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[5/9] drm/i915: Short-circuit no-op vga_set_state()

Message ID 1391805427-4576-6-git-send-email-rodrigo.vivi@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Rodrigo Vivi Feb. 7, 2014, 8:37 p.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>
---
 drivers/gpu/drm/i915/intel_display.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Daniel Vetter Feb. 10, 2014, 10:36 a.m. UTC | #1 
On Fri, Feb 07, 2014 at 06:37:03PM -0200, Rodrigo Vivi wrote:
> 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>

Queued for -next, thanks for the patch.
-Daniel
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 1e9dd84..c411bf8 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11575,6 +11575,9 @@  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