From 681c774d349018c0f47a770133b952f50328d957 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 9 Jul 2019 09:17:18 +0100
Subject: drm/i915/userptr: Don't mark readonly objects as dirty
Git-commit: 681c774d349018c0f47a770133b952f50328d957
Patch-mainline: v5.4-rc1
References: bsc#1152489

If we map an object as readonly into the GTT, we know that the GPU
cannot have written to it and so the object is not dirty and we don't
need to flush the writes back to the system.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190709081718.27843-1-chris@chris-wilson.co.uk
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/i915/gem/i915_gem_userptr.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
@@ -663,6 +663,14 @@ i915_gem_userptr_put_pages(struct drm_i9
 	__i915_gem_object_release_shmem(obj, pages, true);
 	i915_gem_gtt_finish_pages(obj, pages);
 
+	/*
+	 * We always mark objects as dirty when they are used by the GPU,
+	 * just in case. However, if we set the vma as being read-only we know
+	 * that the object will never have been written to.
+	 */
+	if (i915_gem_object_is_readonly(obj))
+		obj->mm.dirty = false;
+
 	for_each_sgt_page(page, sgt_iter, pages) {
 		if (obj->mm.dirty)
 			set_page_dirty(page);