[PATCH 4/5] drm/i915/bxt: Block D3 during suspend.

[Animesh Manna]

For BXT, display engine can not generate interrupt when in D3.
On the othen hand S0ix can be achieved without display in D3. So,
Display should not put into D3 for HPD to work and will not
have any power impact.

v1: Initial version as RFC.

v2: Based on review comment from David,
condition check for hpd_wakeup_enabled is removed before
calling pci_restore_state.

Signed-off-by: Animesh Manna <animesh.manna at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 7a925c5..0c55ce53 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -2448,6 +2448,9 @@ static int intel_runtime_suspend(struct device *kdev)
 	if (!IS_VALLEYVIEW(dev_priv) && !IS_CHERRYVIEW(dev_priv))
 		intel_hpd_poll_init(dev_priv);
 
+	if (dev_priv->vbt.hpd_wakeup_enabled)
+		pci_save_state(pdev);
+
 	DRM_DEBUG_KMS("Device suspended\n");
 	return 0;
 }
@@ -2464,6 +2467,8 @@ static int intel_runtime_resume(struct device *kdev)
 
 	DRM_DEBUG_KMS("Resuming device\n");
 
+	pci_restore_state(pdev);
+
 	WARN_ON_ONCE(atomic_read(&dev_priv->pm.wakeref_count));
 	disable_rpm_wakeref_asserts(dev_priv);
 
-- 
1.9.1