From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Thu, 24 May 2018 22:04:05 +0300
Subject: drm/i915: Try to suppress more spurious PCH underruns on ILK-IVB
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Git-commit: ea80a661fe56f27821a4fc40f8149be650ec913d
Patch-mainline: v4.19-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
My ILK seems to generate a spurious PCH underrun with most interlaced
HDMI modes. Add a second vblank wait to avoid it.
We have seen some spurious PCH underruns still in CI as well, some
of which seem to be progressive DP. The logs also point towards some
spurious underrins with progressive HDMI on SNB. While I don't have
a solid explanation for those let's try to kill all the birds with one
stone and always do the double wait.
Buzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106387
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180524190406.2973-1-ville.syrjala@linux.intel.com
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/i915/intel_display.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5523,9 +5523,16 @@ static void ironlake_crtc_enable(struct
if (HAS_PCH_CPT(dev_priv))
cpt_verify_modeset(dev, intel_crtc->pipe);
- /* Must wait for vblank to avoid spurious PCH FIFO underruns */
- if (intel_crtc->config->has_pch_encoder)
+ /*
+ * Must wait for vblank to avoid spurious PCH FIFO underruns.
+ * And a second vblank wait is needed at least on ILK with
+ * some interlaced HDMI modes. Let's do the double wait always
+ * in case there are more corner cases we don't know about.
+ */
+ if (intel_crtc->config->has_pch_encoder) {
intel_wait_for_vblank(dev_priv, pipe);
+ intel_wait_for_vblank(dev_priv, pipe);
+ }
intel_set_cpu_fifo_underrun_reporting(dev_priv, pipe, true);
intel_set_pch_fifo_underrun_reporting(dev_priv, pipe, true);
}