kms: working state

src/backend/kms/crtc_mapping.rs

@@ -0,0 +1,329 @@
+// SPDX-License-Identifier: GPL-3.0-only
+
+use anyhow::Result;
+use smithay::{
+    reexports::drm::control::{
+        AtomicCommitFlags,
+        Device as ControlDevice,
+        ResourceHandle,
+        atomic::AtomicModeReq,
+        crtc,
+        connector::{
+            self,
+            State as ConnectorState,
+        },
+        dumbbuffer::DumbBuffer,
+        property,
+        Mode,
+        ModeFlags,
+    },
+};
+use std::collections::HashMap;
+
+pub fn display_configuration(device: &mut impl ControlDevice, supports_atomic: bool) -> Result<HashMap<connector::Handle, crtc::Handle>> {
+    let res_handles = device.resource_handles()?;
+    let connectors = res_handles.connectors();
+
+    let mut map = HashMap::new();
+    let mut cleanup = Vec::new();
+    // We expect the previous running drm master (likely the login mananger)
+    // to leave the drm device in a sensible state.
+    // That means, to reduce flickering, we try to keep an established mapping.
+    for conn in connectors
+        .iter()
+        .flat_map(|conn| device.get_connector(*conn).ok())
+    {
+        if let Some(enc) = device.get_connector(conn.handle())?.current_encoder() {
+            if let Some(crtc) = device.get_encoder(enc)?.crtc() {
+                // If is is connected we found a mapping
+                if conn.state() == ConnectorState::Connected {
+                    map.insert(conn.handle(), crtc);
+                // If not, the user just unplugged something,
+                // or the drm master did not cleanup?
+                // Well, I guess we cleanup after them.
+                } else {
+                    cleanup.push(crtc);
+                }
+            }
+        }
+    }
+    // But just in case we try to match all remaining connectors.
+    for conn in connectors
+        .iter()
+        .flat_map(|conn| device.get_connector(*conn).ok())
+        .filter(|conn| conn.state() == ConnectorState::Connected)
+        .filter(|conn| !map.contains_key(&conn.handle()))
+        .collect::<Vec<_>>().iter()
+    {
+        'outer: for encoder_info in conn
+            .encoders()
+            .iter()
+            .filter_map(|e| *e)
+            .flat_map(|encoder_handle| device.get_encoder(encoder_handle))
+        {
+            for crtc in res_handles.filter_crtcs(encoder_info.possible_crtcs()) {
+                if !map.values().any(|v| *v == crtc) {
+                    map.insert(conn.handle(), crtc);
+                    break 'outer;
+                }
+            }
+        }
+    }
+
+    // And then cleanup
+    if supports_atomic {
+        let mut req = AtomicModeReq::new();
+        let plane_handles = device.plane_handles()?;
+
+        for conn in connectors
+            .iter()
+            .flat_map(|conn| device.get_connector(*conn).ok())
+            .flat_map(|conn| conn.current_encoder())
+            .flat_map(|enc| device.get_encoder(enc).ok())
+            .flat_map(|enc| enc.crtc())
+            .filter(|c| cleanup.contains(&c))
+        {
+            let crtc_id = get_prop(device, conn, "CRTC_ID")?;
+            req.add_property(conn, crtc_id, property::Value::CRTC(None));
+        }
+
+        // We cannot just shortcut and use the legacy api for all cleanups because of this.
+        // (Technically a device does not need to be atomic for planes to be used, but nobody does this otherwise.)
+        for plane in plane_handles.planes() {
+            let info = device.get_plane(*plane)?;
+            if let Some(crtc) = info.crtc() {
+                if cleanup.contains(&crtc) {
+                    let crtc_id = get_prop(device, *plane, "CRTC_ID")?;
+                    let fb_id = get_prop(device, *plane, "FB_ID")?;
+                    req.add_property(*plane, crtc_id, property::Value::CRTC(None));
+                    req.add_property(*plane, fb_id, property::Value::Framebuffer(None));
+                }
+            }
+        }
+
+        for crtc in cleanup {
+            let mode_id = get_prop(device, crtc, "MODE_ID")?;
+            let active = get_prop(device, crtc, "ACTIVE")?;
+            req.add_property(crtc, active, property::Value::Boolean(false));
+            req.add_property(crtc, mode_id, property::Value::Unknown(0));
+        }
+
+        device.atomic_commit(AtomicCommitFlags::ALLOW_MODESET, req)?;
+    } else {
+        for crtc in cleanup {
+            #[allow(deprecated)]
+            let _ = device.set_cursor(crtc, Option::<&DumbBuffer>::None);
+            // null commit (necessary to trigger removal on the kernel side with the legacy api.)
+            let _ = device.set_crtc(crtc, None, (0, 0), &[], None);
+        }
+    }
+
+    Ok(map)
+}
+
+pub fn interface_name(device: &impl ControlDevice, connector: connector::Handle) -> Result<String> {
+    let conn_info = device.get_connector(connector)?;
+    
+    let other_short_name;
+    let interface_short_name = match conn_info.interface() {
+        connector::Interface::DVII => "DVI-I",
+        connector::Interface::DVID => "DVI-D",
+        connector::Interface::DVIA => "DVI-A",
+        connector::Interface::SVideo => "S-VIDEO",
+        connector::Interface::DisplayPort => "DP",
+        connector::Interface::HDMIA => "HDMI-A",
+        connector::Interface::HDMIB => "HDMI-B",
+        connector::Interface::EmbeddedDisplayPort => "eDP",
+        other => {
+            other_short_name = format!("{:?}", other);
+            &other_short_name
+        }
+    };
+    
+    Ok(format!("{}-{}", interface_short_name, conn_info.interface_id()))   
+}
+
+pub struct EdidInfo {
+    pub model: String,
+    pub manufacturer: String,
+}
+
+pub fn edid_info(device: &impl ControlDevice, connector: connector::Handle) -> Result<EdidInfo> {
+    use edid_rs::{parse as edid_parse, MonitorDescriptor};
+
+    let edid_prop = get_prop(device, connector, "EDID")?;
+    let edid_info = device.get_property(edid_prop)?;
+    let mut manufacturer = "Unknown".into();
+    let mut model = "Unknown".into();
+    let props = device.get_properties(connector)?;
+    let (ids, vals) = props.as_props_and_values();
+    for (&id, &val) in ids.iter().zip(vals.iter()) {
+        if id == edid_prop {
+            if let property::Value::Blob(edid_blob) =
+                edid_info.value_type().convert_value(val)
+            {
+                let blob = device.get_property_blob(edid_blob)?;
+                let mut reader = std::io::Cursor::new(blob);
+                if let Some(edid) = edid_parse(&mut reader).ok() {
+                    manufacturer = {
+                        let id = edid.product.manufacturer_id;
+                        let code = [id.0, id.1, id.2];
+                        get_manufacturer(&code).into()
+                    };
+                    model = if let Some(MonitorDescriptor::MonitorName(name)) = edid.descriptors.0
+                        .iter()
+                        .find(|x| matches!(x, MonitorDescriptor::MonitorName(_)))
+                    {
+                        name.clone()
+                    } else {
+                        format!("{}", edid.product.product_code)
+                    };
+                }
+            }
+            break;
+        }
+    }
+
+    Ok(EdidInfo {
+        model,
+        manufacturer,
+    })
+}
+
+pub fn get_prop(device: &impl ControlDevice, handle: impl ResourceHandle, name: &str) -> Result<property::Handle> {
+    let props = device.get_properties(handle)?;
+    let (prop_handles, _) = props.as_props_and_values();
+    for prop in prop_handles {
+        let info = device.get_property(*prop)?;
+        if Some(name) == info.name().to_str().ok() {
+            return Ok(*prop);
+        }
+    }
+    anyhow::bail!("No prop found")
+}
+
+pub fn get_property_val(device: &impl ControlDevice, handle: impl ResourceHandle, name: &str) -> Result<(property::ValueType, property::RawValue)> {
+    let props = device.get_properties(handle)?;
+    let (prop_handles, values) = props.as_props_and_values();
+    for (&prop, &val) in prop_handles.iter().zip(values.iter()) {
+        let info = device.get_property(prop)?;
+        if Some(name) == info.name().to_str().ok() {
+            let val_type = info.value_type();
+            return Ok((val_type, val));
+        }
+    }
+    anyhow::bail!("No prop found")
+}
+
+fn get_manufacturer(vendor: &[char; 3]) -> &'static str {
+	match vendor {
+	    ['A', 'A', 'A'] => "Avolites Ltd",
+	    ['A', 'C', 'I'] => "Ancor Communications Inc",
+	    ['A', 'C', 'R'] => "Acer Technologies",
+	    ['A', 'D', 'A'] => "Addi-Data GmbH",
+	    ['A', 'P', 'P'] => "Apple Computer Inc",
+	    ['A', 'S', 'K'] => "Ask A/S",
+	    ['A', 'V', 'T'] => "Avtek (Electronics) Pty Ltd",
+	    ['B', 'N', 'O'] => "Bang & Olufsen",
+	    ['B', 'N', 'Q'] => "BenQ Corporation",
+	    ['C', 'M', 'N'] => "Chimei Innolux Corporation",
+	    ['C', 'M', 'O'] => "Chi Mei Optoelectronics corp.",
+	    ['C', 'R', 'O'] => "Extraordinary Technologies PTY Limited",
+	    ['D', 'E', 'L'] => "Dell Inc.",
+	    ['D', 'G', 'C'] => "Data General Corporation",
+	    ['D', 'O', 'N'] => "DENON, Ltd.",
+	    ['E', 'N', 'C'] => "Eizo Nanao Corporation",
+	    ['E', 'P', 'H'] => "Epiphan Systems Inc.",
+	    ['E', 'X', 'P'] => "Data Export Corporation",
+	    ['F', 'N', 'I'] => "Funai Electric Co., Ltd.",
+	    ['F', 'U', 'S'] => "Fujitsu Siemens Computers GmbH",
+	    ['G', 'S', 'M'] => "Goldstar Company Ltd",
+	    ['H', 'I', 'Q'] => "Kaohsiung Opto Electronics Americas, Inc.",
+	    ['H', 'S', 'D'] => "HannStar Display Corp",
+	    ['H', 'T', 'C'] => "Hitachi Ltd",
+	    ['H', 'W', 'P'] => "Hewlett Packard",
+	    ['I', 'N', 'T'] => "Interphase Corporation",
+	    ['I', 'N', 'X'] => "Communications Supply Corporation (A division of WESCO)",
+	    ['I', 'T', 'E'] => "Integrated Tech Express Inc",
+	    ['I', 'V', 'M'] => "Iiyama North America",
+	    ['L', 'E', 'N'] => "Lenovo Group Limited",
+	    ['M', 'A', 'X'] => "Rogen Tech Distribution Inc",
+	    ['M', 'E', 'G'] => "Abeam Tech Ltd",
+	    ['M', 'E', 'I'] => "Panasonic Industry Company",
+	    ['M', 'T', 'C'] => "Mars-Tech Corporation",
+	    ['M', 'T', 'X'] => "Matrox",
+	    ['N', 'E', 'C'] => "NEC Corporation",
+	    ['N', 'E', 'X'] => "Nexgen Mediatech Inc.",
+	    ['O', 'N', 'K'] => "ONKYO Corporation",
+	    ['O', 'R', 'N'] => "ORION ELECTRIC CO., LTD.",
+	    ['O', 'T', 'M'] => "Optoma Corporation",
+	    ['O', 'V', 'R'] => "Oculus VR, Inc.",
+	    ['P', 'H', 'L'] => "Philips Consumer Electronics Company",
+	    ['P', 'I', 'O'] => "Pioneer Electronic Corporation",
+	    ['P', 'N', 'R'] => "Planar Systems, Inc.",
+	    ['Q', 'D', 'S'] => "Quanta Display Inc.",
+	    ['R', 'A', 'T'] => "Rent-A-Tech",
+	    ['R', 'E', 'N'] => "Renesas Technology Corp.",
+	    ['S', 'A', 'M'] => "Samsung Electric Company",
+	    ['S', 'A', 'N'] => "Sanyo Electric Co., Ltd.",
+	    ['S', 'E', 'C'] => "Seiko Epson Corporation",
+	    ['S', 'H', 'P'] => "Sharp Corporation",
+	    ['S', 'I', 'I'] => "Silicon Image, Inc.",
+	    ['S', 'N', 'Y'] => "Sony",
+	    ['S', 'T', 'D'] => "STD Computer Inc",
+	    ['S', 'V', 'S'] => "SVSI",
+	    ['S', 'Y', 'N'] => "Synaptics Inc",
+	    ['T', 'C', 'L'] => "Technical Concepts Ltd",
+	    ['T', 'O', 'P'] => "Orion Communications Co., Ltd.",
+	    ['T', 'S', 'B'] => "Toshiba America Info Systems Inc",
+	    ['T', 'S', 'T'] => "Transtream Inc",
+	    ['U', 'N', 'K'] => "Unknown",
+	    ['V', 'E', 'S'] => "Vestel Elektronik Sanayi ve Ticaret A. S.",
+	    ['V', 'I', 'T'] => "Visitech AS",
+	    ['V', 'I', 'Z'] => "VIZIO, Inc",
+	    ['V', 'S', 'C'] => "ViewSonic Corporation",
+	    ['Y', 'M', 'H'] => "Yamaha Corporation",
+	    _ => "Unknown",
+    }
+}
+
+pub fn calculate_refresh_rate(mode: Mode) -> u32 {
+    let htotal = mode.hsync().2 as u32;
+    let vtotal = mode.vsync().2 as u32;
+	let mut refresh = (mode.clock() as u64 * 1000000_u64 / htotal as u64 +
+        vtotal as u64 / 2) / vtotal as u64;
+
+	if mode.flags().contains(ModeFlags::INTERLACE) {
+		refresh *= 2;
+	}
+	if mode.flags().contains(ModeFlags::DBLSCAN) {
+		refresh /= 2;
+	}
+	if mode.vscan() > 1 {
+		refresh /= mode.vscan() as u64;
+	}
+
+	refresh as u32
+}
+
+pub fn supports_vrr(dev: &impl ControlDevice, conn: connector::Handle) -> Result<bool> {
+    get_property_val(dev, conn, "vrr_capable")
+        .map(|(val_type, val)| match val_type.convert_value(val) {
+            property::Value::UnsignedRange(res) => res == 1,
+            _ => false,
+        })
+}
+
+pub fn set_vrr(dev: &impl ControlDevice, crtc: crtc::Handle, conn: connector::Handle, vrr: bool) -> Result<bool> {
+    if supports_vrr(dev, conn)? {
+        dev.set_property(conn, get_prop(dev, crtc, "VRR_ENABLED")?, property::Value::UnsignedRange(if vrr { 1 } else { 0 }).into())
+            .map_err(Into::<anyhow::Error>::into)
+            .and_then(|_| get_property_val(dev, crtc, "VRR_ENABLED"))
+            .map(|(val_type, val)| match val_type.convert_value(val) {
+                property::Value::UnsignedRange(vrr) => vrr == 1,
+                _ => false,
+            })
+    } else {
+        Ok(false)
+    }
+}

src/backend/kms/mod.rs

@@ -1,17 +1,428 @@
 // SPDX-License-Identifier: GPL-3.0-only
 
-use crate::state::State;
-use anyhow::Result;
-use smithay::reexports::calloop::EventLoop;
+use crate::{
+    state::{BackendData, Common, State},
+    utils::GlobalDrop,
+};
+use anyhow::{Context, Result};
+use smithay::{
+    backend::{
+        allocator::{gbm::GbmDevice, Format},
+        drm::{DrmDevice, DrmEvent, GbmBufferedSurface, DrmEventTime},
+        egl::{EGLDevice, EGLDisplay, EGLContext},
+        libinput::{LibinputInputBackend, LibinputSessionInterface},
+        session::{Session, Signal, auto::AutoSession, AsErrno},
+        udev::{UdevBackend, UdevEvent, primary_gpu},
+        renderer::{Bind, gles2::Gles2Renderer},
+    },
+    reexports::{
+        drm::{
+            control::{
+                Device as ControlDevice,
+                connector,
+                crtc,
+            },
+        },
+        calloop::{EventLoop, Dispatcher, RegistrationToken, LoopHandle, timer::{Timer, TimerHandle}},
+        input::Libinput,
+        nix::{
+            fcntl::OFlag,
+            sys::stat::dev_t,
+        },
+        wayland_server::{
+            Display,
+            protocol::wl_output,
+        }
+    },
+    wayland::output::{Output, Mode as OutputMode, PhysicalProperties},
+    utils::signaling::{Signaler, Linkable},
+};
+use std::{
+    cell::RefCell,
+    collections::{HashMap, HashSet},
+    path::PathBuf,
+    rc::Rc,
+    time::{Duration, Instant, SystemTime},
+};
 
-pub struct KmsState {}
+mod crtc_mapping;
+mod session_fd;
+use session_fd::*;
+
+pub struct KmsState {
+    devices: HashMap<dev_t, Device>,
+    session: AutoSession,
+    signaler: Signaler<Signal>,
+    tokens: Vec<RegistrationToken>,
+}
+
+pub struct Device {
+    renderer: Gles2Renderer,
+    surfaces: HashMap<crtc::Handle, Surface>,
+    allocator: Rc<RefCell<GbmDevice<SessionFd>>>,
+    drm: Dispatcher<'static, DrmDevice<SessionFd>, State>,
+    formats: HashSet<Format>,
+    supports_atomic: bool,
+    event_token: Option<RegistrationToken>,
+}
+
+pub struct Surface {
+    surface: GbmBufferedSurface<Rc<RefCell<GbmDevice<SessionFd>>>, SessionFd>,
+    output: Output,
+    _global: GlobalDrop<wl_output::WlOutput>,
+    last_submit: Option<DrmEventTime>,
+    refresh_rate: u32,
+    vrr: bool,
+    pending: bool,
+    render_timer: TimerHandle<(dev_t, crtc::Handle)>,
+    render_timer_token: Option<RegistrationToken>,
+}
+
+#[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
+pub struct DevId(pub dev_t);
 
 pub fn init_backend(event_loop: &mut EventLoop<State>, state: &mut State) -> Result<()> {
-    unimplemented!()
+    let (session, notifier) = AutoSession::new(None).context("Failed to acquire session")?;
+    let signaler = notifier.signaler();
+
+    let udev_backend = UdevBackend::new(session.seat(), None)?;
+    let mut libinput_context = Libinput::new_with_udev::<LibinputSessionInterface<AutoSession>>(session.clone().into());
+    libinput_context.udev_assign_seat(&session.seat()).map_err(|_| anyhow::anyhow!("Failed to assign seat to libinput"))?;
+    let mut libinput_backend = LibinputInputBackend::new(libinput_context, None);
+    libinput_backend.link(signaler.clone());
+
+    let libinput_event_source = event_loop
+        .handle()
+        .insert_source(libinput_backend, move |event, _, state| {
+            state.common.process_input_event(event);
+            for output in state.common.spaces.outputs() {
+                state.backend.kms().schedule_render(output);
+            }
+        })
+        .map_err(|err| err.error)
+        .context("Failed to initialize libinput event source")?;
+    let session_event_source = event_loop
+        .handle()
+        .insert_source(notifier, |(), &mut (), _state| {})
+        .map_err(|err| err.error)
+        .context("Failed to initialize session event source")?;
+
+    state.backend = BackendData::Kms(KmsState {
+        tokens: vec![
+            libinput_event_source,
+            session_event_source,
+        ],
+        session,
+        signaler,
+        devices: HashMap::new(),
+    });
+
+    for (dev, path) in udev_backend.device_list() {
+        state.device_added(dev, path.into())
+            .with_context(|| format!("Failed to add drm device: {}", path.display()))?;
+    }
+
+    let udev_event_source = event_loop
+        .handle()
+        .insert_source(udev_backend, move |event, _, state| match match event {
+            UdevEvent::Added { device_id, path } => state.device_added(device_id, path)
+                    .with_context(|| format!("Failed to add drm device: {}", device_id)),
+            UdevEvent::Changed { device_id } => state.device_changed(device_id)
+                    .with_context(|| format!("Failed to update drm device: {}", device_id)),
+            UdevEvent::Removed { device_id } => state.device_removed(device_id)
+                    .with_context(|| format!("Failed to remove drm device: {}", device_id)),
+        } {
+            Ok(()) => { slog_scope::debug!("Successfully handled udev event") },
+            Err(err) => { slog_scope::error!("Error while handling udev event: {}", err) },
+        }).unwrap();
+    state.backend.kms().tokens.push(udev_event_source);
+
+    Ok(())
+}
+
+impl State {
+    fn device_added(&mut self, dev: dev_t, path: PathBuf) -> Result<()> {
+        let fd = SessionFd::new(self.backend.kms().session.open(&path, OFlag::O_RDWR | OFlag::O_CLOEXEC | OFlag::O_NOCTTY | OFlag::O_NONBLOCK)
+            .with_context(|| format!("Failed to optain file descriptor for drm device: {}", path.display()))?);
+        let mut drm = DrmDevice::new(fd.clone(), false, None)
+            .with_context(|| format!("Failed to initialize drm device for: {}", path.display()))?;
+        let supports_atomic = drm.is_atomic();
+
+        let egl_device = EGLDevice::enumerate().context("Failed to enumerate EGLDevices")?
+            // TODO: this check compares the primary node path.
+            // On split display controller setups however this *may* return the render node
+            // *or* if `EGL_EXT_device_drm_render_node` is supported nothing and we need to
+            // query `EGL_DRM_RENDER_NODE_FILE_EXT` instead for comparision.
+            .find(|dev| dev.drm_device_path().map(|p| p == path).unwrap_or(false))
+            .with_context(|| format!("Unable to find matching egl device for {}", path.display()))?;
+        let egl_display = EGLDisplay::new(&egl_device, None)
+            .with_context(|| format!("Failed to open EGLDisplay for device {:?}:{}", egl_device, path.display()))?;
+        let egl_context = EGLContext::new(&egl_display, None)
+            .with_context(|| format!("Failed to create EGLContext for device {:?}:{}", egl_device, path.display()))?;
+        let formats = egl_context.dmabuf_render_formats().clone();
+        let renderer = unsafe { Gles2Renderer::new(egl_context, None) }
+            .with_context(|| format!("Failed to create OpenGLES renderer for device {:?}:{}", egl_device, path.display()))?;
+
+        let gbm = GbmDevice::new(fd).with_context(|| format!("Failed to initialize GBM device for {}", path.display()))?;
+        drm.link(self.backend.kms().signaler.clone());
+        let dispatcher = Dispatcher::new(drm, move |event, metadata, state: &mut State| {
+            match event {
+                DrmEvent::VBlank(crtc) => {
+                    if let Some(device) = state.backend.kms().devices.get_mut(&dev) {
+                        if let Some(surface) = device.surfaces.get_mut(&crtc) {
+                            match surface.surface.frame_submitted() {
+                                Ok(_) => {
+                                    surface.last_submit = metadata.take().map(|data| data.time);
+                                    surface.pending = false;
+                                    state.common.spaces.active_space_mut(&surface.output)
+                                        .send_frames(true, state.common.start_time.elapsed().as_millis() as u32);
+                                },
+                                Err(err) => slog_scope::warn!("Failed to submit frame: {}", err),
+                            };
+                        }
+                    }
+                },
+                DrmEvent::Error(err) => {
+                    slog_scope::warn!("Failed to read events of device {:?}: {}", dev, err);
+                }
+            }
+        });
+        let token = self.common.event_loop_handle.register_dispatcher(dispatcher.clone())
+            .with_context(|| format!("Failed to add drm device to event loop: {}", dev))?;
+
+        let mut device = Device {
+            renderer,
+            surfaces: HashMap::new(),
+            allocator: Rc::new(RefCell::new(gbm)),
+            drm: dispatcher,
+            formats,
+            supports_atomic,
+            event_token: Some(token),
+        };
+
+        let outputs = device.enumerate_surfaces()?.added; // There are no removed outputs on newly added devices
+        for (crtc, conn) in outputs {
+            match device.setup_surface(crtc, conn, self.backend.kms().signaler.clone(), &mut self.common.display.borrow_mut(), &mut self.common.event_loop_handle) {
+                Ok(output) => self.common.spaces.map_output(&output),
+                Err(err) => slog_scope::warn!("Failed to initialize output: {}", err),
+            };
+        }
+
+        self.backend.kms().devices.insert(dev, device);
+        Ok(())
+    }
+
+    fn device_changed(&mut self, dev: dev_t) -> Result<()> {
+        let signaler = self.backend.kms().signaler.clone();
+        if let Some(device) = self.backend.kms().devices.get_mut(&dev) {
+            let changes = device.enumerate_surfaces()?;
+            for (crtc, _) in changes.removed {
+                if let Some(surface) = device.surfaces.get_mut(&crtc) {
+                    if let Some(token) = surface.render_timer_token.take() {
+                        self.common.event_loop_handle.remove(token);
+                    }
+                    self.common.spaces.unmap_output(&surface.output);
+                }
+            }
+            for (crtc, conn) in changes.added {
+                match device.setup_surface(crtc, conn, signaler.clone(), &mut self.common.display.borrow_mut(), &mut self.common.event_loop_handle) {
+                    Ok(output) => self.common.spaces.map_output(&output),
+                    Err(err) => slog_scope::warn!("Failed to initialize output: {}", err),
+                };
+            }
+        }
+        Ok(())
+    }
+
+    fn device_removed(&mut self, dev: dev_t) -> Result<()> {
+        if let Some(device) = self.backend.kms().devices.get_mut(&dev) {
+            for surface in device.surfaces.values_mut() {
+                if let Some(token) = surface.render_timer_token.take() {
+                    self.common.event_loop_handle.remove(token);
+                }
+                self.common.spaces.unmap_output(&surface.output);
+            }
+            if let Some(token) = device.event_token.take() {
+                self.common.event_loop_handle.remove(token);
+            }
+        }
+        Ok(())
+    }
+}
+
+pub struct OutputChanges {
+    pub added: Vec<(crtc::Handle, connector::Handle)>,
+    pub removed: Vec<(crtc::Handle, connector::Handle)>,
+}
+
+impl Device {
+    pub fn enumerate_surfaces(&mut self) -> Result<OutputChanges> {
+        let drm = &mut *self.drm.as_source_mut();
+
+        // enumerate our outputs
+        let config = crtc_mapping::display_configuration(drm, self.supports_atomic)?;
+
+        let surfaces = self.surfaces.iter()
+            .map(|(c, s)| (*c, s.surface.current_connectors().into_iter().next().unwrap()))
+            .collect::<HashMap<crtc::Handle, connector::Handle>>();
+        
+        let added = config.iter()
+            .filter(|(conn, crtc)| surfaces.get(&crtc).map(|c| c != *conn).unwrap_or(true))
+            .map(|(conn, crtc)| (crtc, conn))
+            .map(|(crtc, conn)| (*crtc, *conn))
+            .collect::<Vec<_>>();
+        let removed = surfaces.iter()
+            .filter(|(crtc, conn)| config.get(&conn).map(|c| c != *crtc).unwrap_or(true))
+            .map(|(crtc, conn)| (*crtc, *conn))
+            .collect::<Vec<_>>();
+
+        Ok(OutputChanges {
+            added,
+            removed,
+        })
+    }
+
+    fn setup_surface(
+        &mut self,
+        crtc: crtc::Handle,
+        conn: connector::Handle,
+        signaler: Signaler<Signal>,
+        display: &mut Display,
+        loop_handle: &mut LoopHandle<'static, State>,
+    ) -> Result<Output> {
+        let drm = &mut *self.drm.as_source_mut();
+        let crtc_info = drm.get_crtc(crtc)?;
+        let conn_info = drm.get_connector(conn)?;
+        let vrr = crtc_mapping::set_vrr(drm, crtc, conn, true)?;
+        let interface = crtc_mapping::interface_name(drm, conn)?;
+        let edid_info = crtc_mapping::edid_info(drm, conn)?;
+        let mode = crtc_info.mode().unwrap_or(conn_info.modes()[0]);
+        let mut surface = drm.create_surface(crtc, mode, &[conn])?;
+        surface.link(signaler);
+
+        let target = GbmBufferedSurface::new(surface, self.allocator.clone(), self.formats.clone(), None)
+            .with_context(|| format!("Failed to initialize Gbm surface for {}", interface))?;
+
+        let output_mode = OutputMode {
+            size: (mode.size().0 as i32, mode.size().1 as i32).into(),
+            refresh: (mode.vrefresh() * 1000) as i32,
+        };
+        let (phys_w, phys_h) = conn_info.size().unwrap_or((0, 0));
+        let (output, output_global) = Output::new(
+            display,
+            interface,
+            PhysicalProperties {
+                size: (phys_w as i32, phys_h as i32).into(),
+                // TODO: We need to read that from the connector properties
+                subpixel: wl_output::Subpixel::Unknown,
+                make: edid_info.manufacturer,
+                model: edid_info.model,
+            },
+            None
+        );
+        output.set_preferred(output_mode.clone());
+        output.change_current_state(
+            Some(output_mode),
+            None, // TODO: Readout property for monitor rotation
+            None,
+            None,
+        );
+
+        let timer = Timer::new()?;
+        let timer_handle = timer.handle();
+        // render timer
+        let timer_token = loop_handle
+            .insert_source(timer, |(dev_id, crtc), _, state| {
+                if let Some(device) = state.backend.kms().devices.get_mut(&dev_id) {
+                    let renderer = &mut device.renderer;
+                    if let Some(surface) = device.surfaces.get_mut(&crtc) {
+                        if let Err(err) = surface.render_output(renderer, &mut state.common) {
+                            slog_scope::error!("Error rendering: {}", err);
+                            // TODO re-schedule?
+                        }
+                    }
+                }
+            })
+            .unwrap();
+        timer_handle.add_timeout(Duration::ZERO, (drm.device_id(), crtc));
+
+        let data = Surface {
+            output: output.clone(),
+            _global: output_global.into(),
+            surface: target,
+            vrr,
+            refresh_rate: crtc_mapping::calculate_refresh_rate(mode),
+            last_submit: None,
+            pending: true,
+            render_timer: timer_handle,
+            render_timer_token: Some(timer_token),
+        };
+        self.surfaces.insert(crtc, data);
+
+        Ok(output)
+    }
+}
+
+impl Surface {
+    pub fn render_output(
+        &mut self,
+        renderer: &mut Gles2Renderer,
+        state: &mut Common,
+    ) -> Result<()> {
+        let custom_elements = Vec::new();
+
+        let space = state.spaces.active_space_mut(&self.output);
+        let (buffer, age) = self
+            .surface
+            .next_buffer()
+            .with_context(|| "Failed to allocate buffer")?;
+        renderer
+            .bind(buffer)
+            .with_context(|| "Failed to bind buffer")?;
+        match space.render_output(
+            renderer,
+            &self.output,
+            age as usize,
+            [0.153, 0.161, 0.165, 1.0],
+            &*custom_elements,
+        ) {
+            Ok(_) => {
+                self.surface
+                    .queue_buffer()
+                    .with_context(|| "Failed to submit buffer for display")?;
+            }
+            Err(err) => {
+                self.surface.reset_buffers();
+                anyhow::bail!("Rendering failed: {}", err);
+            }
+        };
+        Ok(())
+    }
 }
 
 impl KmsState {
     pub fn schedule_render(&mut self, output: &Output) {
-        unimplemented!();
+        if let Some((device, surface)) = self.devices.values_mut()
+            .flat_map(|d| {
+                let dev_id = d.drm.as_source_ref().device_id();
+                d.surfaces.values_mut().map(move |s| (dev_id, s))
+            })
+            .find(|(_, s)| s.output == *output)
+        {
+            if !surface.pending {
+                surface.pending = true;
+                let duration = match surface.last_submit {
+                    Some(DrmEventTime::Monotonic(instant)) => Instant::now().duration_since(instant),
+                    Some(DrmEventTime::Realtime(time)) => SystemTime::now().duration_since(time).unwrap_or(Duration::new(100, 0)),
+                    None => Duration::new(100, 0), // Just do an insane amount
+                };
+                let data = (device, surface.surface.crtc());
+                if surface.vrr || 1.0 / (surface.refresh_rate as f64) < duration.as_secs_f64() / 1000.0 {
+                    surface.render_timer.add_timeout(Duration::ZERO, data);
+                } else {
+                    surface.render_timer.add_timeout(duration.saturating_sub(Duration::from_millis(5)), data);
+                }
+            }
+        }
     }
 }

src/backend/kms/session_fd.rs

@@ -0,0 +1,37 @@
+use std::{
+    fmt,
+    rc::Rc,
+    os::unix::io::{RawFd, AsRawFd},
+};
+use smithay::reexports::nix::unistd::close;
+
+#[derive(Clone)]
+pub struct SessionFd(Rc<DropFd>);
+
+struct DropFd(RawFd);
+
+impl SessionFd {
+    pub fn new(fd: RawFd) -> SessionFd {
+        SessionFd(Rc::new(DropFd(fd)))
+    }
+}
+
+impl fmt::Debug for SessionFd {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Session-provided File Descriptor [{}]", self.0.0)
+    }
+}
+
+impl AsRawFd for SessionFd {
+    fn as_raw_fd(&self) -> RawFd {
+        self.0.0
+    }
+}
+
+impl Drop for DropFd {
+    fn drop(&mut self) {
+        if let Err(err) = close(self.0) {
+            slog_scope::warn!("Failed to close file descriptor {}", self.0);
+        }
+    }
+}