Daniel Vetter aaa377302b drm/i915/crt: Do not rely upon the HPD presence pin ... VGA hotplug detection "works" by measuring the resistance across certain pins. A lot of kvm switches fumble this and wire up cheap resistors with the wrong resistance or don't bother at all. To accomodate these, also try to detect a connected monitor by trying to grab the edid. Contrary to !HAS_HOTPLUG platforms we don't bother with an actual load-detection cycle when the output is life - that would be actual work to implement because things moved around. This is the big difference to Chris Wilson's original approach: commit 9e612a008f Author: Chris Wilson <chris@chris-wilson.co.uk> Date: Thu May 31 13:08:53 2012 +0100 drm/i915/crt: Do not rely upon the HPD presence pin This blew up on Linus' machine because it errornously detected a vga screen (without and edid and hence only the default modes), leading to it's prompt removal: commit 8f53369b75 Author: Linus Torvalds <torvalds@linux-foundation.org> Date: Fri Jun 8 14:53:06 2012 -0700 Revert "drm/i915/crt: Do not rely upon the HPD presence pin" Some digging around in Bspec shows the reason why load detect doesn't work on newer chips - the legacy VGA load detect bit isn't wired up any longer: Public Snb Bspec, Vol3 Part1, 1.1.1 ST00 Input Status 0, bit4: "RGB Comparator / Sense. This bit is here for compatibility and will always return one. Monitor detection must be done be done through the programming of registers in the MMIO space. 0 = Below threshold 1 = Above threshold" v2: Add a comment in the code that load detect on hotplug capable machines is broken and pimp the commit message with a quote of Bspec to show why. Reported-and-tested-by: Matthieu LAVIE <boiteamadmax@hotmail.com> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=50501 Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>		2012-06-16 15:30:32 +02:00
..
drm	drm/i915/crt: Do not rely upon the HPD presence pin	2012-06-16 15:30:32 +02:00
stub	i915: select VIDEO_OUTPUT_CONTROL for ACPI_VIDEO	2011-04-13 09:10:25 +10:00
vga	vga_switcheroo: Add the support for audio clients	2012-05-13 11:27:21 +02:00
Makefile	gpu: Add Intel GMA500(Poulsbo) Stub Driver	2010-10-26 11:00:13 +10:00