support dpms v2

CMakeLists.txt

@@ -147,6 +147,7 @@ add_library(
   src/window.c
   src/dummy_render_surface.c
   src/plugins/services.c
+  src/plugins/dpms_plugin.c
 )
 
 target_link_libraries(flutterpi_module PUBLIC

README.md

@@ -432,6 +432,11 @@ There are several things you need to keep in mind:
         - One of the common reasons is outdated ALSA config in which case you should delete existing config and replace it with up to date one
 - Finally, if you want to verify your audio setup is good, you can use `gst-launch` command to invoke `playbin` on audio file directly.
 
+### Display power management (DPMS)
+
+The `dpms` Dart package can turn the selected KMS display off and back on.
+See [DPMS usage, implementation and hardware checks](docs/DPMS.md).
+
 ## 📊 Performance
 ### Graphics Performance
 Graphics performance is actually pretty good. With most of the apps inside the `flutter SDK -> examples -> catalog` directory I get smooth 50-60fps on the Pi 4 2GB and Pi 3 A+.

src/compositor_ng.c

@@ -581,3 +581,15 @@ void compositor_set_cursor(
 
     compositor_unlock(compositor);
 }
+
+int compositor_get_dpms(struct compositor *compositor) {
+    return window_get_dpms(compositor->main_window);
+}
+
+int compositor_set_dpms(struct compositor *compositor, bool enabled) {
+    return window_set_dpms(compositor->main_window, enabled);
+}
+
+bool compositor_supports_dpms(struct compositor *compositor) {
+    return window_supports_dpms(compositor->main_window);
+}

src/compositor_ng.h

@@ -203,4 +203,9 @@ DECLARE_REF_OPS(fl_layer_composition)
 size_t fl_layer_composition_get_n_layers(struct fl_layer_composition *composition);
 struct fl_layer *fl_layer_composition_peek_layer(struct fl_layer_composition *composition, int layer);
 
+/** DPMS applies to the output selected by the main window. */
+bool compositor_supports_dpms(struct compositor *compositor);
+int compositor_get_dpms(struct compositor *compositor);
+int compositor_set_dpms(struct compositor *compositor, bool enabled);
+
 #endif  // _FLUTTERPI_SRC_COMPOSITOR_NG_H

src/flutter-pi.c

@@ -960,6 +960,11 @@ int flutterpi_respond_to_platform_message(
     return 0;
 }
 
+struct compositor *flutterpi_get_compositor(struct flutterpi *flutterpi) {
+    ASSERT_NOT_NULL(flutterpi);
+    return flutterpi->compositor;
+}
+
 struct texture_registry *flutterpi_get_texture_registry(struct flutterpi *flutterpi) {
     ASSERT_NOT_NULL(flutterpi);
     ASSERT_NOT_NULL(flutterpi->texture_registry);

src/flutter-pi.h

@@ -177,6 +177,8 @@ struct texture_registry *flutterpi_get_texture_registry(struct flutterpi *flutte
 
 struct plugin_registry *flutterpi_get_plugin_registry(struct flutterpi *flutterpi);
 
+struct compositor *flutterpi_get_compositor(struct flutterpi *flutterpi);
+
 FlutterPlatformMessageResponseHandle *
 flutterpi_create_platform_message_response_handle(struct flutterpi *flutterpi, FlutterDataCallback data_callback, void *userdata);
 

src/modesetting.c

@@ -79,6 +79,8 @@ struct kms_req_builder {
     int n_layers;
     struct kms_req_layer layers[32];
 
+    bool is_dpms_req;
+    bool dpms_on;
     bool unset_mode;
     bool has_mode;
     drmModeModeInfo mode;
@@ -425,6 +427,12 @@ static int fetch_crtc(int drm_fd, int crtc_index, uint32_t crtc_id, struct drm_c
     crtc_out->index = crtc_index;
     crtc_out->bitmask = 1u << crtc_index;
     crtc_out->ids = ids;
+    crtc_out->committed_state.active = crtc->mode_valid;
+    for (uint32_t i = 0; i < props->count_props; i++) {
+        if (props->props[i] == ids.active) {
+            crtc_out->committed_state.active = props->prop_values[i] != 0;
+        }
+    }
     crtc_out->committed_state.has_mode = crtc->mode_valid;
     crtc_out->committed_state.mode = crtc->mode;
     crtc_out->committed_state.mode_blob = NULL;
@@ -1237,6 +1245,10 @@ int drmdev_get_event_fd(struct drmdev *drmdev) {
     return drmdev->master_fd;
 }
 
+bool drmdev_supports_dpms(struct drmdev *drmdev, const struct drm_crtc *crtc, const struct drm_connector *connector) {
+    return drmdev->supports_atomic_modesetting ? crtc->ids.active != 0 : connector->ids.dpms != 0;
+}
+
 bool drmdev_supports_dumb_buffers(struct drmdev *drmdev) {
     return drmdev->supports_dumb_buffers;
 }
@@ -2307,6 +2319,7 @@ struct kms_req_builder *drmdev_create_request_builder(struct drmdev *drmdev, uin
 
     if (crtc == NULL) {
         LOG_ERROR("Invalid CRTC id: %" PRId32 "\n", crtc_id);
+        errno = EINVAL;
         goto fail_unlock;
     }
 
@@ -2322,9 +2335,6 @@ struct kms_req_builder *drmdev_create_request_builder(struct drmdev *drmdev, uin
         if (req == NULL) {
             goto fail_free_builder;
         }
-
-        // set the CRTC to active
-        drmModeAtomicAddProperty(req, crtc->id, crtc->ids.active, 1);
     } else {
         req = NULL;
     }
@@ -2356,6 +2366,8 @@ struct kms_req_builder *drmdev_create_request_builder(struct drmdev *drmdev, uin
     builder->n_layers = 0;
     builder->has_mode = false;
     builder->unset_mode = false;
+    builder->is_dpms_req = false;
+    builder->dpms_on = true;
     return builder;
 
 fail_free_builder:
@@ -2366,6 +2378,33 @@ struct kms_req_builder *drmdev_create_request_builder(struct drmdev *drmdev, uin
     return NULL;
 }
 
+struct kms_req *drmdev_create_dpms_req(struct drmdev *drmdev, uint32_t crtc_id, uint32_t connector_id, bool enabled) {
+    struct kms_req_builder *builder;
+    struct kms_req *req;
+    int ok;
+
+    builder = drmdev_create_request_builder(drmdev, crtc_id);
+    if (builder == NULL) {
+        return NULL;
+    }
+
+    ok = kms_req_builder_set_connector(builder, connector_id);
+    if (ok == 0 && (builder->use_legacy ? builder->connector->ids.dpms == 0 : builder->crtc->ids.active == 0)) {
+        ok = ENOTSUP;
+    }
+    if (ok != 0) {
+        kms_req_builder_unref(builder);
+        errno = ok;
+        return NULL;
+    }
+
+    builder->is_dpms_req = true;
+    builder->dpms_on = enabled;
+    req = kms_req_builder_build(builder);
+    kms_req_builder_unref(builder);
+    return req;
+}
+
 static void kms_req_builder_destroy(struct kms_req_builder *builder) {
     /// TODO: Is this complete?
     for (int i = 0; i < builder->n_layers; i++) {
@@ -2804,10 +2843,6 @@ kms_req_commit_locked(struct kms_req *req, bool blocking, kms_scanout_cb_t scano
     ASSERT_NOT_NULL(req);
     builder = (struct kms_req_builder *) req;
 
-    if (builder->drmdev->per_crtc_state[builder->crtc->index].flip_pending) {
-        return EBUSY;
-    }
-
     if (builder->drmdev->master_fd < 0) {
         LOG_ERROR("Commit requested, but drmdev doesn't have a DRM master fd right now.\n");
         ok = EBUSY;
@@ -2820,6 +2855,55 @@ kms_req_commit_locked(struct kms_req *req, bool blocking, kms_scanout_cb_t scano
         goto fail_unlock;
     }
 
+    if (builder->is_dpms_req && !blocking) {
+        return ENOTSUP;
+    }
+
+    if (blocking) {
+        // A blocking update supersedes the queued frame. Drop it before
+        // draining so the flip handler cannot submit it and enable the CRTC
+        // after a power change.
+        kms_req_swap_ptrs(&builder->drmdev->per_crtc_state[builder->crtc->index].queued, NULL);
+        while (builder->drmdev->per_crtc_state[builder->crtc->index].flip_pending) {
+            ok = drmdev_on_modesetting_fd_ready_locked(builder->drmdev);
+            if (ok != 0) {
+                LOG_ERROR("Could not drain page flips before blocking commit.\n");
+                goto fail_unlock;
+            }
+        }
+    } else if (builder->drmdev->per_crtc_state[builder->crtc->index].flip_pending) {
+        return EBUSY;
+    }
+
+    if (builder->is_dpms_req) {
+        // A disabled CRTC produces no page-flip event. Do not enter the normal
+        // scanout path or replace last_flipped: its buffers remain attached.
+        if (builder->use_legacy) {
+            ok = drmModeConnectorSetProperty(
+                builder->drmdev->master_fd,
+                builder->connector->id,
+                builder->connector->ids.dpms,
+                builder->dpms_on ? DRM_MODE_DPMS_ON : DRM_MODE_DPMS_OFF
+            );
+        } else {
+            ok = drmModeAtomicAddProperty(builder->req, builder->crtc->id, builder->crtc->ids.active, builder->dpms_on);
+            if (ok < 0) {
+                ok = -ok;
+                goto fail_unlock;
+            }
+            ok = drmModeAtomicCommit(builder->drmdev->master_fd, builder->req, DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
+        }
+        if (ok != 0) {
+            ok = errno;
+            goto fail_unlock;
+        }
+        builder->crtc->committed_state.active = builder->dpms_on;
+        if (scanout_cb != NULL) {
+            scanout_cb(builder->drmdev, 0, userdata);
+        }
+        return 0;
+    }
+
     // only change the mode if the new mode differs from the old one
 
     /// TOOD: If this is not a standard mode reported by connector/CRTC,
@@ -2852,6 +2936,18 @@ kms_req_commit_locked(struct kms_req *req, bool blocking, kms_scanout_cb_t scano
     }
 
     if (builder->use_legacy) {
+        if (!builder->crtc->committed_state.active && builder->connector != NULL && builder->connector->ids.dpms != 0) {
+            ok = drmModeConnectorSetProperty(
+                builder->drmdev->master_fd,
+                builder->connector->id,
+                builder->connector->ids.dpms,
+                DRM_MODE_DPMS_ON
+            );
+            if (ok != 0) {
+                ok = errno;
+                goto fail_maybe_destroy_mode_blob;
+            }
+        }
         ASSERT_EQUALS(builder->layers[0].layer.dst_x, 0);
         ASSERT_EQUALS(builder->layers[0].layer.dst_y, 0);
         ASSERT_EQUALS(builder->layers[0].layer.dst_w, builder->mode.hdisplay);
@@ -2951,9 +3047,17 @@ kms_req_commit_locked(struct kms_req *req, bool blocking, kms_scanout_cb_t scano
         /// TODO: Call drmModeSetPlane for all other layers
         /// TODO: Assert here
     } else {
+        // Every frame request implicitly enables the display. Power-only
+        // requests take the separate path above and never add framebuffer layers.
+        ok = drmModeAtomicAddProperty(builder->req, builder->crtc->id, builder->crtc->ids.active, !builder->unset_mode);
+        if (ok < 0) {
+            ok = -ok;
+            goto fail_maybe_destroy_mode_blob;
+        }
         /// TODO: If we can do explicit fencing, don't use the page flip event.
         /// TODO: Can we set OUT_FENCE_PTR even though we didn't set any IN_FENCE_FDs?
-        flags = DRM_MODE_PAGE_FLIP_EVENT | (blocking ? 0 : DRM_MODE_ATOMIC_NONBLOCK) | (update_mode ? DRM_MODE_ATOMIC_ALLOW_MODESET : 0);
+        flags = DRM_MODE_PAGE_FLIP_EVENT | (blocking ? 0 : DRM_MODE_ATOMIC_NONBLOCK) |
+                ((update_mode || !builder->crtc->committed_state.active) ? DRM_MODE_ATOMIC_ALLOW_MODESET : 0);
 
         // All planes that are not used by us and are connected to our CRTC
         // should be disabled.
@@ -3024,6 +3128,7 @@ kms_req_commit_locked(struct kms_req *req, bool blocking, kms_scanout_cb_t scano
     }
 
     // update struct drm_crtc.committed_state
+    builder->crtc->committed_state.active = !builder->unset_mode;
     if (update_mode) {
         // destroy the old mode blob
         if (builder->crtc->committed_state.mode_blob != NULL) {

src/modesetting.h

@@ -394,6 +394,7 @@ struct drm_crtc {
     struct drm_crtc_prop_ids ids;
 
     struct {
+        bool active;
         bool has_mode;
         drmModeModeInfo mode;
         struct drm_mode_blob *mode_blob;
@@ -635,6 +636,7 @@ struct _drmModeModeInfo;
 int drmdev_get_fd(struct drmdev *drmdev);
 int drmdev_get_event_fd(struct drmdev *drmdev);
 bool drmdev_supports_dumb_buffers(struct drmdev *drmdev);
+bool drmdev_supports_dpms(struct drmdev *drmdev, const struct drm_crtc *crtc, const struct drm_connector *connector);
 int drmdev_create_dumb_buffer(
     struct drmdev *drmdev,
     int width,
@@ -752,6 +754,13 @@ struct kms_req_builder;
 
 struct kms_req_builder *drmdev_create_request_builder(struct drmdev *drmdev, uint32_t crtc_id);
 
+/**
+ * Create a power-only request for the selected output. Keeps its mode, planes and
+ * framebuffer references intact. Commit with kms_req_commit_blocking; there is
+ * no page-flip event and its returned vblank timestamp is zero.
+ */
+struct kms_req *drmdev_create_dpms_req(struct drmdev *drmdev, uint32_t crtc_id, uint32_t connector_id, bool enabled);
+
 DECLARE_REF_OPS(kms_req_builder);
 
 /**
@@ -901,8 +910,8 @@ int kms_req_builder_push_zpos_placeholder_layer(struct kms_req_builder *builder,
  * @brief A KMS request (atomic or legacy modesetting) that can be committed to
  * change the state of a single CRTC.
  *
- * Only way to construct this is by building a KMS request using
- * @ref kms_req_builder and then calling @ref kms_req_builder_build.
+ * Construct a frame request using @ref kms_req_builder_build, or a power-only
+ * request using @ref drmdev_create_dpms_req.
  */
 struct kms_req;
 
@@ -920,6 +929,11 @@ DECLARE_REF_OPS(kms_req);
  */
 struct kms_req *kms_req_builder_build(struct kms_req_builder *builder);
 
+/**
+ * Discard the queued frame for this CRTC and wait for its outstanding flip
+ * before committing the request. Frame requests also wait for their own flip;
+ * power-only requests produce no flip and return a zero vblank timestamp.
+ */
 int kms_req_commit_blocking(struct kms_req *req, uint64_t *vblank_ns_out);
 
 int kms_req_commit_nonblocking(struct kms_req *req, kms_scanout_cb_t scanout_cb, void *userdata, void_callback_t destroy_cb);

src/plugins/dpms_plugin.c

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT
+#include "plugins/dpms_plugin.h"
+
+#include <errno.h>
+
+#include "compositor_ng.h"
+#include "flutter-pi.h"
+
+int32_t flutterpi_dpms_is_available(void) {
+    return flutterpi != NULL && compositor_supports_dpms(flutterpi_get_compositor(flutterpi));
+}
+
+int32_t flutterpi_dpms_get(void) {
+    if (flutterpi == NULL) {
+        return -ENODEV;
+    }
+    return compositor_get_dpms(flutterpi_get_compositor(flutterpi));
+}
+
+int32_t flutterpi_dpms_set(bool enabled) {
+    if (flutterpi == NULL) {
+        return ENODEV;
+    }
+    return compositor_set_dpms(flutterpi_get_compositor(flutterpi), enabled);
+}

src/plugins/dpms_plugin.h

@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: MIT
+#ifndef _FLUTTERPI_PLUGINS_DPMS_PLUGIN_H
+#define _FLUTTERPI_PLUGINS_DPMS_PLUGIN_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/** FFI ABI: 0 unavailable, 1 available. */
+int32_t flutterpi_dpms_is_available(void);
+
+/** FFI ABI: 0 off, 1 on, negative errno on error. */
+int32_t flutterpi_dpms_get(void);
+
+/** FFI ABI: 0 success, positive errno on error. May block for a modeset. */
+int32_t flutterpi_dpms_set(bool enabled);
+
+#endif  // _FLUTTERPI_PLUGINS_DPMS_PLUGIN_H