FAILED: patch "[PATCH] drm/i915: Use correct index for backtracking HUNG semaphores" failed to apply to 4.8-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.8-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 27399eeec28ff33a0c5216a80cf57cbc6ba3c15e Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 3 Oct 2016 13:45:16 +0100
Subject: [PATCH] drm/i915: Use correct index for backtracking HUNG semaphores

When decoding the semaphores inside hangcheck, we need to use the hw-id
and not the local array index.

Fixes: de1add360522 ("drm/i915: Decouple execbuf uAPI ...")
Testcase: igt/gem_exec_whisper/hang # gen6-7
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161003124516.12388-3-chris@chris-wilson.co.uk
(cherry picked from commit 348b9b1192144e13b779f8f9be301d492bebaff2)
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 13fae1c9dcc8..3fc286cd1157 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -2822,7 +2822,7 @@ semaphore_wait_to_signaller_ring(struct intel_engine_cs *engine, u32 ipehr,
 			if (engine == signaller)
 				continue;
 
-			if (offset == signaller->semaphore.signal_ggtt[engine->id])
+			if (offset == signaller->semaphore.signal_ggtt[engine->hw_id])
 				return signaller;
 		}
 	} else {
@@ -2832,13 +2832,13 @@ semaphore_wait_to_signaller_ring(struct intel_engine_cs *engine, u32 ipehr,
 			if(engine == signaller)
 				continue;
 
-			if (sync_bits == signaller->semaphore.mbox.wait[engine->id])
+			if (sync_bits == signaller->semaphore.mbox.wait[engine->hw_id])
 				return signaller;
 		}
 	}
 
-	DRM_DEBUG_DRIVER("No signaller ring found for ring %i, ipehr 0x%08x, offset 0x%016llx\n",
-			 engine->id, ipehr, offset);
+	DRM_DEBUG_DRIVER("No signaller ring found for %s, ipehr 0x%08x, offset 0x%016llx\n",
+			 engine->name, ipehr, offset);
 
 	return ERR_PTR(-ENODEV);
 }