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Runtime display selection in DRM backend #2197

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e801dd3
gamescope-control: Introduce display_selection interface for output s…
matte-schwartz May 22, 2026
caf65b4
DRMBackend: further disambiguate identical displays by MST path
matte-schwartz May 25, 2026
31aa513
xprops: hook up atoms for display selection
matte-schwartz May 25, 2026
d85e510
[HACK] DRMBackend: Temporarily write preferred-display file on set_di…
matte-schwartz May 22, 2026
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26 changes: 25 additions & 1 deletion protocol/gamescope-control.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,7 @@
it.
</description>

<interface name="gamescope_control" version="6">
<interface name="gamescope_control" version="7">
<request name="destroy" type="destructor"></request>

<enum name="feature">
Expand All @@ -44,6 +44,7 @@
<entry name="mura_correction" value="5"/>
<entry name="look" value="6"/>
<entry name="perf_query" value="7"/>
<entry name="display_selection" value="8"/>
</enum>

<event name="feature_support">
Expand All @@ -59,6 +60,7 @@
<entry name="internal_display" value="0x1"/>
<entry name="supports_hdr" value="0x2"/>
<entry name="supports_vrr" value="0x4"/>
<entry name="current" value="0x8"/>
</enum>

<event name="active_display_info" since="2">
Expand Down Expand Up @@ -143,5 +145,27 @@
<arg name="frametime_ns_hi" type="uint" summary="frametime_ns high bits"></arg>
</event>

<event name="available_display_info" since="7">
<description summary="report one display the compositor can switch to"></description>
<arg name="connector_name" type="string" summary="connector name (e.g. 'DP-1') to pass back via set_display"/>
<arg name="display_make" type="string"/>
<arg name="display_model" type="string"/>
<arg name="display_flags" type="uint" enum="display_flag" summary="combination of 'display_flag' values"/>
<arg name="display_identifier" type="string" summary="opaque EDID-derived key for persisting a display preference; identical monitors get a trailing ' [...]' suffix to disambiguate, so match identity on the text before it, then set_display its connector_name"/>
</event>

<event name="available_display_info_done" since="7">
<description summary="terminator for an available_display_info batch"></description>
</event>

<request name="set_display" since="7">
<description summary="select the display to drive; ignored if connector_name is not a currently-connected output"></description>
<arg name="connector_name" type="string" summary="connector to drive, as reported by available_display_info"/>
</request>

<request name="unset_display" since="7">
<description summary="clear any runtime display selection"></description>
</request>

</interface>
</protocol>
57 changes: 53 additions & 4 deletions src/Apps/gamescopectl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,15 @@ namespace gamescope
std::vector<uint32_t> ValidRefreshRates;
};

struct GamescopeAvailableDisplayInfo
{
std::string szConnectorName;
std::string szDisplayMake;
std::string szDisplayModel;
uint32_t uDisplayFlags;
std::string szDisplayIdentifier;
};

class GamescopeCtl
{
public:
Expand All @@ -44,6 +53,7 @@ namespace gamescope

std::span<GamescopeFeature> GetFeatures() { return std::span<GamescopeFeature>{ m_Features }; }
const std::optional<GamescopeActiveDisplayInfo> &GetActiveDisplayInfo() { return m_ActiveDisplayInfo; }
std::span<const GamescopeAvailableDisplayInfo> GetAvailableDisplays() { return m_AvailableDisplays; }
private:
bool m_bInitControl = false;
bool m_bInitPrivate = false;
Expand All @@ -56,13 +66,15 @@ namespace gamescope

std::vector<GamescopeFeature> m_Features;
std::optional<GamescopeActiveDisplayInfo> m_ActiveDisplayInfo;
std::vector<GamescopeAvailableDisplayInfo> m_AvailableDisplays;

void Wayland_Registry_Global( wl_registry *pRegistry, uint32_t uName, const char *pInterface, uint32_t uVersion );
static const wl_registry_listener s_RegistryListener;

void Wayland_GamescopeControl_FeatureSupport( gamescope_control *pGamescopeControl, uint32_t uFeature, uint32_t uVersion, uint32_t uFlags );
void Wayland_GamescopeControl_ActiveDisplayInfo( gamescope_control *pGamescopeControl, const char *pConnectorName, const char *pDisplayMake, const char *pDisplayModel, uint32_t uDisplayFlags, wl_array *pValidRefreshRatesArray );
void Wayland_GamescopeControl_ScreenshotTaken( gamescope_control *pGamescopeControl, const char *pPath );
void Wayland_GamescopeControl_AvailableDisplayInfo( gamescope_control *pGamescopeControl, const char *pConnectorName, const char *pDisplayMake, const char *pDisplayModel, uint32_t uDisplayFlags, const char *pDisplayIdentifier );
static const gamescope_control_listener s_GamescopeControlListener;

void Wayland_GamescopePrivate_Log( gamescope_private *pGamescopePrivate, const char *pText );
Expand Down Expand Up @@ -187,12 +199,26 @@ namespace gamescope
fprintf( stderr, "Screenshot taken to: %s\n", pPath );
}

void GamescopeCtl::Wayland_GamescopeControl_AvailableDisplayInfo( gamescope_control *pGamescopeControl, const char *pConnectorName, const char *pDisplayMake, const char *pDisplayModel, uint32_t uDisplayFlags, const char *pDisplayIdentifier )
{
m_AvailableDisplays.emplace_back( GamescopeAvailableDisplayInfo
{
.szConnectorName = pConnectorName,
.szDisplayMake = pDisplayMake,
.szDisplayModel = pDisplayModel,
.uDisplayFlags = uDisplayFlags,
.szDisplayIdentifier = pDisplayIdentifier,
} );
}

const gamescope_control_listener GamescopeCtl::s_GamescopeControlListener =
{
.feature_support = WAYLAND_USERDATA_TO_THIS( GamescopeCtl, Wayland_GamescopeControl_FeatureSupport ),
.active_display_info = WAYLAND_USERDATA_TO_THIS( GamescopeCtl, Wayland_GamescopeControl_ActiveDisplayInfo ),
.screenshot_taken = WAYLAND_USERDATA_TO_THIS( GamescopeCtl, Wayland_GamescopeControl_ScreenshotTaken ),
.app_performance_stats = WAYLAND_NULL(),
.feature_support = WAYLAND_USERDATA_TO_THIS( GamescopeCtl, Wayland_GamescopeControl_FeatureSupport ),
.active_display_info = WAYLAND_USERDATA_TO_THIS( GamescopeCtl, Wayland_GamescopeControl_ActiveDisplayInfo ),
.screenshot_taken = WAYLAND_USERDATA_TO_THIS( GamescopeCtl, Wayland_GamescopeControl_ScreenshotTaken ),
.app_performance_stats = WAYLAND_NULL(),
.available_display_info = WAYLAND_USERDATA_TO_THIS( GamescopeCtl, Wayland_GamescopeControl_AvailableDisplayInfo ),
.available_display_info_done = WAYLAND_NULL(),
};

void GamescopeCtl::Wayland_GamescopePrivate_Log( gamescope_private *pGamescopePrivate, const char *pText )
Expand Down Expand Up @@ -231,6 +257,8 @@ namespace gamescope
return "Look";
case GAMESCOPE_CONTROL_FEATURE_PERF_QUERY:
return "Performance Query";
case GAMESCOPE_CONTROL_FEATURE_DISPLAY_SELECTION:
return "Display Selection";
default:
return "Unknown";
}
Expand Down Expand Up @@ -266,6 +294,27 @@ namespace gamescope
}
fprintf( stdout, "\n" );
}
auto availableDisplays = gamescopeCtl.GetAvailableDisplays();
if ( !availableDisplays.empty() )
{
fprintf( stdout, " Available Displays:\n" );
for ( const GamescopeAvailableDisplayInfo &avail : availableDisplays )
{
fprintf( stdout, " - %s", avail.szConnectorName.c_str() );
std::string szMakeModel = avail.szDisplayMake;
if ( !szMakeModel.empty() && !avail.szDisplayModel.empty() )
szMakeModel += " ";
szMakeModel += avail.szDisplayModel;
if ( !szMakeModel.empty() )
fprintf( stdout, " (%s)", szMakeModel.c_str() );
fprintf( stdout, " - Flags: 0x%x", avail.uDisplayFlags );
if ( !avail.szDisplayIdentifier.empty() )
fprintf( stdout, " - Identifier: \"%s\"", avail.szDisplayIdentifier.c_str() );
if ( avail.uDisplayFlags & GAMESCOPE_CONTROL_DISPLAY_FLAG_CURRENT )
fprintf( stdout, " [current]" );
fprintf( stdout, "\n" );
}
}
fprintf( stdout, " Features:\n" );
for ( const GamescopeFeature &feature : gamescopeCtl.GetFeatures() )
{
Expand Down
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