Patch "drm/i915: Perform an invalidate prior to executing golden renderstate" has been added to the 4.12-stable tree

This is a note to let you know that I've just added the patch titled

drm/i915: Perform an invalidate prior to executing golden renderstate

to the 4.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-i915-perform-an-invalidate-prior-to-executing-golden-renderstate.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Chris Wilson <[email protected]>
Date: Tue, 8 Aug 2017 14:19:04 +0100
Subject: drm/i915: Perform an invalidate prior to executing golden renderstate

From: Chris Wilson <[email protected]>

commit a0125a932e917cb507b682cb66645efdca1f8cab upstream.

As we may have just bound the renderstate into the GGTT for execution, we need to ensure that the GTT TLB are also flushed.

On snb-gt2, this would cause a random GPU hang at the start of a new context (e.g. boot) and on snb-gt1, it was causing the renderstate batch to take ~10s. It was the GPU hang that revealed the truth, as the CS gleefully executed beyond the end of the golden renderstate batch, a good indicator for a GTT TLB miss.

---
 drivers/gpu/drm/i915/i915_gem_render_state.c |    4 ++++
 1 file changed, 4 insertions(+)

@@ -242,6 +242,10 @@ int i915_gem_render_state_emit(struct dr
 			goto err_unpin;
 	}
 
+	ret = req->engine->emit_flush(req, EMIT_INVALIDATE);
+	if (ret)
+		goto err_unpin;
+
 	ret = req->engine->emit_bb_start(req,
 					 so->batch_offset, so->batch_size,
 					 I915_DISPATCH_SECURE);

Patches currently in stable-queue which might be from [email protected] are

queue-4.12/drm-i915-perform-an-invalidate-prior-to-executing-golden-renderstate.patch