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diff --git a/docs/0-waltham-overview.md b/docs/0-waltham-overview.md new file mode 100644 index 0000000..78f2596 --- /dev/null +++ b/docs/0-waltham-overview.md @@ -0,0 +1,76 @@ +**Table of Content** + +1. TOC +{:toc} + +## Context + +In today's world, the information for drivers is becoming excessive. For +example, safety information to let the driver notice the obstacles on the road, +telematics information about car accident or traffic jam, media information +from connected phones etc. In the future, it is expected that the +more displays will be available in the car and show more information. + +TFT (Thin-Film transistor) Cluster will have more information, other than +engine speed and a map, with a Head-Up-Display projected onto the windshield +will bring driver to new world. With the constant bombardment of information +drivers will have a hard time making sure their eyes on the road, avoiding +needless distractions. + +As we need more comprehensive Human Machine Interfaces, which displays the +information that the driver needs on appropriate device and on time with +a comprehensive user interface, a screen-sharing, remoting mechanism between +multiple ECUs (Electronic Control Unit) will be necessary. For that, a protocol +working over the network has been devised that could solve this problem. + +## Waltham protocol + +[Waltham protocol](https://github.com/waltham/waltham) is a IPC library similar +to [Wayland](https://wayland.freedesktop.org), developed with networking in +mind. It operates over TCP sockets, while the wayland protocol only +works locally over a UNIX socket. It retains wayland-esque paradigm, making use +of XMLs to describe the protocol, and it follows an object-oriented design with +an asynchronous architecture. + +It was developed by Collabora Ltd., along with ADIT, a joint venture company +owned by Robert Bosch Car Multimedia GmbH and DENSO corporation. It supports +surface sharing via network, but sharing function itself is not implemented in +Waltham. Please refer [Waltham +documentation](https://waltham.github.io/waltham/) for more details. + +### Major differences from Wayland to Waltham +- Waltham uses TCP sockets for reliable communication +- Waltham cannot send file descriptors +- Waltham API is minimal and symmetric between server and client sides +- Waltham does not provide an event loop implementation +- The registry implementation is left out of the library, only the interface is + provided +- No multi-threading support for sharing objects between threads + + + +### Requirements in automotive industry +In order to use Waltham in automotive industry, the automotive specific +requirements must be covered. + +The below shows very high level requirements. You can find the further +requirements at [**Waltham Requirements**](https://confluence.automotivelinux.org/display/UIGRA/Waltham+backend+requirements). + +1. Shall be able to support fast/reliable remoting among multiple ECUs +2. Shall be able to support input handling +3. Shall be able to share dedicated application +4. Shall be able to share complete display output depending on additional + communication + +* Surface sharing is not part of Waltham protocol, each system needs to +implement the most efficient way for surface sharing. On AGL, we implemented +[Waltham client and Receiver](1-waltham-client-and-receiver.md) to enable +surface sharing along with GStreamer encoder/decoder. It uses UDP for remoting, +which is faster than TCP. Input events communicates with Waltham +protocol. + +### Links +* [Announcement of Waltham](https://lists.freedesktop.org/archives/wayland-devel/2016-October/031413.html) +* [Bi-weekly meeting minutes](https://wiki.automotivelinux.org/eg-ui-graphics) +* [UI and Graphics wiki](https://confluence.automotivelinux.org/display/UIGRA/UI+and+Graphics+Home) +* [Waltham source codes](https://gerrit.automotivelinux.org/gerrit/gitweb?p=src/weston-ivi-plugins.git;a=tree;h=refs/heads/master;hb=refs/heads/master) diff --git a/docs/1-waltham-client-and-receiver.md b/docs/1-waltham-client-and-receiver.md new file mode 100644 index 0000000..2396972 --- /dev/null +++ b/docs/1-waltham-client-and-receiver.md @@ -0,0 +1,156 @@ +**Table of Content** + +1. TOC +{:toc} + +## waltham-client-server-applications + + + +### waltham-transmitter-plugin + +*waltham-transmitter-plugin* provides an API to create remote connections and +push surfaces over the network and handles remote input. It is loaded +automatically at start-up, by the compositor. The (remote) outputs are streamed +to the remote side by using the remoting plug-in. + +### waltham-receiver + +waltham-receiver is a sample implementation of the receiver app which should be +running at the remote side. It is developed based on [waltham +server](https://github.com/waltham/waltham/tree/master/tests), using Waltham +protocol to obtain and process remote input -- handled by +waltham-transmitter-plugin, with the remote output handled by the remoting +plugin. This component is designed to be used for evaluating the functionality +of waltham-transmitter plugin. + +## How it works + +### 1. Loading and initialization + +As the compositor is starting up, it loads the waltham-transmitter plugin. + + + +### 2. Establishing connection + +At `transmitter_create_remote()`, waltham-transmitter creates +`weston_transmitter_remote` object which expresses the receiver object at +remote side, and it is created for each receiver. + +*waltham-transmitter* uses `wth_display_get_registry()` and `wth_display_sync()` +for the receiver applications in the same manner as the Wayland protocol +would retrieve the interfaces. Then, the receiver applications sends back +the resource list to the waltham-transmitter. + + + +### 3. Forwarding surface + +A fake mechanism of sending the buffer attachments was previously in place. The +following protocol messages to the receiver app were added to notify about +surface updates. + +`wthp_surface_attach()`, `wthp_surface_damage()` and `wthp_surface_commit()` +correspond to `wl_surface_attach()`, `wl_surface_damage()` and +`wl_surface_commit()` message in wayland protocol. + +- `wthp_surface_attach()` - Send wthp_buffer as a buffer handling. This is not +the actual buffer which contains the data to be rendered but the handle of an +actual buffer. It abstracts the differences of buffer type. +- `wthp_surface_damage()` - Tell the updated region to receiver app. +- `wthp_surface_commit()` - Tell surface gets updated to receiver app. + +These are no longer in place, as the remoting output is being handled entirely +by the remoting plugin. + + + +### 4. Rendering using GStreamer + + + +### 5. Input handling + +For handling input events, waltham-transmitter has 2 ways to secure seat. + +1. Use `wl_seat` as weston has. +2. Create a new `wl_seat`. + +Second case is applicable in case the transmitter side does not have an input +device but the receiver at remote side has one. After `wl_seat` is created, +waltham-transmitter sends input events to the client application when +it gets an input event from the receiver via the Waltham protocol. + +The message wthp_send_XXX shows you that input event is forwarded from the +receiver to the transmitter, XXX is filled by the input event name. + + + +### 6. Retry connection + +In case the connection gets disconnected during surface sharing, +waltham-transmitter shall re-establish the connection. The `waltham_display` +objects represents the connection between the transmitter and the receiver, +and contains a flag that can be used to detect a disconnect. + +That happens in `connection_handle_data()` in case a disconnect is detected. +This flag is checked at every call of `transmitter_surface_gather_state`. When +running is in false state, waltham-transmitter starts to retry the handling +sequence. + +It release the waltham protocol objects then it goes to establish a connection +sequence mentioned in 2. Establishing connection. + + + +## Waltham in practice + +Here is the example how waltham can be used in hypervisor use case of real +project. + +* Weston is used as the wayland compositor. +* waltham-client is implemented for Weston which acts as a Waltham virtual + display. +* Application surface is assigned to Waltham virtual display and it's sent to + the other ECU/OS. Buffers of surface are transferred via GStreamer(UDP), + since transferring raw pixel data via Waltham(TCP) is not fast enough. +* Controlling input events (pointer, keyboard, touch) for the surface is + handled by Waltham. + + + +## How Waltham can be integrated + +Some possible integration examples of waltham follow. + +### As an EGL backend (theoretical possibility) + +Similarly to Wayland back-end for EGL, Waltham client could be a back-end in +the compositor. For better performance, a generic surface sharing mechanism is +needed in a hypervisor environment. Applications need to adapt to Waltham. +As waltham is not designed with this use in mind this usage is just a +theoretical possibility. + + + +### As a GStreamer sink (theoretical possibility) + +Similarly to Wayland sink, a Waltham sink GStreamer plugin can be implemented +which sends the buffers to a receiver on another domain/OS. Waltham sink can +utilize frame synchronization and a presentation feedback protocols for video +synchronization. For better performance, a generic surface sharing mechanism +is needed in a hypervisor environment. As Waltham is not designed with this +use in mind this usage is just a theoretical possibility. + + + +### As a virtual display in compositor + +Virtual display plugin can be implemented in the compositor. This plugin sends +client buffers to waltham-receiver in another domain. No changes to +applications. For good performance, a generic surface sharing mechanism is +needed in hypervisor environment. This is the intended use in mind during +design. + + diff --git a/docs/2-waltham-how-to-build.md b/docs/2-waltham-how-to-build.md new file mode 100644 index 0000000..350e728 --- /dev/null +++ b/docs/2-waltham-how-to-build.md @@ -0,0 +1,108 @@ +**Table of Content** + +1. TOC +{:toc} + +## Information + +## How to build waltham-transmitter-plugin + +1. Go to AGL build folder and configure your environment. Add +'agl-weston-waltham-remoting' as distro feature. + +``` + $ cd $AGL_TOP + $ source meta-agl/scripts/aglsetup.sh -f -b ${MACHINE_TYPE} [additional_distro_features] agl-weston-waltham-remoting +``` + +2. Build agl-demo-platform by using bitbake. + +3. Clone/download the waltham-transmitter-plugin on your own and build +locally using the build system provided. See README.md file for more +information. + +## How to configure weston.ini and GStreamer pipeline + +### weston.ini + +Add output name, host IP address, port number, and mode key under +'[transmitter-output]' section. +You can speficy multiple [transmitter-output] with different output-name. + +``` +/* Example_weston.ini - single transmitter-output */ + [transmitter-output] + name=transmitter-1 + mode=640x720@30 + host=192.168.20.99 + port=5005 + agl-shell-app-id=<APP_ID> +``` + +### GStreamer pipeline + +You can use GStreamer pipeline as you want. Here are some examples. + +``` + +/* General pipeline which does not use any HW encoder */ + appsrc name=src ! videoconvert ! video/x-raw,format=I420 ! jpegenc ! \ + rtpjpegpay ! udpsink name=sink host=YOUR_RECIEVER_IP \ + port=YOUR_RECIEVER_PORT sync=false async=false + +/* pipeline to use Intel's HW encoder */ + appsrc name=src ! videoconvert ! video/x-raw,format=I420 ! \ + mfxh264enc bitrate=3000000 rate-control=1 ! rtph264pay config-interval=1 ! \ + udpsink name=sink host=YOUR_RECIEVER_IP port=YOUR_RECIEVER_PORT \ + sync=false async=false + +/* pipeline to use Rcar's HW encoder */ + appsrc name=src ! videoconvert ! video/x-raw,format=I420 ! \ + omxh264enc bitrate=3000000 control-rate=2 ! rtph264pay ! \ + udpsink name=sink host=YOUR_RECIEVER_IP port=YOUR_RECIEVER_PORT \ + sync=false async=false + +``` + +## Connection Establishment + +1. Connect two boards over ethernet. +2. Assign IP to both boards. +```Example: + transmitter IP: 192.168.2.51 + waltham-receiver IP: 192.168.2.52 +``` +3. Check if the simple ping works +``` + $ ping 192.168.2.52 (you can also ping vice versa) +``` + +## Typical issues & Tips + +### help functions +You can find the help information of LayerManagerControl command by using + +``` +$ LayerManagerControl help +``` + +### waltham-transmitter and waltham-receiver doesn't not communicate + +1. Please check ethernet connection. If you assign 192.168.2.51 and + 192.168.2.52 for waltham-transmitter and waltham-receiver, you shall ping + vice versa. + +``` +/* At waltham-transmitter side */ + $ ping 192.168.2.52 + +/* At waltham-receiver side */ + $ ping 192.168.2.51 +``` + +2. Make sure that IP address specified in the weston.ini under + [transmitter-output] matches the waltham-receiver IP address. + +3. 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