Add workaround for mir bug LP: #1656164

Workaround for black-screen on RPi3

5 files changed, 115 insertions, 0 deletions

diff --git a/drm-init-gamma/CMakeLists.txt b/drm-init-gamma/CMakeLists.txt
new file mode 100644
index 0000000..f096a58
--- /dev/null
+++ b/drm-init-gamma/CMakeLists.txt
@@ -0,0 +1,12 @@
+cmake_minimum_required (VERSION 3.0)
+project(drm-init-gamma)
+
+include (GNUInstallDirs)
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g -std=c++14")
+
+find_package(PkgConfig)
+pkg_check_modules(DRM REQUIRED libdrm)
+
+add_subdirectory(src)
diff --git a/drm-init-gamma/src/CMakeLists.txt b/drm-init-gamma/src/CMakeLists.txt
new file mode 100644
index 0000000..dcdc31d
--- /dev/null
+++ b/drm-init-gamma/src/CMakeLists.txt
@@ -0,0 +1,9 @@
+include_directories(${DRM_INCLUDE_DIRS})
+
+add_executable(drm-init-gamma drm-init-gamma.cpp)
+target_link_libraries(drm-init-gamma ${DRM_LDFLAGS} ${DRM_LIBRARIES})
+
+install(
+  TARGETS drm-init-gamma
+  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
+)
diff --git a/drm-init-gamma/src/drm-init-gamma.cpp b/drm-init-gamma/src/drm-init-gamma.cpp
new file mode 100644
index 0000000..6499711
--- /dev/null
+++ b/drm-init-gamma/src/drm-init-gamma.cpp
@@ -0,0 +1,83 @@
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+
+#include <cstdint>
+
+#include <algorithm>
+#include <limits>
+#include <iostream>
+#include <stdexcept>
+#include <vector>
+
+namespace
+{
+using GammaLUT = std::vector<uint16_t>;
+
+GammaLUT make_linear_ramp(uint32_t size)
+{
+    GammaLUT lut(size);
+    auto const step = std::numeric_limits<GammaLUT::value_type>::max() / (size - 1);
+    GammaLUT::value_type n = 0;
+    std::generate(lut.begin(), lut.end(), [&n, step]{ auto current = n; n += step; return current; });
+    return lut;
+}
+
+class DrmVersion
+{
+public:
+    DrmVersion(int fd) : ver(drmGetVersion(fd)) {}
+    ~DrmVersion() { drmFreeVersion(ver); }
+
+    drmVersionPtr operator->() { return ver; }
+private:
+    drmVersionPtr ver{nullptr};
+};
+
+class Drm
+{
+public:
+    Drm() : fd(open("/dev/dri/card0", O_RDWR | O_CLOEXEC))
+    {
+        if (fd < 1)
+            throw std::runtime_error("Could not open DRM device");
+        if (!is_vc4())
+            throw std::runtime_error("Not a VC4 drm device");
+    }
+    ~Drm() { close(fd); }
+
+    bool is_vc4()
+    {
+        DrmVersion info(fd);
+        return "vc4" == std::string(info->name);
+    }
+
+    void set_gamma()
+    {
+        uint32_t const size = 256;
+        uint32_t const crtc_id = 48;
+
+        GammaLUT lut = make_linear_ramp(size);
+        if (drmModeCrtcSetGamma(fd, crtc_id, size, &lut[0], &lut[0], &lut[0]) != 0)
+        {
+            throw std::runtime_error("failed to set Gamma LUT on drm device");
+        }
+    }
+private:
+    int fd;
+};
+}
+
+int main()
+try
+{
+    Drm drm;
+    drm.set_gamma();
+}
+catch (std::exception const& e)
+{
+    std::cerr << "error: " << e.what() << std::endl;
+}
diff --git a/run-miral b/run-miral
index d8432e1..e1b425a 100755
--- a/run-miral
+++ b/run-miral
@@ -32,6 +32,9 @@ export MIR_CLIENT_PLATFORM_PATH=$SNAP/mir-libs/$ARCH/mir/client-platform
 export MIR_SERVER_PLATFORM_PATH=$SNAP/mir-libs/$ARCH/mir/server-platform
 export LD_LIBRARY_PATH="$SNAP/mir-libs/$ARCH:$SNAP/mir-libs/$ARCH/mesa-egl:$LD_LIBRARY_PATH"
 
+# Workaround for mir bug LP:#1656164
+$SNAP/bin/drm-init-gamma
+
 while true; do
 
     bin_to_run=$(choose_kiosk_or_shell)
diff --git a/snapcraft.yaml b/snapcraft.yaml
index 1d3c8d0..07e6865 100644
--- a/snapcraft.yaml
+++ b/snapcraft.yaml
@@ -42,3 +42,11 @@ parts:
   inotify-tools:
     plugin: nil
     stage-packages: [inotify-tools]
+
+  drm-init-gamma:
+    plugin: cmake
+    source: drm-init-gamma
+    build-packages:
+      - build-essential
+      - libdrm-dev
+      - pkg-config