PhosphorIdentity::ScreenId Namespace Reference

Compositor-agnostic EDID parsing and screen-ID construction. More...

Namespaces
namespace	detail

Functions
QString	readEdidHeaderSerial (const QString &connectorName)
	Read the EDID header serial from sysfs for a DRM connector.
void	invalidateEdidCache (const QString &connectorName=QString())
	Drop cached EDID serial data.
QString	normalizeHexSerial (const QString &serial)
	Coerce a possibly-hex serial ("0x0001C1A3") to decimal ("115107").
QString	buildBaseId (const QString &manufacturer, const QString &model, const QString &serial)
	Assemble a base identifier from EDID-style fields.
QString	buildScreenBaseId (const QString &manufacturer, const QString &model, const QString &serialNumber, const QString &connectorName)
	Build a base ID from raw EDID fields with sysfs serial fallback.

Detailed Description

Compositor-agnostic EDID parsing and screen-ID construction.

Owns the canonical "manufacturer:model:serial" wire format used by every Phosphor consumer that refers to a physical screen across processes. Daemon (via QScreen properties) and compositor plugins (via wlr_output / KWin::Output) feed in their own raw fields and get back byte-identical IDs.

EDID header format (VESA E-EDID 1.3+, sysfs blob /sys/class/drm/.../edid): Bytes 0-7 : magic header (00 FF FF FF FF FF FF 00) Bytes 8-9 : manufacturer ID Bytes 10-11 : product code Bytes 12-15 : serial number (little-endian uint32)

Threading: the sysfs cache is accessed without synchronisation; every function MUST be called from the GUI / main thread.

Function Documentation

buildBaseId()

QString PhosphorIdentity::ScreenId::buildBaseId ( const QString &  manufacturer, const QString &  model, const QString &  serial  )

inline

Assemble a base identifier from EDID-style fields.

"manuf:model:serial" when serial is available, "manuf:model" when only those are present, empty when no field is set (caller should fall back to the connector name).

buildScreenBaseId()

QString PhosphorIdentity::ScreenId::buildScreenBaseId ( const QString &  manufacturer, const QString &  model, const QString &  serialNumber, const QString &  connectorName  )

inline

Build a base ID from raw EDID fields with sysfs serial fallback.

Tries serialNumber (after normalizeHexSerial) first, then sysfs. Returns the connector name as a final fallback so the result is always a non-empty stable string.

invalidateEdidCache()

void PhosphorIdentity::ScreenId::invalidateEdidCache ( const QString &  connectorName = QString() )

inline

Drop cached EDID serial data.

Call on hotplug; pass an empty string to drop everything.

normalizeHexSerial()

QString PhosphorIdentity::ScreenId::normalizeHexSerial ( const QString &  serial )

inline

Coerce a possibly-hex serial ("0x0001C1A3") to decimal ("115107").

KWin on Wayland exposes the EDID header serial as hex via QScreen::serialNumber(). Both daemon and compositor must produce byte-identical IDs, so we normalise to decimal.

readEdidHeaderSerial()

QString PhosphorIdentity::ScreenId::readEdidHeaderSerial ( const QString &  connectorName )

inline

Read the EDID header serial from sysfs for a DRM connector.

Scans /sys/class/drm/card*-<connectorName>/edid, validates the EDID magic header, and extracts the serial number from bytes 12-15 (little-endian uint32, decimal-formatted).

Cached after the first successful read. After 3 consecutive misses the empty result is cached permanently to avoid unbounded sysfs I/O for virtual displays / embedded panels. Use invalidateEdidCache on hotplug.