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Ville Syrjälä 517e1355bb drm/i915: Also check for VGA converter in eDP probe

commit f76f83a83c8fdbb62acbf8bd945f10821768145b upstream.

Unfortunately even the HPD based detection added in
commit cfe5bdfb27 ("drm/i915: Check HPD live state during eDP probe")
fails to detect that the VBT's eDP/DDI-A is a ghost on
Asus B360M-A (CFL+CNP). On that board eDP/DDI-A has its HPD
asserted despite nothing being actually connected there :(
The straps/fuses also indicate that the eDP port is present.

So if one boots with a VGA monitor connected the eDP probe will
mistake the DP->VGA converter hooked to DDI-E for an eDP panel
on DDI-A.

As a last resort check what kind of DP device we've detected,
and if it looks like a DP->VGA converter then conclude that
the eDP port should be ignored.

Cc: stable@vger.kernel.org
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9636
Fixes: cfe5bdfb27 ("drm/i915: Check HPD live state during eDP probe")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231114142333.15799-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit fcd479a79120bf0cd507d85f898297a3b868dda6)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2023-12-08 08:52:16 +01:00