
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#16 lore raw

Re: [PATCH v5 6/6] drm/tegra: output: rgb: Wrap directly-connected panel into DRM bridge

25.04.2020 20:02, Sam Ravnborg пишет:

Quoted 8 lines

Hi Dmitry

Quoted 5 lines · Dmitry Osipenko

Currently Tegra DRM driver manually manages display panel, but this management could be moved out into DRM core if we'll wrap panel into DRM bridge. This patch wraps RGB panel into a DRM bridge and removes manual handling of the panel from the RGB output code.

Quoted 5 lines
Quoted 2 lines

This resulted in the expected simplifications - good.

Hello Sam,

Thank you for taking a look at this patch! :)

#17 lore raw
In reply to Dmitry Osipenko

18.04.2020 20:06, Dmitry Osipenko пишет:

Quoted 49 lines

Hello,

This series adds initial support for the DRM bridges to NVIDIA Tegra DRM driver. This is required by newer device-trees where we model the LVDS encoder bridge properly.

Changelog:

v5: - Added new patches that make drm_of_find_panel_or_bridge() more usable
if graph isn't defined in a device-tree:

of_graph: add of_graph_get_local_port()
drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence

- Updated "Support DRM bridges" patch to use drm_of_find_panel_or_bridge() directly and added WARN_ON(output->panel || output->bridge) sanity-check.

- Added new "Wrap directly-connected panel into DRM bridge" patch, as was suggested by Laurent Pinchart.

v4: - Following review comments that were made by Laurent Pinchart to the v3,
we now create and use the "bridge connector".

v3: - Following recommendation from Sam Ravnborg, the new bridge attachment
model is now being used, i.e. we ask bridge to *not* create a connector using the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag.

- The bridge is now created only for the RGB (LVDS) output, and only when necessary. For now we don't need bridges for HDMI or DSI outputs.

- I noticed that we're leaking OF node in the panel's error code path, this is fixed now by the new patch "Don't leak OF node on error".

v2: - Added the new "rgb: Don't register connector if bridge is used"
patch, which hides the unused connector provided by the Tegra DRM driver when bridge is used, since bridge provides its own connector to us.

- Please notice that the first "Support DRM bridges" patch was previously sent out as a standalone v1 change.

Dmitry Osipenko (6):
of_graph: add of_graph_get_local_port()
drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence drm/tegra: output: Don't leak OF node on error
drm/tegra: output: Support DRM bridges
drm/tegra: output: rgb: Support LVDS encoder bridge drm/tegra: output: rgb: Wrap directly-connected panel into DRM bridge

Quoted 8 lines
 drivers/gpu/drm/drm_of.c       | 13 +++++-
 drivers/gpu/drm/tegra/drm.h    |  2 +
 drivers/gpu/drm/tegra/output.c | 21 +++++++--
 drivers/gpu/drm/tegra/rgb.c    | 85 +++++++++++++++++++++-------------
 drivers/of/property.c          | 32 +++++++++----
 include/linux/of_graph.h       |  7 +++
 6 files changed, 114 insertions(+), 46 deletions(-)

Hello Thierry,

Do you you have any objections to this series?