drm/panel: Add Magnachip D53E6EA8966 Panel Controller

From: Chris Morgan <[email protected]>

Add helper function to find DSI host for devices where DSI panel is not a minor of a DSI bus (such as the Samsung AMS495QA01 panel or the official Raspberry Pi touchscreen display).

Signed-off-by Chris Morgan <[email protected]>

Signed-off-by Maya Matuszczyk <[email protected]>

---
 drivers/gpu/drm/drm_of.c | 70 ++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_of.h     | 10 ++++++
 2 files changed, 80 insertions(+)

drivers/gpu/drm/drm_of.c +46 -0

index 7bbcb999bb75..6c2c97a716fe 100644
@@ -10,6 +10,7 @@
 #include <drm/drm_crtc.h>
 #include <drm/drm_device.h>
 #include <drm/drm_encoder.h>
+#include <drm/drm_mipi_dsi.h>
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 

@@ -493,3 +494,72 @@ int drm_of_get_data_lanes_count_ep(const struct device_node *port,
 	return ret;
 }
 EXPORT_SYMBOL_GPL(drm_of_get_data_lanes_count_ep);
+
+#if IS_ENABLED(CONFIG_DRM_MIPI_DSI)
+
+/**
+ * drm_of_get_dsi_bus - find the DSI bus for a given device
+ * @dev: parent device of display (SPI, I2C)
+ * @info: DSI device info to be updated with DSI node. This is optional
+ * and if not needed can be NULL.
+ *
+ * Gets parent DSI bus for a DSI device controlled through a bus other
+ * than MIPI-DCS (SPI, I2C, etc.) using the Device Tree.
+ *
+ * Returns pointer to mipi_dsi_host if successful, -EINVAL if the
+ * request is unsupported, -EPROBE_DEFER if the DSI host is found but
+ * not available, or -ENODEV otherwise.
+ */
+struct mipi_dsi_host *drm_of_get_dsi_bus(struct device *dev,
+					 struct mipi_dsi_device_info *info)
+{
+	struct mipi_dsi_host *dsi_host;
+	struct device_node *endpoint, *dsi_host_node;
+
+	/*
+	 * Get first endpoint child from device.
+	 */
+	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
+	if (!endpoint)
+		return ERR_PTR(-ENODEV);
+
+	/*
+	 * Follow the first endpoint to get the DSI host node.
+	 */
+	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
+	if (!dsi_host_node)
+		goto error;
+
+	/*
+	 * Get the DSI host from the DSI host node. If we get an error
+	 * or the return is null assume we're not ready to probe just
+	 * yet. Release the DSI host node since we're done with it.
+	 */
+	dsi_host = of_find_mipi_dsi_host_by_node(dsi_host_node);
+	of_node_put(dsi_host_node);
+	if (IS_ERR_OR_NULL(dsi_host)) {
+		of_node_put(endpoint);

include/drm/drm_of.h +4 -0

@@ -15,6 +15,8 @@ struct drm_encoder;
 struct drm_panel;
 struct drm_bridge;
 struct device_node;
+struct mipi_dsi_device_info;
+struct mipi_dsi_host;
 
 /**
  * enum drm_lvds_dual_link_pixels - Pixel order of an LVDS dual-link connection

@@ -56,6 +58,8 @@ int drm_of_get_data_lanes_count_ep(const struct device_node *port,
 				   int port_reg, int reg,
 				   const unsigned int min,
 				   const unsigned int max);
+struct mipi_dsi_host *drm_of_get_dsi_bus(struct device *dev,
+					 struct mipi_dsi_device_info *info);
 #else
 static inline uint32_t drm_of_crtc_port_mask(struct drm_device *dev,
 					  struct device_node *port)

Hi,

Quoted 74 lines · Chris Morgan

From: Chris Morgan <[email protected]>

Add helper function to find DSI host for devices where DSI panel is not a minor of a DSI bus (such as the Samsung AMS495QA01 panel or the official Raspberry Pi touchscreen display).

Signed-off-by Chris Morgan <[email protected]>

Signed-off-by Maya Matuszczyk <[email protected]>

---
 drivers/gpu/drm/drm_of.c | 70 ++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_of.h     | 10 ++++++
 2 files changed, 80 insertions(+)

drivers/gpu/drm/drm_of.c +46 -0

index 7bbcb999bb75..6c2c97a716fe 100644
@@ -10,6 +10,7 @@
 #include <drm/drm_crtc.h>
 #include <drm/drm_device.h>
 #include <drm/drm_encoder.h>
+#include <drm/drm_mipi_dsi.h>
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 

@@ -493,3 +494,72 @@ int drm_of_get_data_lanes_count_ep(const struct device_node *port,
 	return ret;
 }
 EXPORT_SYMBOL_GPL(drm_of_get_data_lanes_count_ep);
+
+#if IS_ENABLED(CONFIG_DRM_MIPI_DSI)
+
+/**
+ * drm_of_get_dsi_bus - find the DSI bus for a given device
+ * @dev: parent device of display (SPI, I2C)
+ * @info: DSI device info to be updated with DSI node. This is optional
+ * and if not needed can be NULL.
+ *
+ * Gets parent DSI bus for a DSI device controlled through a bus other
+ * than MIPI-DCS (SPI, I2C, etc.) using the Device Tree.
+ *
+ * Returns pointer to mipi_dsi_host if successful, -EINVAL if the
+ * request is unsupported, -EPROBE_DEFER if the DSI host is found but
+ * not available, or -ENODEV otherwise.
+ */
+struct mipi_dsi_host *drm_of_get_dsi_bus(struct device *dev,
+					 struct mipi_dsi_device_info *info)
+{
+	struct mipi_dsi_host *dsi_host;
+	struct device_node *endpoint, *dsi_host_node;
+
+	/*
+	 * Get first endpoint child from device.
+	 */
+	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
+	if (!endpoint)
+		return ERR_PTR(-ENODEV);
+
+	/*
+	 * Follow the first endpoint to get the DSI host node.
+	 */
+	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
+	if (!dsi_host_node)
+		goto error;
+
+	/*
+	 * Get the DSI host from the DSI host node. If we get an error
+	 * or the return is null assume we're not ready to probe just
+	 * yet. Release the DSI host node since we're done with it.
+	 */
+	dsi_host = of_find_mipi_dsi_host_by_node(dsi_host_node);
+	of_node_put(dsi_host_node);
+	if (IS_ERR_OR_NULL(dsi_host)) {
+		of_node_put(endpoint);

drivers/gpu/drm/drm_of.c int drm_of_get_data_lanes_count_ep(const struct device_node *port, · line 551

Quoted 10 lines

drivers/gpu/drm/drm_of.c +10 -0

+		return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	/*
+	 * Set the node of the mipi_dsi_device_info to the correct node
+	 * and then release the endpoint node since we're done with it.
+	 * since this is optional, check if the info is NULL first.
+	 */
+	if (info) {
+		info->node = of_graph_get_remote_port(endpoint);

it looks to me that the info->node is actually the DSI device OF node, not its host port. Which begs the question, why should we even return it there, since there's a pretty big chance that dev->of.node == info->node, and you obviously don't care about the channel and type fields.

I've had a look and node of the current users of mipi_dsi_device_register_full actually register a mipi_dsi_device_info with a node pointer set to !NULL, including the driver in this series.

So, why do we care about the device info at all?

drivers/gpu/drm/drm_of.c int drm_of_get_data_lanes_count_ep(const struct device_node *port, · line 552

Quoted 1 line

drivers/gpu/drm/drm_of.c +1 -0

+		if (IS_ERR_OR_NULL(info->node))

of_graph_get_remote_port doesn't return an error pointer.

Quoted 21 lines

include/drm/drm_of.h +4 -0

@@ -15,6 +15,8 @@ struct drm_encoder;
 struct drm_panel;
 struct drm_bridge;
 struct device_node;
+struct mipi_dsi_device_info;
+struct mipi_dsi_host;
 
 /**
  * enum drm_lvds_dual_link_pixels - Pixel order of an LVDS dual-link connection

@@ -56,6 +58,8 @@ int drm_of_get_data_lanes_count_ep(const struct device_node *port,
 				   int port_reg, int reg,
 				   const unsigned int min,
 				   const unsigned int max);
+struct mipi_dsi_host *drm_of_get_dsi_bus(struct device *dev,
+					 struct mipi_dsi_device_info *info);
 #else
 static inline uint32_t drm_of_crtc_port_mask(struct drm_device *dev,
 					  struct device_node *port)

include/drm/drm_of.h drm_of_get_data_lanes_count_ep(const struct device_node *port, · line 140

Quoted 10 lines

include/drm/drm_of.h +6 -0

@@ -127,6 +131,12 @@ drm_of_get_data_lanes_count_ep(const struct device_node *port,
 {
 	return -EINVAL;
 }
+static inline struct
+mipi_dsi_host *drm_of_get_dsi_bus(struct device *dev,
+					 struct mipi_dsi_device_info *info)
+{
+	return ERR_PTR(-EINVAL);
+}
 #endif

So it looks to me that if CONFIG_OF is defined, we'll define an external symbol declared for drm_of_get_dsi_bus, but that function will only be compiled if CONFIG_DRM_MIPI_DSI is enabled.

What happens if we have CONFIG_OF but not CONFIG_DRM_MIPI_DSI?

If think you need to have here something like:

#ifdef IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_DRM_MIPI_DSI) struct mipi_dsi_host *drm_of_get_dsi_bus(struct device *dev,

       					 struct mipi_dsi_device_info *info);

#else
static inline struct
mipi_dsi_host *drm_of_get_dsi_bus(struct device *dev,
struct mipi_dsi_device_info *info)

{
	return ERR_PTR(-EINVAL);
}

#endif

Maxime

Quoted 93 lines · Maxime Ripard

Hi,

Quoted 74 lines · Chris Morgan

From: Chris Morgan <[email protected]>

Add helper function to find DSI host for devices where DSI panel is not a minor of a DSI bus (such as the Samsung AMS495QA01 panel or the official Raspberry Pi touchscreen display).

Signed-off-by Chris Morgan <[email protected]>

Signed-off-by Maya Matuszczyk <[email protected]>

---
 drivers/gpu/drm/drm_of.c | 70 ++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_of.h     | 10 ++++++
 2 files changed, 80 insertions(+)

drivers/gpu/drm/drm_of.c +46 -0

index 7bbcb999bb75..6c2c97a716fe 100644
@@ -10,6 +10,7 @@
 #include <drm/drm_crtc.h>
 #include <drm/drm_device.h>
 #include <drm/drm_encoder.h>
+#include <drm/drm_mipi_dsi.h>
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 

@@ -493,3 +494,72 @@ int drm_of_get_data_lanes_count_ep(const struct device_node *port,
 	return ret;
 }
 EXPORT_SYMBOL_GPL(drm_of_get_data_lanes_count_ep);
+
+#if IS_ENABLED(CONFIG_DRM_MIPI_DSI)
+
+/**
+ * drm_of_get_dsi_bus - find the DSI bus for a given device
+ * @dev: parent device of display (SPI, I2C)
+ * @info: DSI device info to be updated with DSI node. This is optional
+ * and if not needed can be NULL.
+ *
+ * Gets parent DSI bus for a DSI device controlled through a bus other
+ * than MIPI-DCS (SPI, I2C, etc.) using the Device Tree.
+ *
+ * Returns pointer to mipi_dsi_host if successful, -EINVAL if the
+ * request is unsupported, -EPROBE_DEFER if the DSI host is found but
+ * not available, or -ENODEV otherwise.
+ */
+struct mipi_dsi_host *drm_of_get_dsi_bus(struct device *dev,
+					 struct mipi_dsi_device_info *info)
+{
+	struct mipi_dsi_host *dsi_host;
+	struct device_node *endpoint, *dsi_host_node;
+
+	/*
+	 * Get first endpoint child from device.
+	 */
+	endpoint = of_graph_get_next_endpoint(dev->of_node, NULL);
+	if (!endpoint)
+		return ERR_PTR(-ENODEV);
+
+	/*
+	 * Follow the first endpoint to get the DSI host node.
+	 */
+	dsi_host_node = of_graph_get_remote_port_parent(endpoint);
+	if (!dsi_host_node)
+		goto error;
+
+	/*
+	 * Get the DSI host from the DSI host node. If we get an error
+	 * or the return is null assume we're not ready to probe just
+	 * yet. Release the DSI host node since we're done with it.
+	 */
+	dsi_host = of_find_mipi_dsi_host_by_node(dsi_host_node);
+	of_node_put(dsi_host_node);
+	if (IS_ERR_OR_NULL(dsi_host)) {
+		of_node_put(endpoint);

drivers/gpu/drm/drm_of.c int drm_of_get_data_lanes_count_ep(const struct device_node *port, · line 551

Quoted 10 lines

drivers/gpu/drm/drm_of.c +10 -0

+		return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	/*
+	 * Set the node of the mipi_dsi_device_info to the correct node
+	 * and then release the endpoint node since we're done with it.
+	 * since this is optional, check if the info is NULL first.
+	 */
+	if (info) {
+		info->node = of_graph_get_remote_port(endpoint);

it looks to me that the info->node is actually the DSI device OF node, not its host port. Which begs the question, why should we even return it there, since there's a pretty big chance that dev->of.node == info->node, and you obviously don't care about the channel and type fields.

Quoted 5 lines

I've had a look and node of the current users of mipi_dsi_device_register_full actually register a mipi_dsi_device_info with a node pointer set to !NULL, including the driver in this series.

So, why do we care about the device info at all?

I honestly thought it might be useful, but I can try without it.