drm/amd/display: multi-eDP backlight support

[why]
Currently the assumption is that we are using a single eDP
connector so there will only be one backlight object. Need changes
to allow brightness update and reading for multiple eDP connectors.

[how]
- register a single device
- turn backlight link from a pointer to an array of pointers
- update brightness of all eDP links at the same time when request
is registered
- read brightness level only of the primary eDP panel
- turn current_backlight_pwm and targer_backlight_pwm debugfs enteries
into per connector enteries.
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Wayne Lin <waynelin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -3415,22 +3415,37 @@ static int amdgpu_dm_backlight_update_status(struct backlight_device *bd)
 {
 	struct amdgpu_display_manager *dm = bl_get_data(bd);
 	struct amdgpu_dm_backlight_caps caps;
-	struct dc_link *link = NULL;
+	struct dc_link *link[AMDGPU_DM_MAX_NUM_EDP];
 	u32 brightness;
 	bool rc;
+	int i;
 
 	amdgpu_dm_update_backlight_caps(dm);
 	caps = dm->backlight_caps;
 
-	link = (struct dc_link *)dm->backlight_link;
+	for (i = 0; i < dm->num_of_edps; i++)
+		link[i] = (struct dc_link *)dm->backlight_link[i];
 
 	brightness = convert_brightness_from_user(&caps, bd->props.brightness);
 	// Change brightness based on AUX property
-	if (caps.aux_support)
-		rc = dc_link_set_backlight_level_nits(link, true, brightness,
-						      AUX_BL_DEFAULT_TRANSITION_TIME_MS);
-	else
-		rc = dc_link_set_backlight_level(dm->backlight_link, brightness, 0);
+	if (caps.aux_support) {
+		for (i = 0; i < dm->num_of_edps; i++) {
+			rc = dc_link_set_backlight_level_nits(link[i], true, brightness,
+				AUX_BL_DEFAULT_TRANSITION_TIME_MS);
+			if (!rc) {
+				DRM_ERROR("DM: Failed to update backlight via AUX on eDP[%d]\n", i);
+				break;
+			}
+		}
+	} else {
+		for (i = 0; i < dm->num_of_edps; i++) {
+			rc = dc_link_set_backlight_level(dm->backlight_link[i], brightness, 0);
+			if (!rc) {
+				DRM_ERROR("DM: Failed to update backlight on eDP[%d]\n", i);
+				break;
+			}
+		}
+	}
 
 	return rc ? 0 : 1;
 }
@@ -3444,7 +3459,7 @@ static int amdgpu_dm_backlight_get_brightness(struct backlight_device *bd)
 	caps = dm->backlight_caps;
 
 	if (caps.aux_support) {
-		struct dc_link *link = (struct dc_link *)dm->backlight_link;
+		struct dc_link *link = (struct dc_link *)dm->backlight_link[0];
 		u32 avg, peak;
 		bool rc;
 
@@ -3453,7 +3468,7 @@ static int amdgpu_dm_backlight_get_brightness(struct backlight_device *bd)
 			return bd->props.brightness;
 		return convert_brightness_to_user(&caps, avg);
 	} else {
-		int ret = dc_link_get_backlight_level(dm->backlight_link);
+		int ret = dc_link_get_backlight_level(dm->backlight_link[0]);
 
 		if (ret == DC_ERROR_UNEXPECTED)
 			return bd->props.brightness;
@@ -3550,10 +3565,13 @@ static void register_backlight_device(struct amdgpu_display_manager *dm,
 		 * DM initialization because not having a backlight control
 		 * is better then a black screen.
 		 */
-		amdgpu_dm_register_backlight_device(dm);
+		if (!dm->backlight_dev)
+			amdgpu_dm_register_backlight_device(dm);
 
-		if (dm->backlight_dev)
-			dm->backlight_link = link;
+		if (dm->backlight_dev) {
+			dm->backlight_link[dm->num_of_edps] = link;
+			dm->num_of_edps++;
+		}
 	}
 #endif
 }

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

@@ -46,6 +46,7 @@
 
 #define AMDGPU_DM_MAX_CRTC 6
 
+#define AMDGPU_DM_MAX_NUM_EDP 2
 /*
 #include "include/amdgpu_dal_power_if.h"
 #include "amdgpu_dm_irq.h"
@@ -354,7 +355,10 @@ struct amdgpu_display_manager {
 
 	struct backlight_device *backlight_dev;
 
-	const struct dc_link *backlight_link;
+	const struct dc_link *backlight_link[AMDGPU_DM_MAX_NUM_EDP];
+
+	uint8_t num_of_edps;
+
 	struct amdgpu_dm_backlight_caps backlight_caps;
 
 	struct mod_freesync *freesync_module;

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c

@@ -2377,6 +2377,44 @@ static ssize_t dp_max_bpc_write(struct file *f, const char __user *buf,
 	return size;
 }
 
+/*
+ * Backlight at this moment.  Read only.
+ * As written to display, taking ABM and backlight lut into account.
+ * Ranges from 0x0 to 0x10000 (= 100% PWM)
+ *
+ * Example usage: cat /sys/kernel/debug/dri/0/eDP-1/current_backlight
+ */
+static int current_backlight_show(struct seq_file *m, void *unused)
+{
+	struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(m->private);
+	struct dc_link *link = aconnector->dc_link;
+	unsigned int backlight;
+
+	backlight = dc_link_get_backlight_level(link);
+	seq_printf(m, "0x%x\n", backlight);
+
+	return 0;
+}
+
+/*
+ * Backlight value that is being approached.  Read only.
+ * As written to display, taking ABM and backlight lut into account.
+ * Ranges from 0x0 to 0x10000 (= 100% PWM)
+ *
+ * Example usage: cat /sys/kernel/debug/dri/0/eDP-1/target_backlight
+ */
+static int target_backlight_show(struct seq_file *m, void *unused)
+{
+	struct amdgpu_dm_connector *aconnector = to_amdgpu_dm_connector(m->private);
+	struct dc_link *link = aconnector->dc_link;
+	unsigned int backlight;
+
+	backlight = dc_link_get_target_backlight_pwm(link);
+	seq_printf(m, "0x%x\n", backlight);
+
+	return 0;
+}
+
 DEFINE_SHOW_ATTRIBUTE(dp_dsc_fec_support);
 DEFINE_SHOW_ATTRIBUTE(dmub_fw_state);
 DEFINE_SHOW_ATTRIBUTE(dmub_tracebuffer);
@@ -2611,6 +2649,9 @@ DEFINE_DEBUGFS_ATTRIBUTE(dmcub_trace_event_state_fops, dmcub_trace_event_state_g
 
 DEFINE_DEBUGFS_ATTRIBUTE(psr_fops, psr_get, NULL, "%llu\n");
 
+DEFINE_SHOW_ATTRIBUTE(current_backlight);
+DEFINE_SHOW_ATTRIBUTE(target_backlight);
+
 static const struct {
 	char *name;
 	const struct file_operations *fops;
@@ -2634,8 +2675,13 @@ void connector_debugfs_init(struct amdgpu_dm_connector *connector)
 					    dp_debugfs_entries[i].fops);
 		}
 	}
-	if (connector->base.connector_type == DRM_MODE_CONNECTOR_eDP)
+	if (connector->base.connector_type == DRM_MODE_CONNECTOR_eDP) {
 		debugfs_create_file_unsafe("psr_state", 0444, dir, connector, &psr_fops);
+		debugfs_create_file("amdgpu_current_backlight_pwm", 0444, dir, connector,
+				    &current_backlight_fops);
+		debugfs_create_file("amdgpu_target_backlight_pwm", 0444, dir, connector,
+				    &target_backlight_fops);
+	}
 
 	for (i = 0; i < ARRAY_SIZE(connector_debugfs_entries); i++) {
 		debugfs_create_file(connector_debugfs_entries[i].name,
@@ -2938,38 +2984,6 @@ static ssize_t dtn_log_write(
 	return size;
 }
 
-/*
- * Backlight at this moment.  Read only.
- * As written to display, taking ABM and backlight lut into account.
- * Ranges from 0x0 to 0x10000 (= 100% PWM)
- */
-static int current_backlight_show(struct seq_file *m, void *unused)
-{
-	struct amdgpu_device *adev = (struct amdgpu_device *)m->private;
-	struct amdgpu_display_manager *dm = &adev->dm;
-
-	unsigned int backlight = dc_link_get_backlight_level(dm->backlight_link);
-
-	seq_printf(m, "0x%x\n", backlight);
-	return 0;
-}
-
-/*
- * Backlight value that is being approached.  Read only.
- * As written to display, taking ABM and backlight lut into account.
- * Ranges from 0x0 to 0x10000 (= 100% PWM)
- */
-static int target_backlight_show(struct seq_file *m, void *unused)
-{
-	struct amdgpu_device *adev = (struct amdgpu_device *)m->private;
-	struct amdgpu_display_manager *dm = &adev->dm;
-
-	unsigned int backlight = dc_link_get_target_backlight_pwm(dm->backlight_link);
-
-	seq_printf(m, "0x%x\n", backlight);
-	return 0;
-}
-
 static int mst_topo_show(struct seq_file *m, void *unused)
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)m->private;
@@ -3152,8 +3166,6 @@ static int visual_confirm_get(void *data, u64 *val)
 	return 0;
 }
 
-DEFINE_SHOW_ATTRIBUTE(current_backlight);
-DEFINE_SHOW_ATTRIBUTE(target_backlight);
 DEFINE_SHOW_ATTRIBUTE(mst_topo);
 DEFINE_DEBUGFS_ATTRIBUTE(visual_confirm_fops, visual_confirm_get,
 			 visual_confirm_set, "%llu\n");
@@ -3233,10 +3245,6 @@ void dtn_debugfs_init(struct amdgpu_device *adev)
 	struct drm_minor *minor = adev_to_drm(adev)->primary;
 	struct dentry *root = minor->debugfs_root;
 
-	debugfs_create_file("amdgpu_current_backlight_pwm", 0444,
-			    root, adev, &current_backlight_fops);
-	debugfs_create_file("amdgpu_target_backlight_pwm", 0444,
-			    root, adev, &target_backlight_fops);
 	debugfs_create_file("amdgpu_mst_topology", 0444, root,
 			    adev, &mst_topo_fops);
 	debugfs_create_file("amdgpu_dm_dtn_log", 0644, root, adev,