[3.11.y.z extended stable] Patch "drm/i915: Use the correct GMCH_CTRL register for Sandybridge+" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    drm/i915: Use the correct GMCH_CTRL register for Sandybridge+

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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>From a43aa3f7c947f555f2032eb283ba94e6fa66555c Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris at chris-wilson.co.uk>
Date: Tue, 17 Dec 2013 14:34:50 +0000
Subject: drm/i915: Use the correct GMCH_CTRL register for Sandybridge+
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit a885b3ccc74d8e38074e1c43a47c354c5ea0b01e upstream.

The GMCH_CTRL register (or MGCC in the spec) is at a different address
on Sandybridge, and the address to which we currently write to is
undefined. These stray writes appear to upset (hard hang) my Ivybridge
machine whilst it is in UEFI mode.

Note that the register is still marked as locked RO on Sandybridge, so
vgaarb is still dysfunctional.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula at intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/gpu/drm/i915/intel_display.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index ee0b38f..cfe124a 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -10072,14 +10072,15 @@ void intel_connector_attach_encoder(struct intel_connector *connector,
 int intel_modeset_vga_set_state(struct drm_device *dev, bool state)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	unsigned reg = INTEL_INFO(dev)->gen >= 6 ? SNB_GMCH_CTRL : INTEL_GMCH_CTRL;
 	u16 gmch_ctrl;

-	pci_read_config_word(dev_priv->bridge_dev, INTEL_GMCH_CTRL, &gmch_ctrl);
+	pci_read_config_word(dev_priv->bridge_dev, reg, &gmch_ctrl);
 	if (state)
 		gmch_ctrl &= ~INTEL_GMCH_VGA_DISABLE;
 	else
 		gmch_ctrl |= INTEL_GMCH_VGA_DISABLE;
-	pci_write_config_word(dev_priv->bridge_dev, INTEL_GMCH_CTRL, gmch_ctrl);
+	pci_write_config_word(dev_priv->bridge_dev, reg, gmch_ctrl);
 	return 0;
 }

--
1.8.3.2