Comment 57 for bug 22985

I am posting a revision of the patch - see the attached. With this patch you
will see the following improvements - you will be able to

(1) Start X server without a config file, with or without CRT connected.

    * Without CRT, you will get a native LCD resolution 1680x1050.
    * With CRT connected, you will get a resolution that is the largest
      common mode supported by both LCD and CRT monitor, which could be
      lower than LCD's native resolution.

(2) Connect external CRT to a system previously booted without external
    CRT connected.

    If you first boot machine without CRT connected, later decide to
    connect CRT - you can do it without rebooting, only a server restart
    will turn on display of the CRT monitor.

Featrue (2) is added in this revision:

When a laptop is booted without CRT connected, BIOS powers down DAC
of VGA port to save power. This results in

    * Wrong resutls from CRT connection testing
      (RADEONCrtIsPhysicallyConnected()) because testing needs to
      read/write DAC registers.
    * Failure in connecting external CRT later, there is no or very dim display
      on monitor screen.

    The new patch solves the problem by following this sequence:

    * If DAC is detected powered down, power it up before doing
      CRT connection testing.
    * If testing result shows CRT is connected, keep DAC power up,
      otherwise power DAC down again.
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