[Intel-gfx] [PATCH] drm/i915: Force vblanks around evasion when i915.watermark_test is set.

[Maarten Lankhorst]

This will make it more likely that intermediary watermarks cause fifo
underruns, which is useful when writing watermark specific tests,
to make it more likely to trigger FIFO underruns in intermediary watermarks.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 drivers/gpu/drm/i915/i915_params.c   | 1 +
 drivers/gpu/drm/i915/i915_params.h   | 1 +
 drivers/gpu/drm/i915/intel_display.c | 6 ++++++
 3 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 5e18cf9f754d..297d1cd53b15 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -45,6 +45,7 @@ struct i915_params i915 __read_mostly = {
 	.fastboot = 0,
 	.prefault_disable = 0,
 	.load_detect_test = 0,
+	.watermark_test = 0,
 	.reset = true,
 	.invert_brightness = 0,
 	.disable_display = 0,
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 1323261a0cdd..91f976c6bac6 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -57,6 +57,7 @@ struct i915_params {
 	bool fastboot;
 	bool prefault_disable;
 	bool load_detect_test;
+	bool watermark_test;
 	bool reset;
 	bool disable_display;
 	bool verbose_state_checks;
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 8bb8d36f5cb9..9dcf304c7b1f 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -14184,6 +14184,9 @@ static void intel_begin_crtc_commit(struct drm_crtc *crtc,
 		to_intel_crtc_state(old_crtc_state);
 	bool modeset = needs_modeset(crtc->state);
 
+	if (i915.watermark_test)
+		intel_wait_for_vblank(dev, intel_crtc->pipe);
+
 	/* Perform vblank evasion around commit operation */
 	intel_pipe_update_start(intel_crtc);
 
@@ -14207,6 +14210,9 @@ static void intel_finish_crtc_commit(struct drm_crtc *crtc,
 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 
 	intel_pipe_update_end(intel_crtc, NULL);
+
+	if (i915.watermark_test)
+		intel_wait_for_vblank(crtc->dev, intel_crtc->pipe);
 }
 
 /**
-- 
2.5.5