eglfs/kms: hot-plug and hot-reloadHEADdev

This patch extends eglfs/kms to react to events during runtime:
 - screens/displays getting connected ("plug in")
   as well as disconnected ("unplug")
   This is only enabled when setting QT_QPA_EGLFS_HOTPLUG_ENABLED
 - changes to the kms-config-file referenced by QT_QPA_EGLFS_KMS_CONFIG or QT_QPA_KMS_CONFIG

eglfs will now reevaluate the connected displays and the referenced
kms-config during runtime and react accordingly.

Features/functionality of hot-plug:
 - QKmsDevice::checkConnectedScreens() (new function)
   will be called by QDeviceDiscovery::deviceChanged (new signal),
   which is fired by QDeviceDiscoveryUDev::handleUDevNotification
   when "change"(formerly ignored) is the action driven/created by udev

   - disconnected screens will be unregistered via
     QKmsDevice::unregisterScreen
     (new virtual function, this variant is empty).

     The code lives in the two implementations of unregisterScreen:
     QEglFSKmsGbmDevice::unregisterScreen will deal with global-cursor,
     then call it's parent variant QEglFSKmsDevice::unregisterScreen
     to call QWindowSystemInterface::handleScreenRemoved,
     feeding the information about the lost screen into the event loop

   - each newly connected display will be "configured" via
     QKmsDevice::createScreenInfoForConnector (refactored function),
     and then the platform class will be created via
     QKmsDevice::createScreen

Features/functionality of hot-reload:
 - refactor QKmsDevice::createScreenForConnector to
   QKmsDevice::createScreenInfoForConnector, as the hot-reload requires
   to update QPlatformScreens rather then creating new ones right away

 - QFileSystemWatcher is added to QEglFSKmsGbmIntegration in
   QEglFSKmsGbmIntegration::createDevice()
   It will watch the file referenced by
   QT_QPA_EGLFS_KMS_CONFIG or QT_QPA_KMS_CONFIG

   When QFileSystemWatcher::fileChanged is fired,
   two function will be called:
   - KmsScreenConfig::refreshConfig(),
     a new function which clears the old config and calls
     QKmsScreenConfig::loadConfig()
   - QKmsDevice::updateScreens(), a new function that goes over all
     plugged-in and enabled screens, recreates their configuration via
     QKmsDevice::createScreenInfoForConnector, updates them via
     QKmsDevice/QEglFSKmsDevice::updateScreenOutput (new virtual),
     and at the end will call QKmsDevice::registerScreens
     (new function, see "shared changes" for details)

Shared changes / necessary refactoring:
 - QKmsDevice::createScreens was refactored and split, where
   QKmsDevice::registerScreens contains code regarding screen-cloning,
   calling QKmsDevice::registerScreen (existing, pure virtual) and
   calling QKmsDevice::updateScreen (new, virtual function with one
   "proper" implementation in QEglFSKmsDevice::updateScreen)

 - Adding code regarding creation and destruction of qt_headless
   A replacement screen is needed when going to 0 displays,
   as that is not supported by Qt.
   This applies to all 3 cases: startup, hotplug and hotreload
   (while for 'startup' it will only create a headless screen if
    QT_QPA_EGLFS_HOTPLUG_ENABLED is set)

 - added "headlessSize" to kms-config to allow the user to configure
   the specific size of the headless "fake" screen
 - default value for "headlessSize" is 1024x768 (used to be 0x0)
   Those two changes are necessary/useful as headless
   is an implicit feature in this case as the fallback
   for when the last screen is disconnected.
   (In contrast to explicit 'headless' option)

 - a bunch of extra code regarding cloned screens,
   because they can now be added and removed during runtime
   (via screen-plug-in/out events as well as config changes)

 - renaming m_nonThreadedFlipMutex to s_nonThreadedFlipMutex
   as it's a static member

 - fix virtualPos to allow for 0,0 to be a valid setting
   (by having -1,-1 as 'is not set'-value)

 - QKmsDevice::registerScreens will now check if the cursor is
   outside the current desktopRegion. If it is, it will be
   repositioned to be inside (it would vanish otherwise)

- adding wait-timout in waitForFlipWithEventReader
  to account for the fact that cloned screens can be created
  and added during the runtime.
  Without a timeout it can happen that the clonee waits forever,
  as the new clone can be added as a flip-dependency
  while it isn't scheduled to wake the clonee's wait yet

Change-Id: I08421a1be156b6edb9906ef736cba149dab360ff
Reviewed-by: Laszlo Agocs <[email protected]>

0 files changed, 0 insertions, 0 deletions