[Bug 63031] New: [Intel GM45][i915-kms]: VGA encoder on SDVOB remains blank when i915.ko is loaded while gfx is in text mode.

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=63031

          Priority: medium
            Bug ID: 63031
          Assignee: intel-gfx-bugs at lists.freedesktop.org
           Summary: [Intel GM45][i915-kms]: VGA encoder on SDVOB remains
                    blank when i915.ko is loaded while gfx is in text
                    mode.
        QA Contact: intel-gfx-bugs at lists.freedesktop.org
          Severity: normal
    Classification: Unclassified
                OS: All
          Reporter: eich at pdx.freedesktop.org
          Hardware: x86-64 (AMD64)
            Status: NEW
           Version: XOrg CVS
         Component: DRM/Intel
           Product: DRI

With any latest Intel DRM kernels the VGA output on SDVOB remains dark when a
VGA text mode was set prior to loading the i915 driver. 
When a VBE gfx mode was loaded, the system comes up fine.

Here is what happens:
When the driver loads intel_modeset_setup_hw_state() is called at one point to
collect the current state of the hardware setting. 
At one point, this function calls into intel_sdvo_get_hw_state() to check if
bit 32 of register GEN3_SDVOB. If this bit is 0 the function returns 'false'
indicating there is no active pipe connected to this encoder.
intel_modeset_setup_hw_state() then calls intel_sanitize_encoder() which will
call intel_connector_break_all_links() in this situation. 
At a later point intel_connector_check_state() will complain heavily.
As a result SDVOB will be treated as disabled and unconnected during the entire
mode setting.

Setting bit 31 of GEN3_SDVOB at any point before intel_modeset_setup_hw_state()
is called will cause the driver to correctly initialize the SDVOB.
Also setting a VBE gfx mode prior to loading the driver will set this bit and
thus the DAC encoder on SDVOB will be initialized correctly.

Thus the kernel is misled by a bogus mode set by the BIOS,

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