[PATCH 1/2][Noble] drm/amd/display: add panel_power_savings sysfs entry to eDP connectors

[You-Sheng Yang]

From: Hamza Mahfooz <hamza.mahfooz at amd.com>

BugLink: https://bugs.launchpad.net/bugs/2056716

We want programs besides the compositor to be able to enable or disable
panel power saving features. However, since they are currently only
configurable through DRM properties, that isn't possible. So, to remedy
that issue introduce a new "panel_power_savings" sysfs attribute.

v2: squash in fix from Hamza (Alex)

Cc: Mario Limonciello <mario.limonciello at amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello at amd.com>
Tested-by: Mario Limonciello <mario.limonciello at amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
(cherry picked from commit 63d0b87213a0ba241b3fcfba3fe7b0aed0cd1cc5 linux-next)
Signed-off-by: You-Sheng Yang <vicamo.yang at canonical.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 78 +++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 5853cf022917..088356d9b924 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6409,10 +6409,81 @@ int amdgpu_dm_connector_atomic_get_property(struct drm_connector *connector,
 	return ret;
 }
 
+/**
+ * DOC: panel power savings
+ *
+ * The display manager allows you to set your desired **panel power savings**
+ * level (between 0-4, with 0 representing off), e.g. using the following::
+ *
+ *   # echo 3 > /sys/class/drm/card0-eDP-1/amdgpu/panel_power_savings
+ *
+ * Modifying this value can have implications on color accuracy, so tread
+ * carefully.
+ */
+
+static ssize_t panel_power_savings_show(struct device *device,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct drm_connector *connector = dev_get_drvdata(device);
+	struct drm_device *dev = connector->dev;
+	u8 val;
+
+	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
+	val = to_dm_connector_state(connector->state)->abm_level ==
+		ABM_LEVEL_IMMEDIATE_DISABLE ? 0 :
+		to_dm_connector_state(connector->state)->abm_level;
+	drm_modeset_unlock(&dev->mode_config.connection_mutex);
+
+	return sysfs_emit(buf, "%u\n", val);
+}
+
+static ssize_t panel_power_savings_store(struct device *device,
+					 struct device_attribute *attr,
+					 const char *buf, size_t count)
+{
+	struct drm_connector *connector = dev_get_drvdata(device);
+	struct drm_device *dev = connector->dev;
+	long val;
+	int ret;
+
+	ret = kstrtol(buf, 0, &val);
+
+	if (ret)
+		return ret;
+
+	if (val < 0 || val > 4)
+		return -EINVAL;
+
+	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
+	to_dm_connector_state(connector->state)->abm_level = val ?:
+		ABM_LEVEL_IMMEDIATE_DISABLE;
+	drm_modeset_unlock(&dev->mode_config.connection_mutex);
+
+	drm_kms_helper_hotplug_event(dev);
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(panel_power_savings);
+
+static struct attribute *amdgpu_attrs[] = {
+	&dev_attr_panel_power_savings.attr,
+	NULL
+};
+
+static const struct attribute_group amdgpu_group = {
+	.name = "amdgpu",
+	.attrs = amdgpu_attrs
+};
+
 static void amdgpu_dm_connector_unregister(struct drm_connector *connector)
 {
 	struct amdgpu_dm_connector *amdgpu_dm_connector = to_amdgpu_dm_connector(connector);
 
+	if (connector->connector_type == DRM_MODE_CONNECTOR_eDP)
+		sysfs_remove_group(&connector->kdev->kobj, &amdgpu_group);
+
 	drm_dp_aux_unregister(&amdgpu_dm_connector->dm_dp_aux.aux);
 }
 
@@ -6514,6 +6585,13 @@ amdgpu_dm_connector_late_register(struct drm_connector *connector)
 		to_amdgpu_dm_connector(connector);
 	int r;
 
+	if (connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
+		r = sysfs_create_group(&connector->kdev->kobj,
+				       &amdgpu_group);
+		if (r)
+			return r;
+	}
+
 	amdgpu_dm_register_backlight_device(amdgpu_dm_connector);
 
 	if ((connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) ||
-- 
2.43.0