Touching the VGA registers risks a hard machine hang, at least on this
ivb machine after removing a conflicting efifb. This is more than likely
related to the discovery that VGA IO decode on the more recent PCH
platforms is terminally broken.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
drivers/gpu/drm/i915/intel_display.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_display.c
b/drivers/gpu/drm/i915/intel_display.c
index 7db292c469af..d9b91a585dbf 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11341,6 +11341,9 @@ int intel_modeset_vga_set_state(struct drm_device *dev,
bool state)
return -EIO;
}
+ if (!!(gmch_ctrl & INTEL_GMCH_VGA_DISABLE) == !state)
+ return 0;
+
if (state)
gmch_ctrl &= ~INTEL_GMCH_VGA_DISABLE;
else
--
1.8.5.1
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