Patch "drm/i915: Flush pipecontrol post-sync writes" has been added to the 4.2-stable tree

Patch "drm/i915: Flush pipecontrol post-sync writes" has been added to the 4.2-stable tree

[gregkh]

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

    drm/i915: Flush pipecontrol post-sync writes

to the 4.2-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-flush-pipecontrol-post-sync-writes.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 40a24488f5250d63341e74b9994159afc4589606 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 21 Aug 2015 16:08:41 +0100
Subject: drm/i915: Flush pipecontrol post-sync writes
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Chris Wilson <chris@chris-wilson.co.uk>

commit 40a24488f5250d63341e74b9994159afc4589606 upstream.

In order to flush the results from in-batch pipecontrol writes (used for
example in glQuery) before declaring the batch complete (and so declaring
the query results coherent), we need to set the FlushEnable bit in our
flushing pipecontrol. The FlushEnable bit "waits until all previous
writes of immediate data from post-sync circles are complete before
executing the next command".

I get GPU hangs on byt without flushing these writes (running ue4).
piglit has examples where the flush is required for correct rendering.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/i915/intel_lrc.c        |    1 +
 drivers/gpu/drm/i915/intel_ringbuffer.c |    2 ++
 2 files changed, 3 insertions(+)

--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -1250,6 +1250,7 @@ static int gen8_emit_flush_render(struct
 	if (flush_domains) {
 		flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
 		flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
+		flags |= PIPE_CONTROL_FLUSH_ENABLE;
 	}
 
 	if (invalidate_domains) {
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -342,6 +342,7 @@ gen7_render_ring_flush(struct intel_engi
 	if (flush_domains) {
 		flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
 		flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
+		flags |= PIPE_CONTROL_FLUSH_ENABLE;
 	}
 	if (invalidate_domains) {
 		flags |= PIPE_CONTROL_TLB_INVALIDATE;
@@ -412,6 +413,7 @@ gen8_render_ring_flush(struct intel_engi
 	if (flush_domains) {
 		flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
 		flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
+		flags |= PIPE_CONTROL_FLUSH_ENABLE;
 	}
 	if (invalidate_domains) {
 		flags |= PIPE_CONTROL_TLB_INVALIDATE;


Patches currently in stable-queue which might be from chris@chris-wilson.co.uk are

queue-4.2/drm-i915-flush-pipecontrol-post-sync-writes.patch
queue-4.2/drm-i915-deny-wrapping-an-userptr-into-a-framebuffer.patch