[PATCH] drm/i915: Enable FIFO underrun reporting after initial fastset, v4.

[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.

Changes since v1:
- Always enable CPU FIFO underrun reporting for >GEN2,
  and handle GEN2 correctly.
Changes since v2:
- Remove unneeded HAS_DDI, simplify GEN2 case.
Changes since v3:
- Use intel_crtc_pch_transcoder to determine pch transcoder for underruns. (Ville)
- Remove crtc->config dereference in intel_crtc_pch_transcoder. (Ville)

Testcase: debugfs_test.read_all_entries
Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171113144043.58658-1-maarten.lankhorst@linux.intel.com
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 23aa7191024e..a99728463d87 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1872,8 +1872,6 @@ enum pipe intel_crtc_pch_transcoder(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 
-	WARN_ON(!crtc->config->has_pch_encoder);
-
 	if (HAS_PCH_LPT(dev_priv))
 		return PIPE_A;
 	else
@@ -12940,6 +12938,7 @@ 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);
@@ -12947,6 +12946,20 @@ 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 (new_crtc_state->update_pipe &&
+	    !needs_modeset(&new_crtc_state->base) &&
+	    old_crtc_state->mode.private_flags & I915_MODE_FLAG_INHERITED) {
+		if (!IS_GEN2(dev_priv))
+			intel_set_cpu_fifo_underrun_reporting(dev_priv, intel_crtc->pipe, true);
+
+		if (new_crtc_state->has_pch_encoder) {
+			enum pipe pch_transcoder =
+				intel_crtc_pch_transcoder(intel_crtc);
+
+			intel_set_pch_fifo_underrun_reporting(dev_priv, pch_transcoder, true);
+		}
+	}
 }
 
 /**
-- 
2.15.0