From 9a4a58bf5afa9558161cbd329f4f071e739ce7c1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Wed, 29 Apr 2020 13:10:34 +0300
Subject: drm/i915: Suppress spurious underruns on gen2
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Git-commit: f6a7d3952cbed2c1e07d945dbb36f5c34200e9c1
Patch-mainline: v5.9-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
Often we seem to detect an underrun right after modeset on gen2.
It seems to be a spurious detection (potentially the pipe is still
in a wonky state when we enable the planes). An extra vblank wait
seems to cure it.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200429101034.8208-13-ville.syrjala@linux.intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/display/intel_display.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 4fdc9ccfea2a..182cef0dc2fd 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -7526,6 +7526,10 @@ static void i9xx_crtc_enable(struct intel_atomic_state *state,
intel_crtc_vblank_on(new_crtc_state);
intel_encoders_enable(state, crtc);
+
+ /* prevents spurious underruns */
+ if (IS_GEN(dev_priv, 2))
+ intel_wait_for_vblank(dev_priv, pipe);
}
static void i9xx_pfit_disable(const struct intel_crtc_state *old_crtc_state)
--
2.29.2