drm: Introduce 'power saving policy' drm property

The `power saving policy` DRM property is an optional property that
can be added to a connector by a driver.

This property is for compositors to indicate intent of policy of
whether a driver can use power saving features that may compromise
the experience intended by the compositor.

Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240703051722.328-2-mario.limonciello@amd.com

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index b4f4d2f908d157a57e5dbb97e83e0c14086413ac..7c44e3a1d8e05e3d2bbede271304a1300039cce7 100644 (file)
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1043,6 +1043,11 @@ static const struct drm_prop_enum_list drm_scaling_mode_enum_list[] = {
        { DRM_MODE_SCALE_ASPECT, "Full aspect" },
 };
 
+static const struct drm_prop_enum_list drm_power_saving_policy_enum_list[] = {
+       { __builtin_ffs(DRM_MODE_REQUIRE_COLOR_ACCURACY) - 1, "Require color accuracy" },
+       { __builtin_ffs(DRM_MODE_REQUIRE_LOW_LATENCY) - 1, "Require low latency" },
+};
+
 static const struct drm_prop_enum_list drm_aspect_ratio_enum_list[] = {
        { DRM_MODE_PICTURE_ASPECT_NONE, "Automatic" },
        { DRM_MODE_PICTURE_ASPECT_4_3, "4:3" },
@@ -1629,6 +1634,16 @@ EXPORT_SYMBOL(drm_hdmi_connector_get_output_format_name);
  *
  *     Drivers can set up these properties by calling
  *     drm_mode_create_tv_margin_properties().
+ * power saving policy:
+ *     This property is used to set the power saving policy for the connector.
+ *     This property is populated with a bitmask of optional requirements set
+ *     by the drm master for the drm driver to respect:
+ *     - "Require color accuracy": Disable power saving features that will
+ *       affect color fidelity.
+ *       For example: Hardware assisted backlight modulation.
+ *     - "Require low latency": Disable power saving features that will
+ *       affect latency.
+ *       For example: Panel self refresh (PSR)
  */
 
 int drm_connector_create_standard_properties(struct drm_device *dev)
@@ -2131,6 +2146,39 @@ int drm_mode_create_scaling_mode_property(struct drm_device *dev)
 }
 EXPORT_SYMBOL(drm_mode_create_scaling_mode_property);
 
+/**
+ * drm_mode_create_power_saving_policy_property - create power saving policy property
+ * @dev: DRM device
+ * @supported_policies: bitmask of supported power saving policies
+ *
+ * Called by a driver the first time it's needed, must be attached to desired
+ * connectors.
+ *
+ * Returns: %0
+ */
+int drm_mode_create_power_saving_policy_property(struct drm_device *dev,
+                                                uint64_t supported_policies)
+{
+       struct drm_property *power_saving;
+
+       if (dev->mode_config.power_saving_policy)
+               return 0;
+       WARN_ON((supported_policies & DRM_MODE_POWER_SAVING_POLICY_ALL) == 0);
+
+       power_saving =
+               drm_property_create_bitmask(dev, 0, "power saving policy",
+                                           drm_power_saving_policy_enum_list,
+                                           ARRAY_SIZE(drm_power_saving_policy_enum_list),
+                                           supported_policies);
+       if (!power_saving)
+               return -ENOMEM;
+
+       dev->mode_config.power_saving_policy = power_saving;
+
+       return 0;
+}
+EXPORT_SYMBOL(drm_mode_create_power_saving_policy_property);
+
 /**
  * DOC: Variable refresh properties
  *

diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index e3fa43291f449d70f3b92a00985336c4f2237bc6..5ad7352534136cadda4cbcae6c90e22b054e3716 100644 (file)
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -2267,6 +2267,8 @@ int drm_mode_create_dp_colorspace_property(struct drm_connector *connector,
                                           u32 supported_colorspaces);
 int drm_mode_create_content_type_property(struct drm_device *dev);
 int drm_mode_create_suggested_offset_properties(struct drm_device *dev);
+int drm_mode_create_power_saving_policy_property(struct drm_device *dev,
+                                                uint64_t supported_policies);
 
 int drm_connector_set_path_property(struct drm_connector *connector,
                                    const char *path);

diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
index ab0f167474b1f1a85e46bd83b6d0c6cbfa22dc1b..150f9a3b649f4ec1d68ccd9926b576a1805dce94 100644 (file)
--- a/include/drm/drm_mode_config.h
+++ b/include/drm/drm_mode_config.h
@@ -969,6 +969,11 @@ struct drm_mode_config {
         */
        struct drm_atomic_state *suspend_state;
 
+       /**
+        * @power_saving_policy: bitmask for power saving policy requests.
+        */
+       struct drm_property *power_saving_policy;
+
        const struct drm_mode_config_helper_funcs *helper_private;
 };
 

diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index d390011b89b49546bd4ebf47b71567cb1bc958ce..880303c2ad97e9b17ab7ad38d8261df6d17221bc 100644 (file)
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -152,6 +152,13 @@ extern "C" {
 #define DRM_MODE_SCALE_CENTER          2 /* Centered, no scaling */
 #define DRM_MODE_SCALE_ASPECT          3 /* Full screen, preserve aspect */
 
+/* power saving policy options */
+#define DRM_MODE_REQUIRE_COLOR_ACCURACY        BIT(0)  /* Compositor requires color accuracy */
+#define DRM_MODE_REQUIRE_LOW_LATENCY   BIT(1)  /* Compositor requires low latency */
+
+#define DRM_MODE_POWER_SAVING_POLICY_ALL       (DRM_MODE_REQUIRE_COLOR_ACCURACY |\
+                                                DRM_MODE_REQUIRE_LOW_LATENCY)
+
 /* Dithering mode options */
 #define DRM_MODE_DITHERING_OFF 0
 #define DRM_MODE_DITHERING_ON  1