[Intel-gfx] [PATCH] drm/i915/bxt: Save/restore HOTPLUG_CTL during suspend/resume.

[Matt Roper]

From: Bob Paauwe <bob.j.paauwe at intel.com>

Broxton has some additional bits in the HOTPLUG_CTL register that
indicate whether the HPD sense lines need to be inverted or not for the
current platform.  The BIOS sets these bits to an appropriate value at
boot time, but the value is lost across suspend/resume.  We need to save
and restore the register so that hotplug and display detect works on
resume.

Signed-off-by: Bob Paauwe <bob.j.paauwe at intel.com>
[mattrope: Expand commit message]
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h     | 1 +
 drivers/gpu/drm/i915/i915_suspend.c | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 77227a3..2278117 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1061,6 +1061,7 @@ struct i915_suspend_saved_registers {
 	uint64_t saveFENCE[I915_MAX_NUM_FENCES];
 	u32 savePCH_PORT_HOTPLUG;
 	u16 saveGCDGMBUS;
+	u32 saveHOTPLUG;
 };
 
 struct vlv_s0ix_state {
diff --git a/drivers/gpu/drm/i915/i915_suspend.c b/drivers/gpu/drm/i915/i915_suspend.c
index 34e061a..efe1e77 100644
--- a/drivers/gpu/drm/i915/i915_suspend.c
+++ b/drivers/gpu/drm/i915/i915_suspend.c
@@ -59,6 +59,10 @@ static void i915_save_display(struct drm_device *dev)
 	/* save FBC interval */
 	if (HAS_FBC(dev) && INTEL_INFO(dev)->gen <= 4 && !IS_G4X(dev))
 		dev_priv->regfile.saveFBC_CONTROL = I915_READ(FBC_CONTROL);
+
+	if (IS_BROXTON(dev))
+		dev_priv->regfile.saveHOTPLUG = I915_READ(PCH_PORT_HOTPLUG);
+
 }
 
 static void i915_restore_display(struct drm_device *dev)
@@ -98,6 +102,9 @@ static void i915_restore_display(struct drm_device *dev)
 	if (HAS_FBC(dev) && INTEL_INFO(dev)->gen <= 4 && !IS_G4X(dev))
 		I915_WRITE(FBC_CONTROL, dev_priv->regfile.saveFBC_CONTROL);
 
+	if (IS_BROXTON(dev))
+		I915_WRITE(PCH_PORT_HOTPLUG, dev_priv->regfile.saveHOTPLUG);
+
 	i915_redisable_vga(dev);
 }
 
-- 
2.1.4