[Intel-gfx] [PATCH v2] drm/i915: Also perform gpu reset under execlist mode.

[bing.niu at intel.com]

From: "Niu,Bing" <bing.niu at intel.com>

It is found that i915 will not reset gpu under execlist mode when
unload module. that will lead to some issues when unload/load module
with different submission mode. e.g. from execlist mode to ring
buffer mode via loading/unloading i915. Because HW is not in a reset
state and registers are not clean under such condition.

Signed-off-by: Niu,Bing <bing.niu at intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index be35f04..7855dd3 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -5115,6 +5115,14 @@ i915_gem_cleanup_ringbuffer(struct drm_device *dev)
 
 	for_each_ring(ring, dev_priv, i)
 		dev_priv->gt.cleanup_ring(ring);
+
+    if (i915.enable_execlists)
+            /*
+             * Neither the BIOS, ourselves or any other kernel
+             * expects the system to be in execlists mode on startup,
+             * so we need to reset the GPU back to legacy mode.
+             */
+            intel_gpu_reset(dev);
 }
 
 static void
-- 
1.7.9.5