[PATCH 2/3] drm/i915: Enable FIFO underrun reporting after initial fastset

[Maarten Lankhorst]

The firmware may have set up the pipe correctly, but the FIFO
underrun and CRC interrupts are likely not enabled.

This resulted in debugfs_test.read_all_entries failing on haswell,
because of a timeout when reading the crc debugfs entry.

Solve this by enabling FIFO underrun reporting after the initial
fastset, which lets interrupts be generated as expected.

Testcase: debugfs_test.read_all_entries
Signed-off-by: Maarten Lankhorst <maarten.lankhorst at ubuntu.com>
---
 drivers/gpu/drm/i915/intel_display.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 737de251d0f8..8d42e6a910d4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12875,6 +12875,7 @@ static void intel_begin_crtc_commit(struct drm_crtc *crtc,
 static void intel_finish_crtc_commit(struct drm_crtc *crtc,
 				     struct drm_crtc_state *old_crtc_state)
 {
+	struct drm_i915_private *dev_priv = to_i915(crtc->dev);
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 	struct intel_atomic_state *old_intel_state =
 		to_intel_atomic_state(old_crtc_state->state);
@@ -12882,6 +12883,15 @@ static void intel_finish_crtc_commit(struct drm_crtc *crtc,
 		intel_atomic_get_new_crtc_state(old_intel_state, intel_crtc);
 
 	intel_pipe_update_end(new_crtc_state);
+
+	if (HAS_PCH_SPLIT(dev_priv) && new_crtc_state->update_pipe &&
+	    !needs_modeset(&new_crtc_state->base) &&
+	    old_crtc_state->mode.private_flags & I915_MODE_FLAG_INHERITED) {
+		intel_set_cpu_fifo_underrun_reporting(dev_priv, intel_crtc->pipe, true);
+
+		if (new_crtc_state->has_pch_encoder && !HAS_DDI(dev_priv))
+			intel_set_pch_fifo_underrun_reporting(dev_priv, intel_crtc->pipe, true);
+	}
 }
 
 /**
-- 
2.15.0