[Intel-gfx] [PATCH 2/4] Revert "drm/i915/gem: Almagamate clflushes on suspend"

[Michael Cheng]

As we are making i915 more architecture-neutral, lets revert this commit
to the previous logic [1] to avoid using wbinvd_on_all_cpus.

[1]. ac05a22cd07a ("drm/i915/gem: Almagamate clflushes on suspend")

Suggested-by: Lucas De Marchi <lucas.demar...@intel.com>
Signed-off-by: Michael Cheng <michael.ch...@intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_pm.c | 41 +++++++++++++++++---------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pm.c 
b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
index 00359ec9d58b..3f20961bb59b 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_pm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
@@ -13,13 +13,6 @@
 #include "i915_driver.h"
 #include "i915_drv.h"
 
-#if defined(CONFIG_X86)
-#include <asm/smp.h>
-#else
-#define wbinvd_on_all_cpus() \
-       pr_warn(DRIVER_NAME ": Missing cache flush in %s\n", __func__)
-#endif
-
 void i915_gem_suspend(struct drm_i915_private *i915)
 {
        GEM_TRACE("%s\n", dev_name(i915->drm.dev));
@@ -123,6 +116,13 @@ int i915_gem_backup_suspend(struct drm_i915_private *i915)
        return ret;
 }
 
+static struct drm_i915_gem_object *first_mm_object(struct list_head *list)
+{
+       return list_first_entry_or_null(list,
+                                       struct drm_i915_gem_object,
+                                       mm.link);
+}
+
 void i915_gem_suspend_late(struct drm_i915_private *i915)
 {
        struct drm_i915_gem_object *obj;
@@ -132,7 +132,6 @@ void i915_gem_suspend_late(struct drm_i915_private *i915)
                NULL
        }, **phase;
        unsigned long flags;
-       bool flush = false;
 
        /*
         * Neither the BIOS, ourselves or any other kernel
@@ -158,15 +157,29 @@ void i915_gem_suspend_late(struct drm_i915_private *i915)
 
        spin_lock_irqsave(&i915->mm.obj_lock, flags);
        for (phase = phases; *phase; phase++) {
-               list_for_each_entry(obj, *phase, mm.link) {
-                       if (!(obj->cache_coherent & 
I915_BO_CACHE_COHERENT_FOR_READ))
-                               flush |= (obj->read_domains & 
I915_GEM_DOMAIN_CPU) == 0;
-                       __start_cpu_write(obj); /* presume auto-hibernate */
+               LIST_HEAD(keep);
+
+               while ((obj = first_mm_object(*phase))) {
+                       list_move_tail(&obj->mm.link, &keep);
+
+                       /* Beware the background _i915_gem_free_objects */
+                       if (!kref_get_unless_zero(&obj->base.refcount))
+                               continue;
+
+                       spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
+
+                       i915_gem_object_lock(obj, NULL);
+                       drm_WARN_ON(&i915->drm,
+                           i915_gem_object_set_to_gtt_domain(obj, false));
+                       i915_gem_object_unlock(obj);
+                       i915_gem_object_put(obj);
+
+                       spin_lock_irqsave(&i915->mm.obj_lock, flags);
                }
+
+               list_splice_tail(&keep, *phase);
        }
        spin_unlock_irqrestore(&i915->mm.obj_lock, flags);
-       if (flush)
-               wbinvd_on_all_cpus();
 }
 
 int i915_gem_freeze(struct drm_i915_private *i915)
-- 
2.25.1