i915 has this really nice, infrastructure where everything becomes
complicated, GGTT needs eviction, etc..

Lets not do that, and make the dumbest possible interface instead.
Try to retrieve the VMA from old_plane_state, or intel_fbdev if kernel
fb.

Signed-off-by: Maarten Lankhorst <maarten.lankho...@linux.intel.com>
---
 .../gpu/drm/i915/display/intel_atomic_plane.c |  2 +-
 drivers/gpu/drm/i915/display/intel_cursor.c   |  2 +-
 drivers/gpu/drm/i915/display/intel_fb_pin.c   |  3 +-
 drivers/gpu/drm/i915/display/intel_fb_pin.h   |  3 +-
 drivers/gpu/drm/i915/display/intel_fbdev.c    |  5 ++
 drivers/gpu/drm/i915/display/intel_fbdev.h    |  8 ++++
 .../gpu/drm/xe/compat-i915-headers/i915_vma.h |  3 ++
 drivers/gpu/drm/xe/display/xe_fb_pin.c        | 46 +++++++++++++++++--
 8 files changed, 64 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c 
b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
index b083b985d170..ee82f4b6abbc 100644
--- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
+++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
@@ -1123,7 +1123,7 @@ intel_prepare_plane_fb(struct drm_plane *_plane,
        if (!obj)
                return 0;
 
-       ret = intel_plane_pin_fb(new_plane_state);
+       ret = intel_plane_pin_fb(new_plane_state, old_plane_state);
        if (ret)
                return ret;
 
diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c 
b/drivers/gpu/drm/i915/display/intel_cursor.c
index 2118b87ccb10..dab938566c94 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -761,7 +761,7 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
        if (ret)
                goto out_free;
 
-       ret = intel_plane_pin_fb(new_plane_state);
+       ret = intel_plane_pin_fb(new_plane_state, old_plane_state);
        if (ret)
                goto out_free;
 
diff --git a/drivers/gpu/drm/i915/display/intel_fb_pin.c 
b/drivers/gpu/drm/i915/display/intel_fb_pin.c
index be095cc696ba..24bcaea53f0b 100644
--- a/drivers/gpu/drm/i915/display/intel_fb_pin.c
+++ b/drivers/gpu/drm/i915/display/intel_fb_pin.c
@@ -234,7 +234,8 @@ void intel_unpin_fb_vma(struct i915_vma *vma, unsigned long 
flags)
        i915_vma_put(vma);
 }
 
-int intel_plane_pin_fb(struct intel_plane_state *plane_state)
+int intel_plane_pin_fb(struct intel_plane_state *plane_state,
+                      const struct intel_plane_state *old_plane_state)
 {
        struct intel_plane *plane = to_intel_plane(plane_state->uapi.plane);
        struct drm_i915_private *dev_priv = to_i915(plane->base.dev);
diff --git a/drivers/gpu/drm/i915/display/intel_fb_pin.h 
b/drivers/gpu/drm/i915/display/intel_fb_pin.h
index de0efaa25905..48675e6233f0 100644
--- a/drivers/gpu/drm/i915/display/intel_fb_pin.h
+++ b/drivers/gpu/drm/i915/display/intel_fb_pin.h
@@ -22,7 +22,8 @@ intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb,
 
 void intel_unpin_fb_vma(struct i915_vma *vma, unsigned long flags);
 
-int intel_plane_pin_fb(struct intel_plane_state *plane_state);
+int intel_plane_pin_fb(struct intel_plane_state *new_plane_state,
+                      const struct intel_plane_state *old_plane_state);
 void intel_plane_unpin_fb(struct intel_plane_state *old_plane_state);
 
 #endif
diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c 
b/drivers/gpu/drm/i915/display/intel_fbdev.c
index bda702c2cab8..2d5bf26b2aad 100644
--- a/drivers/gpu/drm/i915/display/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/display/intel_fbdev.c
@@ -695,3 +695,8 @@ struct intel_framebuffer *intel_fbdev_framebuffer(struct 
intel_fbdev *fbdev)
 
        return to_intel_framebuffer(fbdev->helper.fb);
 }
+
+struct i915_vma *intel_fbdev_vma_pointer(struct intel_fbdev *fbdev)
+{
+       return fbdev ? fbdev->vma : NULL;
+}
diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.h 
b/drivers/gpu/drm/i915/display/intel_fbdev.h
index 08de2d5b3433..24a3434558cb 100644
--- a/drivers/gpu/drm/i915/display/intel_fbdev.h
+++ b/drivers/gpu/drm/i915/display/intel_fbdev.h
@@ -17,6 +17,8 @@ struct intel_framebuffer;
 void intel_fbdev_setup(struct drm_i915_private *dev_priv);
 void intel_fbdev_set_suspend(struct drm_device *dev, int state, bool 
synchronous);
 struct intel_framebuffer *intel_fbdev_framebuffer(struct intel_fbdev *fbdev);
+struct i915_vma *intel_fbdev_vma_pointer(struct intel_fbdev *fbdev);
+
 #else
 static inline void intel_fbdev_setup(struct drm_i915_private *dev_priv)
 {
@@ -30,6 +32,12 @@ static inline struct intel_framebuffer 
*intel_fbdev_framebuffer(struct intel_fbd
 {
        return NULL;
 }
+
+static inline struct i915_vma *intel_fbdev_vma_pointer(struct intel_fbdev 
*fbdev)
+{
+       return NULL;
+}
+
 #endif
 
 #endif /* __INTEL_FBDEV_H__ */
diff --git a/drivers/gpu/drm/xe/compat-i915-headers/i915_vma.h 
b/drivers/gpu/drm/xe/compat-i915-headers/i915_vma.h
index a20d2638ea7a..193382f97823 100644
--- a/drivers/gpu/drm/xe/compat-i915-headers/i915_vma.h
+++ b/drivers/gpu/drm/xe/compat-i915-headers/i915_vma.h
@@ -9,6 +9,8 @@
 #include <uapi/drm/i915_drm.h>
 #include <drm/drm_mm.h>
 
+#include <linux/refcount.h>
+
 /* We don't want these from i915_drm.h in case of Xe */
 #undef I915_TILING_X
 #undef I915_TILING_Y
@@ -18,6 +20,7 @@
 struct xe_bo;
 
 struct i915_vma {
+       refcount_t ref;
        struct xe_bo *bo, *dpt;
        struct drm_mm_node node;
 };
diff --git a/drivers/gpu/drm/xe/display/xe_fb_pin.c 
b/drivers/gpu/drm/xe/display/xe_fb_pin.c
index 6ebda3ded8b4..75e030f0fb70 100644
--- a/drivers/gpu/drm/xe/display/xe_fb_pin.c
+++ b/drivers/gpu/drm/xe/display/xe_fb_pin.c
@@ -8,6 +8,7 @@
 #include "intel_dpt.h"
 #include "intel_fb.h"
 #include "intel_fb_pin.h"
+#include "intel_fbdev.h"
 #include "xe_ggtt.h"
 #include "xe_gt.h"
 #include "xe_pm.h"
@@ -348,6 +349,7 @@ static struct i915_vma *__xe_pin_fb_vma(struct 
intel_framebuffer *fb,
        if (!vma)
                return ERR_PTR(-ENOMEM);
 
+       refcount_set(&vma->ref, 1);
        if (IS_DGFX(to_xe_device(bo->ttm.base.dev)) &&
            intel_fb_rc_ccs_cc_plane(&fb->base) >= 0 &&
            !(bo->flags & XE_BO_FLAG_NEEDS_CPU_ACCESS)) {
@@ -407,6 +409,9 @@ static void __xe_unpin_fb_vma(struct i915_vma *vma, struct 
intel_framebuffer *fb
        struct xe_device *xe = to_xe_device(vma->bo->ttm.base.dev);
        struct xe_ggtt *ggtt = xe_device_get_root_tile(xe)->mem.ggtt;
 
+       if (!refcount_dec_and_test(&vma->ref))
+               return;
+
        if (vma->dpt) {
                xe_ggtt_remove_bo(ggtt, vma->dpt);
                xe_fb_dpt_unpin_free(vma, fb);
@@ -439,20 +444,53 @@ void intel_unpin_fb_vma(struct i915_vma *vma, unsigned 
long flags)
        __xe_unpin_fb_vma(vma, NULL);
 }
 
-int intel_plane_pin_fb(struct intel_plane_state *plane_state)
+static bool reuse_vma(struct intel_plane_state *new_plane_state,
+                     const struct intel_plane_state *old_plane_state)
 {
-       struct drm_framebuffer *fb = plane_state->hw.fb;
+       struct intel_framebuffer *fb = 
to_intel_framebuffer(new_plane_state->hw.fb);
+       struct xe_device *xe = to_xe_device(fb->base.dev);
+       struct i915_vma *vma;
+
+       if (old_plane_state->hw.fb == new_plane_state->hw.fb &&
+           !memcmp(&old_plane_state->view.gtt,
+                   &new_plane_state->view.gtt,
+                   sizeof(new_plane_state->view.gtt))) {
+               vma = old_plane_state->ggtt_vma;
+               goto found;
+       }
+
+       if (fb == intel_fbdev_framebuffer(xe->display.fbdev.fbdev)) {
+               vma = intel_fbdev_vma_pointer(xe->display.fbdev.fbdev);
+               if (vma)
+                       goto found;
+       }
+
+       return false;
+
+found:
+       refcount_inc(&vma->ref);
+       new_plane_state->ggtt_vma = vma;
+       return true;
+}
+
+int intel_plane_pin_fb(struct intel_plane_state *new_plane_state,
+                      const struct intel_plane_state *old_plane_state)
+{
+       struct drm_framebuffer *fb = new_plane_state->hw.fb;
        struct xe_bo *bo = intel_fb_obj(fb);
        struct i915_vma *vma;
 
+       if (reuse_vma(new_plane_state, old_plane_state))
+               return 0;
+
        /* We reject creating !SCANOUT fb's, so this is weird.. */
        drm_WARN_ON(bo->ttm.base.dev, !(bo->flags & XE_BO_FLAG_SCANOUT));
 
-       vma = __xe_pin_fb_vma(to_intel_framebuffer(fb), &plane_state->view.gtt);
+       vma = __xe_pin_fb_vma(to_intel_framebuffer(fb), 
&new_plane_state->view.gtt);
        if (IS_ERR(vma))
                return PTR_ERR(vma);
 
-       plane_state->ggtt_vma = vma;
+       new_plane_state->ggtt_vma = vma;
        return 0;
 }
 
-- 
2.43.0

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