Re: [PATCH v2] drm/amd/display: add panel_power_savings sysfs entry to eDP connectors

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Am 02.02.24 um 16:28 schrieb Hamza Mahfooz:
We want programs besides the compositor to be able to enable or disable
panel power saving features.

Well I don't know the full background, but that is usually a no-go.

However, since they are currently only
configurable through DRM properties, that isn't possible.

Maybe I'm repeating others, but I wanted to point it out explicitly: This is intentional and not that easily changeable.

If it's a common DRM property, e.g. something standardized among all drivers, then amdgpu is not allowed to circumvent that.

Regards,
Christian.

  So, to remedy
that issue introduce a new "panel_power_savings" sysfs attribute.

Cc: Mario Limonciello <mario.limonciello@xxxxxxx>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
---
v2: hide ABM_LEVEL_IMMEDIATE_DISABLE in the read case, force an atomic
     commit when setting the value, call sysfs_remove_group() in
     amdgpu_dm_connector_unregister() and add some documentation.
---
  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 76 +++++++++++++++++++
  1 file changed, 76 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 8590c9f1dda6..3c62489d03dc 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6436,10 +6436,79 @@ 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);
+ sysfs_remove_group(&connector->kdev->kobj, &amdgpu_group);
  	drm_dp_aux_unregister(&amdgpu_dm_connector->dm_dp_aux.aux);
  }
@@ -6541,6 +6610,13 @@ 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) ||




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