[Intel-gfx] [PATCH 3/3] drm/i915: don't rewrite the GTT on resume v2

[Jesse Barnes]

The BIOS shouldn't be touching this memory across suspend/resume, so
just leave it alone.  This saves us ~50ms on resume on my T420.

v2: change gtt restore default on pre-gen4 (Chris)
    move needs_gtt_restore flag into dev_priv

Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
---
 drivers/gpu/drm/i915/i915_dma.c |    4 ++++
 drivers/gpu/drm/i915/i915_drv.c |    3 ++-
 drivers/gpu/drm/i915/i915_drv.h |    2 ++
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index b5977b4..c027266 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1339,6 +1339,10 @@ static int i915_load_modeset_init(struct drm_device *dev)
 	/* FIXME: do pre/post-mode set stuff in core KMS code */
 	dev->vblank_disable_allowed = 1;
 
+	/* Gen4+ should have saner BIOSes (we hope) */
+	if (INTEL_INFO(dev)->gen < 4)
+		dev_priv->needs_gtt_restore = true;
+
 	ret = intel_fbdev_init(dev);
 	if (ret)
 		goto cleanup_irq;
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 4d858a9..be9f47d 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -540,7 +540,8 @@ static int i915_drm_thaw(struct drm_device *dev)
 
 	intel_gt_reset(dev);
 
-	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
+	if (drm_core_check_feature(dev, DRIVER_MODESET) &&
+	    dev_priv->needs_gtt_restore) {
 		mutex_lock(&dev->struct_mutex);
 		i915_gem_restore_gtt_mappings(dev);
 		mutex_unlock(&dev->struct_mutex);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 1e84a59..a38eba8 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -873,6 +873,8 @@ typedef struct drm_i915_private {
 
 	struct delayed_work gen6_power_work;
 
+	bool needs_gtt_restore;
+
 	enum no_fbc_reason no_fbc_reason;
 
 	struct drm_mm_node *compressed_fb;
-- 
1.7.9.5