[Intel-gfx] [PATCH] drm/i915: Fix initial pipe underrun state tracking

[Daniel Vetter]

Since

commit 5c673b60a9b3b23486f4eda75c72e91d31d26a2b
Author: Daniel Vetter <daniel.vetter at ffwll.ch>
Date:   Fri Mar 7 20:34:46 2014 +0100

    drm/i915: Don't enable display error interrupts from the start

we don't enable underrun interrupts any more at takeover time.
Unfortunately I've forgotten to also adjust the sw-side tracking.

Since the code assumes that disabled pipes have underrun reporting
enabled set the disable flag on all pipes which are active at takeover
time. Without this underrun reporting wasn't enabled correctly on the
first modeset. Note that for fastboot this is another piece of state
that needs to be fixed up by enabling the underrung reporting after
watermarks have beend fixed up.

On ivb/hsw an additional effect of this regression was that also all
cpu crc reporting stopped working since the master error interrupt it
shared across all pipes and sources.

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Jani Nikula <jani.nikula at intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76150
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
 drivers/gpu/drm/i915/intel_display.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 7e4ea8d4e388..9b24ae4fb7bd 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -11502,6 +11502,14 @@ static void intel_sanitize_crtc(struct intel_crtc *crtc)
 			encoder->base.crtc = NULL;
 		}
 	}
+	if (crtc->active) {
+		/*
+		 * We start out with underrun reporting disabled to avoid races.
+		 * For correct bookkeeping mark this on active crtcs.
+		 */
+		crtc->cpu_fifo_underrun_disabled = true;
+		crtc->pch_fifo_underrun_disabled = true;
+	}
 }
 
 static void intel_sanitize_encoder(struct intel_encoder *encoder)
-- 
1.8.4.rc3