metal: allow changing the connector mode

jay-config/src/_private/client.rs

@@ -570,6 +570,10 @@ impl Client {
         }
     }
 
+    pub fn connector_set_mode(&self, connector: Connector, mode: WireMode) {
+        self.send(&ClientMessage::ConnectorSetMode { connector, mode });
+    }
+
     pub fn connector_modes(&self, connector: Connector) -> Vec<Mode> {
         let res = self.send_with_response(&ClientMessage::ConnectorModes { connector });
         get_response!(res, Vec::new(), ConnectorModes { modes });

jay-config/src/_private/ipc.rs

@@ -356,6 +356,10 @@ pub enum ClientMessage<'a> {
     ConnectorModes {
         connector: Connector,
     },
+    ConnectorSetMode {
+        connector: Connector,
+        mode: WireMode,
+    },
 }
 
 #[derive(Serialize, Deserialize, Debug)]

jay-config/src/video.rs

@@ -9,6 +9,7 @@ use {
             CON_VIRTUAL, CON_WRITEBACK,
         },
         PciId,
+        _private::WireMode,
     },
     serde::{Deserialize, Serialize},
     std::str::FromStr,
@@ -112,6 +113,42 @@ impl Connector {
         get!(Mode::zeroed()).connector_mode(self)
     }
 
+    /// Tries to set the mode of the connector.
+    ///
+    /// If the refresh rate is not specified, tries to use the first mode with the given
+    /// width and height.
+    ///
+    /// The default mode is the first mode advertised by the connector. This is usually
+    /// the native mode.
+    pub fn set_mode(self, width: i32, height: i32, refresh_millihz: Option<u32>) {
+        if !self.exists() {
+            log::warn!("set_mode called on a connector that does not exist");
+            return;
+        }
+        let refresh_millihz = match refresh_millihz {
+            Some(r) => r,
+            _ => match self
+                .modes()
+                .iter()
+                .find(|m| m.width == width && m.height == height)
+            {
+                Some(m) => m.refresh_millihz,
+                _ => {
+                    log::warn!("Could not find any mode with width {width} and height {height}");
+                    return;
+                }
+            },
+        };
+        get!().connector_set_mode(
+            self,
+            WireMode {
+                width,
+                height,
+                refresh_millihz,
+            },
+        )
+    }
+
     /// Returns the available modes of the connector.
     pub fn modes(self) -> Vec<Mode> {
         if !self.exists() {

src/backend.rs

@@ -83,6 +83,7 @@ pub trait Connector {
     fn drm_feedback(&self) -> Option<Rc<DrmFeedback>> {
         None
     }
+    fn set_mode(&self, mode: Mode);
 }
 
 #[derive(Debug)]

src/backends/dummy.rs

@@ -2,7 +2,7 @@ use {
     crate::{
         async_engine::SpawnedFuture,
         backend::{
-            Backend, Connector, ConnectorEvent, ConnectorId, ConnectorKernelId, DrmDeviceId,
+            Backend, Connector, ConnectorEvent, ConnectorId, ConnectorKernelId, DrmDeviceId, Mode,
         },
         video::drm::ConnectorType,
     },
@@ -56,4 +56,8 @@ impl Connector for DummyOutput {
     fn set_enabled(&self, _enabled: bool) {
         // nothing
     }
+
+    fn set_mode(&self, _mode: Mode) {
+        // nothing
+    }
 }

src/backends/metal/video.rs

@@ -3,7 +3,7 @@ use {
         async_engine::{Phase, SpawnedFuture},
         backend::{
             BackendDrmDevice, BackendEvent, Connector, ConnectorEvent, ConnectorId,
-            ConnectorKernelId, DrmDeviceId, HardwareCursor, MonitorInfo,
+            ConnectorKernelId, DrmDeviceId, HardwareCursor, Mode, MonitorInfo,
         },
         backends::metal::{MetalBackend, MetalError},
         drm_feedback::DrmFeedback,
@@ -155,7 +155,7 @@ pub struct ConnectorDisplayData {
     pub crtc_id: MutableProperty<DrmCrtc>,
     pub crtcs: AHashMap<DrmCrtc, Rc<MetalCrtc>>,
     pub modes: Vec<DrmModeInfo>,
-    pub mode: Option<Rc<DrmModeInfo>>,
+    pub mode: Option<DrmModeInfo>,
     pub refresh: u32,
 
     pub monitor_manufacturer: String,
@@ -862,6 +862,44 @@ impl Connector for MetalConnector {
     fn drm_feedback(&self) -> Option<Rc<DrmFeedback>> {
         self.drm_feedback.get()
     }
+
+    fn set_mode(&self, be_mode: Mode) {
+        let mut dd = self.display.borrow_mut();
+        let Some(mode) = dd.modes.iter().find(|m| m.to_backend() == be_mode) else {
+            log::warn!("Connector does not support mode {:?}", be_mode);
+            return;
+        };
+        let prev = dd.mode.clone();
+        if prev.as_ref() == Some(mode) {
+            return;
+        }
+        if dd.connection != ConnectorStatus::Connected {
+            log::warn!("Cannot change mode of connector that is not connected");
+            return;
+        }
+        let Some(dev) = self.backend.device_holder.drm_devices.get(&self.dev.devnum) else {
+            log::warn!("Cannot change mode because underlying device does not exist?");
+            return;
+        };
+        log::info!("Trying to change mode from {:?} to {:?}", prev, mode);
+        dd.mode = Some(mode.clone());
+        drop(dd);
+        let Err(e) = self.backend.handle_drm_change_(&dev, true) else {
+            self.on_change
+                .send_event(ConnectorEvent::ModeChanged(be_mode));
+            return;
+        };
+        log::warn!("Could not change mode: {}", ErrorFmt(&e));
+        self.display.borrow_mut().mode = prev;
+        if let MetalError::Modeset(DrmError::Atomic(OsError(c::EACCES))) = e {
+            log::warn!("Failed due to access denied. Resetting in memory only.");
+            return;
+        }
+        log::warn!("Trying to re-initialize the drm device");
+        if let Err(e) = self.backend.handle_drm_change_(&dev, true) {
+            log::warn!("Could not restore the previous mode: {}", ErrorFmt(e));
+        };
+    }
 }
 
 #[derive(Debug)]
@@ -1021,7 +1059,7 @@ fn create_connector_display_data(
     let mut name = String::new();
     let mut manufacturer = String::new();
     let mut serial_number = String::new();
-    let mode = info.modes.first().cloned().map(Rc::new);
+    let mode = info.modes.first().cloned();
     let refresh = mode
         .as_ref()
         .map(|m| 1_000_000_000_000u64 / (m.refresh_rate_millihz() as u64))
@@ -1402,6 +1440,13 @@ impl MetalBackend {
                 }
             };
             let mut old = c.display.borrow_mut();
+            if old.is_same_monitor(&dd) {
+                if let Some(mode) = &old.mode {
+                    if dd.modes.contains(mode) {
+                        dd.mode = Some(mode.clone());
+                    }
+                }
+            }
             mem::swap(old.deref_mut(), &mut dd);
             if c.connect_sent.get() {
                 if !c.enabled.get()

src/backends/x.rs

@@ -1058,6 +1058,10 @@ impl Connector for XOutput {
     fn set_enabled(&self, _enabled: bool) {
         // nothing
     }
+
+    fn set_mode(&self, _mode: Mode) {
+        log::warn!("X backend doesn't support changing the connector mode");
+    }
 }
 
 struct XSeat {

src/config/handler.rs

@@ -695,6 +695,20 @@ impl ConfigProxyHandler {
         Ok(())
     }
 
+    fn handle_connector_set_mode(
+        &self,
+        connector: Connector,
+        mode: WireMode,
+    ) -> Result<(), CphError> {
+        let connector = self.get_output(connector)?;
+        connector.connector.connector.set_mode(backend::Mode {
+            width: mode.width,
+            height: mode.height,
+            refresh_rate_millihz: mode.refresh_millihz,
+        });
+        Ok(())
+    }
+
     fn handle_connector_modes(&self, connector: Connector) -> Result<(), CphError> {
         let connector = self.get_output(connector)?;
         self.respond(Response::ConnectorModes {
@@ -1391,6 +1405,9 @@ impl ConfigProxyHandler {
             ClientMessage::ConnectorModes { connector } => self
                 .handle_connector_modes(connector)
                 .wrn("connector_modes")?,
+            ClientMessage::ConnectorSetMode { connector, mode } => self
+                .handle_connector_set_mode(connector, mode)
+                .wrn("connector_set_mode")?,
         }
         Ok(())
     }

src/it/test_backend.rs

@@ -246,6 +246,10 @@ impl Connector for TestConnector {
     fn set_enabled(&self, _enabled: bool) {
         // todo
     }
+
+    fn set_mode(&self, _mode: Mode) {
+        // todo
+    }
 }
 
 pub struct TestMouseClick {