Add force-disable-connectors-on-resume debug flag

docs/wiki/Configuration:-Debug-Options.md

@@ -17,6 +17,7 @@ debug {
     disable-cursor-plane
     disable-direct-scanout
     restrict-primary-scanout-to-matching-format
+    force-disable-connectors-on-resume
     render-drm-device "/dev/dri/renderD129"
     ignore-drm-device "/dev/dri/renderD128"
     ignore-drm-device "/dev/dri/renderD130"
@@ -104,6 +105,19 @@ debug {
 }
 ```
 
+### `force-disable-connectors-on-resume`
+
+Force-disables all outputs upon resuming niri (TTY switch or waking up from suspend).
+This causes a modeset/screen blank on all outputs.
+
+If niri rendering is corrupted, or monitors don't light up after a TTY switch, you can try this flag.
+
+```kdl
+debug {
+    force-disable-connectors-on-resume
+}
+```
+
 ### `render-drm-device`
 
 Override the DRM device that niri will use for all rendering.

niri-config/src/debug.rs

@@ -12,6 +12,7 @@ pub struct Debug {
     pub disable_direct_scanout: bool,
     pub keep_max_bpc_unchanged: bool,
     pub restrict_primary_scanout_to_matching_format: bool,
+    pub force_disable_connectors_on_resume: bool,
     pub render_drm_device: Option<PathBuf>,
     pub ignored_drm_devices: Vec<PathBuf>,
     pub force_pipewire_invalid_modifier: bool,
@@ -44,6 +45,8 @@ pub struct DebugPart {
     pub keep_max_bpc_unchanged: Option<Flag>,
     #[knuffel(child)]
     pub restrict_primary_scanout_to_matching_format: Option<Flag>,
+    #[knuffel(child)]
+    pub force_disable_connectors_on_resume: Option<Flag>,
     #[knuffel(child, unwrap(argument))]
     pub render_drm_device: Option<PathBuf>,
     #[knuffel(children(name = "ignore-drm-device"), unwrap(argument))]
@@ -81,6 +84,7 @@ impl MergeWith<DebugPart> for Debug {
             disable_direct_scanout,
             keep_max_bpc_unchanged,
             restrict_primary_scanout_to_matching_format,
+            force_disable_connectors_on_resume,
             force_pipewire_invalid_modifier,
             emulate_zero_presentation_time,
             disable_resize_throttling,

niri-config/src/lib.rs

@@ -2134,6 +2134,7 @@ mod tests {
                 disable_direct_scanout: false,
                 keep_max_bpc_unchanged: false,
                 restrict_primary_scanout_to_matching_format: false,
+                force_disable_connectors_on_resume: false,
                 render_drm_device: Some(
                     "/dev/dri/renderD129",
                 ),

src/backend/tty.rs

@@ -646,7 +646,16 @@ impl Tty {
 
                     // It hasn't been removed, update its state as usual.
                     let device = self.devices.get_mut(&node).unwrap();
-                    if let Err(err) = device.drm.activate(false) {
+
+                    // Someone on an old device hit what seems to be a driver bug without this:
+                    // https://github.com/YaLTeR/niri/issues/3048
+                    let force_disable = self
+                        .config
+                        .borrow()
+                        .debug
+                        .force_disable_connectors_on_resume;
+
+                    if let Err(err) = device.drm.activate(force_disable) {
                         warn!("error activating DRM device: {err:?}");
                     }
                     if let Some(lease_state) = &mut device.drm_lease_state {
@@ -1055,6 +1064,7 @@ impl Tty {
                 if let Err(err) = surface.compositor.reset_state() {
                     warn!("error resetting DrmCompositor state: {err:?}");
                 }
+                surface.compositor.reset_buffers();
             }
         }