[Intel-gfx] [PATCH v2] drm/i915: Restore interrupt enabling after a reset

[Chris Wilson]

At least on i965g and i965gm, performing a device reset clobbers the IER
resulting in loss of interrupts thereafter. So, run the irq_postinstall
hook to restore them.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
Put it back to restoring the GMCH first. Hmm, maybe that's the key as to
which platforms require this?
---
 drivers/gpu/drm/i915/i915_reset.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c
index 5a067a4b3d5d..a1b74f605f2d 100644
--- a/drivers/gpu/drm/i915/i915_reset.c
+++ b/drivers/gpu/drm/i915/i915_reset.c
@@ -675,6 +675,7 @@ static int gt_reset(struct drm_i915_private *i915, unsigned int stalled_mask)
 {
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
+	unsigned long flags;
 	int err;
 
 	/*
@@ -685,12 +686,17 @@ static int gt_reset(struct drm_i915_private *i915, unsigned int stalled_mask)
 	if (err)
 		return err;
 
+	/* Restore IER as it may get clobbered on some platforms! (i965g[m]) */
+	spin_lock_irqsave(&i915->irq_lock, flags);
+	i915->drm.driver->irq_postinstall(&i915->drm);
+	spin_unlock_irqrestore(&i915->irq_lock, flags);
+
 	for_each_engine(engine, i915, id)
 		intel_engine_reset(engine, stalled_mask & ENGINE_MASK(id));
 
 	i915_gem_restore_fences(i915);
 
-	return err;
+	return 0;
 }
 
 static void reset_finish_engine(struct intel_engine_cs *engine)
-- 
2.20.1