[PATCH 2/6] drm/i915: Don't wait for page flips if there was GPU reset

[ville.syrjala@linux.intel.com]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

If a GPU reset occurs while a page flip has been submitted to the ring,
the flip will never complete once the ring has been reset.

The GPU reset can be detected by sampling the reset_counter before the
flip is submitted, and then while waiting for the flip, the sampled
counter is compared with the current reset_counter value.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 14 +++++++++++++-
 drivers/gpu/drm/i915/intel_drv.h     |  3 +++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4097118..e348a68 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2862,10 +2862,12 @@ static bool intel_crtc_has_pending_flip(struct drm_crtc *crtc)
 {
 	struct drm_device *dev = crtc->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	unsigned long flags;
 	bool pending;
 
-	if (i915_reset_in_progress(&dev_priv->gpu_error))
+	if (i915_reset_in_progress(&dev_priv->gpu_error) ||
+	    intel_crtc->reset_counter != atomic_read(&dev_priv->gpu_error.reset_counter))
 		return false;
 
 	spin_lock_irqsave(&dev->event_lock, flags);
@@ -6912,6 +6914,8 @@ static int intel_gen2_queue_flip(struct drm_device *dev,
 	if (ret)
 		goto err_unpin;
 
+	intel_crtc->reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
+
 	/* Can't queue multiple flips, so wait for the previous
 	 * one to finish before executing the next.
 	 */
@@ -6956,6 +6960,8 @@ static int intel_gen3_queue_flip(struct drm_device *dev,
 	if (ret)
 		goto err_unpin;
 
+	intel_crtc->reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
+
 	if (intel_crtc->plane)
 		flip_mask = MI_WAIT_FOR_PLANE_B_FLIP;
 	else
@@ -6997,6 +7003,8 @@ static int intel_gen4_queue_flip(struct drm_device *dev,
 	if (ret)
 		goto err_unpin;
 
+	intel_crtc->reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
+
 	/* i965+ uses the linear or tiled offsets from the
 	 * Display Registers (which do not change across a page-flip)
 	 * so we need only reprogram the base address.
@@ -7045,6 +7053,8 @@ static int intel_gen6_queue_flip(struct drm_device *dev,
 	if (ret)
 		goto err_unpin;
 
+	intel_crtc->reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
+
 	intel_ring_emit(ring, MI_DISPLAY_FLIP |
 			MI_DISPLAY_FLIP_PLANE(intel_crtc->plane));
 	intel_ring_emit(ring, fb->pitches[0] | obj->tiling_mode);
@@ -7111,6 +7121,8 @@ static int intel_gen7_queue_flip(struct drm_device *dev,
 	if (ret)
 		goto err_unpin;
 
+	intel_crtc->reset_counter = atomic_read(&dev_priv->gpu_error.reset_counter);
+
 	intel_ring_emit(ring, MI_DISPLAY_FLIP_I915 | plane_bit);
 	intel_ring_emit(ring, (fb->pitches[0] | obj->tiling_mode));
 	intel_ring_emit(ring, obj->gtt_offset + intel_crtc->dspaddr_offset);
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index fcdfe42..a5521d9 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -235,6 +235,9 @@ struct intel_crtc {
 	/* We can share PLLs across outputs if the timings match */
 	struct intel_pch_pll *pch_pll;
 	uint32_t ddi_pll_sel;
+
+	/* reset counter value when the last flip was submitted */
+	unsigned int reset_counter;
 };
 
 struct intel_plane {
-- 
1.7.12.4

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