web_Display_detect_oper

Display Detect Operation

This section describes the logic of the Display Detection feature and provides several examples.

1. If Display Detect is disabled, the driver uses the first two ports identified in the PortOrder.

2. If Display Detect is enabled and you are using the 1.6 version of the VBIOS, the VBIOS performs the display detection. The driver then checks whether the VBIOS returns the display allocations and if it does, the driver does not re-execute the display detection steps.

If you are not using the EMGD-developed VBIOS, then the driver performs display discovery as described in the following steps.

3. The number of displays to be detected is based on the DisplayConfig settings in the configuration. If this is set to Single, then only one display is detected. If it is set to any other value, a maximum of two displays will be detected.

4. The Intel® EMGD goes through each port in the PortOrder settings and attempts to detect a display using the following algorithm:

a. PortOrder sequence determines display detection. Port allocation shows after the display has been detected. For example:

PortOrder = “42000” (LVDS, SDVO)

Displays Connected = LVDS

Primary display allocation: Searches for a display connected according to the PortOrder sequence. The first detected display is an LVDS, so the Primary display is “LVDS.”

Secondary display allocation: Searches for a display connected according to the PortOrder sequence. The first non-allocated display detected is SDVO, so the Secondary display is “SDVO.”

b. With no display detected on any port, then turn off the DisplayDetect option and allocate ports in the order defined by PortOrder. For example:

PortOrder = “20000”

Displays Connected = None

Primary display allocation: Searches for a connected display according to the PortOrder. Because Intel® EMGD detects no displays, the Primary display is set to “SDVO-B.”

c. The driver cannot detect the presence of a display connected to the Internal LVDS and external LVDS displays connected to some SDVO devices, for example, an LVDS connected to the CH7308. Consequently, the driver assumes that an LVDS display is connected if it is in the PortOrder. If you only want to use the internal LVDS when no external panel (from SDVO) or devices are connected, then put LVDS in the PortOrder after them. For example:

PortOrder = “24000” (SDVOB, LVDS)

Display Connected = None

Primary display allocation: Searches for a display connected according to PortOrder sequence. Since no display is connected and since LVDS is specified in the PortOrder, the driver assumes that an LVDS display is connected. Consequently, set the Primary display to “LVDS.”

d. When the port drivers do not load for any ports specified in the PortOrder, the driver enables port 4 (LVDS) only. For example:

PortOrder = “20000” (SDVO)

PortDrivers = “” (None)

Primary display allocation: Searches for displays connected according to the PortOrder. Since no port drivers are available for the specified ports, LVDS port 4 is enabled. Consequently, set the Primary display to “LVDS.”




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Revised June 20, 2011