On platforms capable of allowing 8K (7680 x 4320) modes, pinning 2 or
more framebuffers/scanout buffers results in only one that is mappable/
fenceable. Therefore, pageflipping between these 2 FBs where only one
is mappable/fenceable creates latencies large enough to miss alternate
vblanks thereby producing less optimal framerate.
This mainly happens because when i915_gem_object_pin_to_display_plane()
is called to pin one of the FB objs, the associated vma is identified
as misplaced and therefore i915_vma_unbind() is called which unbinds and
evicts it. This misplaced vma gets subseqently pinned only when
i915_gem_object_ggtt_pin_ww() is called without the mappable flag. This
results in a latency of ~10ms and happens every other vblank/repaint cycle.
Testcase:
Running Weston and weston-simple-egl on an Alderlake_S (ADLS) platform
with a 8K@60 mode results in only ~40 FPS. Since upstream Weston submits
a frame ~7ms before the next vblank, the latencies seen between atomic
commit and flip event is 7, 24 (7 + 16.66), 7, 24..... suggesting that
it misses the vblank every other frame.
Here is the ftrace snippet that shows the source of the ~10ms latency:
i915_gem_object_pin_to_display_plane() {
0.102 us | i915_gem_object_set_cache_level();
i915_gem_object_ggtt_pin_ww() {
0.390 us | i915_vma_instance();
0.178 us | i915_vma_misplaced();
i915_vma_unbind() {
__i915_active_wait() {
0.082 us | i915_active_acquire_if_busy();
0.475 us | }
intel_runtime_pm_get() {
0.087 us | intel_runtime_pm_acquire();
0.259 us | }
__i915_active_wait() {
0.085 us | i915_active_acquire_if_busy();
0.240 us | }
__i915_vma_evict() {
ggtt_unbind_vma() {
gen8_ggtt_clear_range() {
10507.255 us | }
10507.689 us | }
10508.516 us | }
Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_fb_pin.c | 11 +++++++++--
drivers/gpu/drm/i915/display/intel_overlay.c | 11 ++++++++---
drivers/gpu/drm/i915/gem/i915_gem_domain.c | 6 ++++--
drivers/gpu/drm/i915/gem/i915_gem_object.h | 3 ++-
4 files changed, 23 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_fb_pin.c b/drivers/gpu/drm/i915/display/intel_fb_pin.c
index 3f77f3013584..53c156d9a9f9 100644
--- a/drivers/gpu/drm/i915/display/intel_fb_pin.c
+++ b/drivers/gpu/drm/i915/display/intel_fb_pin.c
@@ -144,7 +144,7 @@ intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb,
if (!ret) {
vma = i915_gem_object_pin_to_display_plane(obj, &ww, alignment,
- view, pinctl);
+ view, pinctl, uses_fence);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto err_unpin;
@@ -218,9 +218,16 @@ int intel_plane_pin_fb(struct intel_plane_state *plane_state)
INTEL_INFO(dev_priv)->display.cursor_needs_physical;
if (!intel_fb_uses_dpt(fb)) {
+ struct intel_crtc *crtc = to_intel_crtc(plane_state->hw.crtc);
+ struct intel_crtc_state *crtc_state =
+ to_intel_crtc_state(crtc->base.state);
+ bool uses_fence = intel_plane_uses_fence(plane_state);
+ bool is_bigjoiner = crtc_state->bigjoiner ||
+ crtc_state->bigjoiner_slave;
+
vma = intel_pin_and_fence_fb_obj(fb, phys_cursor,
&plane_state->view.gtt,
- intel_plane_uses_fence(plane_state),
+ uses_fence && !is_bigjoiner,
&plane_state->flags);
if (IS_ERR(vma))
return PTR_ERR(vma);
diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c b/drivers/gpu/drm/i915/display/intel_overlay.c
index 7e3f5c6ca484..e9563b40b911 100644
--- a/drivers/gpu/drm/i915/display/intel_overlay.c
+++ b/drivers/gpu/drm/i915/display/intel_overlay.c
@@ -755,10 +755,14 @@ static u32 overlay_cmd_reg(struct drm_intel_overlay_put_image *params)
return cmd;
}
-static struct i915_vma *intel_overlay_pin_fb(struct drm_i915_gem_object *new_bo)
+static struct i915_vma *intel_overlay_pin_fb(struct drm_i915_gem_object *new_bo,
+ struct intel_overlay *overlay)
{
struct i915_gem_ww_ctx ww;
struct i915_vma *vma;
+ const struct intel_plane_state *plane_state =
+ to_intel_plane_state(overlay->crtc->base.primary->state);
+ bool uses_fence = intel_plane_uses_fence(plane_state);
int ret;
i915_gem_ww_ctx_init(&ww, true);
@@ -766,7 +770,8 @@ static struct i915_vma *intel_overlay_pin_fb(struct drm_i915_gem_object *new_bo)
ret = i915_gem_object_lock(new_bo, &ww);
if (!ret) {
vma = i915_gem_object_pin_to_display_plane(new_bo, &ww, 0,
- NULL, PIN_MAPPABLE);
+ NULL, PIN_MAPPABLE,
+ uses_fence);
ret = PTR_ERR_OR_ZERO(vma);
}
if (ret == -EDEADLK) {
@@ -802,7 +807,7 @@ static int intel_overlay_do_put_image(struct intel_overlay *overlay,
atomic_inc(&dev_priv->gpu_error.pending_fb_pin);
- vma = intel_overlay_pin_fb(new_bo);
+ vma = intel_overlay_pin_fb(new_bo, overlay);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto out_pin_section;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_domain.c b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
index b684a62bf3b0..b9108f13cc49 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_domain.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_domain.c
@@ -375,7 +375,8 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
struct i915_gem_ww_ctx *ww,
u32 alignment,
const struct i915_ggtt_view *view,
- unsigned int flags)
+ unsigned int flags,
+ bool uses_fence)
{
struct drm_i915_private *i915 = to_i915(obj->base.dev);
struct i915_vma *vma;
@@ -411,7 +412,8 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
*/
vma = ERR_PTR(-ENOSPC);
if ((flags & PIN_MAPPABLE) == 0 &&
- (!view || view->type == I915_GGTT_VIEW_NORMAL))
+ (!view || view->type == I915_GGTT_VIEW_NORMAL) &&
+ uses_fence)
vma = i915_gem_object_ggtt_pin_ww(obj, ww, view, 0, alignment,
flags | PIN_MAPPABLE |
PIN_NONBLOCK);
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index a5479ac7a4ad..e83564fa57ca 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -534,7 +534,8 @@ i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
struct i915_gem_ww_ctx *ww,
u32 alignment,
const struct i915_ggtt_view *view,
- unsigned int flags);
+ unsigned int flags,
+ bool uses_fence);
void i915_gem_object_make_unshrinkable(struct drm_i915_gem_object *obj);
void i915_gem_object_make_shrinkable(struct drm_i915_gem_object *obj);
--
2.31.1
