diff mbox

[0177/1094] drm/i915: Short-circuit no-op vga_set_state()

Message ID 1413889294-31328-178-git-send-email-dheerajx.s.jamwal@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Dheeraj Jamwal Oct. 21, 2014, 10:46 a.m. UTC 
From: Chris Wilson <chris@chris-wilson.co.uk>

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 <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit c0cc8a556680afbfc6dc5033bdf9c8d2b85088e2)

Signed-off-by: Dheeraj Jamwal <dheerajx.s.jamwal@intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |    3 +++
 1 file changed, 3 insertions(+)
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 7b88eb2..fa09a3c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11527,6 +11527,9 @@  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