[PATCH 05/10] drm/i915: Move initial plane vblank wait into display code

Ville Syrjala
2026-04-10T15:05:13Z

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

The initial plane vblank wait operates on display registers,
so it really belongs in the display code proper. Move it there.

We can use intel_parent_irq_enabled() to determine if we can
rely on interrupts or not.

On average we should end up waiting half a frame here, so the
polling interval can be fairly long. 1 ms (which actually
makes poll_timeout_us() use ~250-1000 usec) seems good enough
to me.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
.../drm/i915/display/intel_initial_plane.c | 22 ++++++++++++++++++-
drivers/gpu/drm/i915/i915_initial_plane.c | 6 -----
drivers/gpu/drm/xe/display/xe_initial_plane.c | 19 ----------------
include/drm/intel/display_parent_interface.h | 2 --
4 files changed, 21 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_initial_plane.c b/drivers/gpu/drm/i915/display/intel_initial_plane.c
index 911d67dceba9..74e10d34c63c 100644
--- a/drivers/gpu/drm/i915/display/intel_initial_plane.c
+++ b/drivers/gpu/drm/i915/display/intel_initial_plane.c
@@ -1,14 +1,20 @@
// SPDX-License-Identifier: MIT
/* Copyright © 2025 Intel Corporation */

+#include <linux/iopoll.h>
+
#include <drm/drm_print.h>
#include <drm/intel/display_parent_interface.h>

+#include "intel_crtc.h"
+#include "intel_de.h"
#include "intel_display_core.h"
+#include "intel_display_regs.h"
#include "intel_display_types.h"
#include "intel_fb.h"
#include "intel_frontbuffer.h"
#include "intel_initial_plane.h"
+#include "intel_parent.h"
#include "intel_plane.h"

struct intel_initial_plane_configs {
@@ -18,8 +24,22 @@ struct intel_initial_plane_configs {
void intel_initial_plane_vblank_wait(struct intel_crtc *crtc)
{
struct intel_display *display = to_intel_display(crtc);
+ u32 start_ts, end_ts;
+ int ret;

- display->parent->initial_plane->vblank_wait(&crtc->base);
+ /* xe doesn't have interrupts enabled this early */
+ if (intel_parent_irq_enabled(display)) {
+ intel_crtc_wait_for_next_vblank(crtc);
+ return;
+ }
+
+ start_ts = intel_de_read(display, PIPE_FRMTMSTMP(crtc->pipe));
+
+ ret = poll_timeout_us(end_ts = intel_de_read(display, PIPE_FRMTMSTMP(crtc->pipe)),
+ end_ts != start_ts, 1000, 40 * 1000, false);
+ if (ret)
+ drm_warn(display->drm, "[CRTC:%d:%s] early vblank wait timed out\n",
+ crtc->base.base.id, crtc->base.name);
}

static const struct intel_plane_state *
diff --git a/drivers/gpu/drm/i915/i915_initial_plane.c b/drivers/gpu/drm/i915/i915_initial_plane.c
index 5cb1adde67b6..7775e657271b 100644
--- a/drivers/gpu/drm/i915/i915_initial_plane.c
+++ b/drivers/gpu/drm/i915/i915_initial_plane.c
@@ -16,11 +16,6 @@
#include "i915_drv.h"
#include "i915_initial_plane.h"

-static void i915_initial_plane_vblank_wait(struct drm_crtc *crtc)
-{
- intel_crtc_wait_for_next_vblank(to_intel_crtc(crtc));
-}
-
static enum intel_memory_type
initial_plane_memory_type(struct drm_i915_private *i915)
{
@@ -282,7 +277,6 @@ static void i915_plane_config_fini(struct intel_initial_plane_config *plane_conf
}

const struct intel_display_initial_plane_interface i915_display_initial_plane_interface = {
- .vblank_wait = i915_initial_plane_vblank_wait,
.alloc_obj = i915_alloc_initial_plane_obj,
.setup = i915_initial_plane_setup,
.config_fini = i915_plane_config_fini,
diff --git a/drivers/gpu/drm/xe/display/xe_initial_plane.c b/drivers/gpu/drm/xe/display/xe_initial_plane.c
index 8f2d0244c03f..37bd15d12169 100644
--- a/drivers/gpu/drm/xe/display/xe_initial_plane.c
+++ b/drivers/gpu/drm/xe/display/xe_initial_plane.c
@@ -7,8 +7,6 @@

#include "regs/xe_gtt_defs.h"

-#include "intel_crtc.h"
-#include "intel_display_regs.h"
#include "intel_display_types.h"
#include "intel_fb.h"
#include "intel_fb_pin.h"
@@ -19,22 +17,6 @@
#include "xe_mmio.h"
#include "xe_vram_types.h"

-/* Early xe has no irq */
-static void xe_initial_plane_vblank_wait(struct drm_crtc *_crtc)
-{
- struct intel_crtc *crtc = to_intel_crtc(_crtc);
- struct xe_device *xe = to_xe_device(crtc->base.dev);
- struct xe_reg pipe_frmtmstmp = XE_REG(i915_mmio_reg_offset(PIPE_FRMTMSTMP(crtc->pipe)));
- u32 timestamp;
- int ret;
-
- timestamp = xe_mmio_read32(xe_root_tile_mmio(xe), pipe_frmtmstmp);
-
- ret = xe_mmio_wait32_not(xe_root_tile_mmio(xe), pipe_frmtmstmp, ~0U, timestamp, 40000U, &timestamp, false);
- if (ret < 0)
- drm_warn(&xe->drm, "waiting for early vblank failed with %i\n", ret);
-}
-
static struct xe_bo *
initial_plane_bo(struct xe_device *xe,
struct intel_initial_plane_config *plane_config)
@@ -172,7 +154,6 @@ static void xe_plane_config_fini(struct intel_initial_plane_config *plane_config
}

const struct intel_display_initial_plane_interface xe_display_initial_plane_interface = {
- .vblank_wait = xe_initial_plane_vblank_wait,
.alloc_obj = xe_alloc_initial_plane_obj,
.setup = xe_initial_plane_setup,
.config_fini = xe_plane_config_fini,
diff --git a/include/drm/intel/display_parent_interface.h b/include/drm/intel/display_parent_interface.h
index 9041897c772e..b513e3f9924d 100644
--- a/include/drm/intel/display_parent_interface.h
+++ b/include/drm/intel/display_parent_interface.h
@@ -8,7 +8,6 @@

enum vlv_iosf_sb_unit;
struct dma_fence;
-struct drm_crtc;
struct drm_device;
struct drm_file;
struct drm_framebuffer;
@@ -87,7 +86,6 @@ struct intel_display_hdcp_interface {
};

struct intel_display_initial_plane_interface {
- void (*vblank_wait)(struct drm_crtc *crtc);
struct drm_gem_object *(*alloc_obj)(struct drm_device *drm, struct intel_initial_plane_config *plane_config);
int (*setup)(struct drm_plane_state *plane_state, struct intel_initial_plane_config *plane_config,
struct drm_framebuffer *fb, struct i915_vma *vma);
--
2.52.0