drm/i915: Fix system hang with EI UP masked on Haswell

Previously with commit 51cd3ac96d6d
("drm/i915: Don't mask EI UP interrupt on IVB|SNB") certain,
seemingly unrelated bit (GEN6_PM_RP_UP_EI_EXPIRED) was needed
to be unmasked for IVB and SNB in order to prevent system hang
with chained batchbuffers.

Our CI was seeing incomplete results with tests that used
chained batches and it was found out that HSW needs to have this
same bit unmasked to reliably survive chained batches.

Always unmask GEN6_PM_RP_UP_EI_EXPIRED on Haswell to
prevent system hang with batch chaining.

Testcase: igt/gem_exec_fence/nb-await-default
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=100672
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1492082127-29007-1-git-send-email-mika.kuoppala@intel.com
(cherry picked from commit 3396a273851c14634b98bb27be37508b06df94f4)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index d9d196977f4a047febadefc21335303300d97e7b..fd97fe00cd0d2ad00e1c7258eeb51ecf0f60d4c1 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -4252,12 +4252,12 @@ void intel_irq_init(struct drm_i915_private *dev_priv)
        dev_priv->rps.pm_intrmsk_mbz = 0;
 
        /*
-        * SNB,IVB can while VLV,CHV may hard hang on looping batchbuffer
+        * SNB,IVB,HSW can while VLV,CHV may hard hang on looping batchbuffer
         * if GEN6_PM_UP_EI_EXPIRED is masked.
         *
         * TODO: verify if this can be reproduced on VLV,CHV.
         */
-       if (INTEL_INFO(dev_priv)->gen <= 7 && !IS_HASWELL(dev_priv))
+       if (INTEL_INFO(dev_priv)->gen <= 7)
                dev_priv->rps.pm_intrmsk_mbz |= GEN6_PM_RP_UP_EI_EXPIRED;
 
        if (INTEL_INFO(dev_priv)->gen >= 8)