[FOR CI 4/5] drm/xe/display: Disable preemption in the most critical section

[Maarten Lankhorst <dev@lankhorst.se>]

Lets see what happens if we only disable preemption in the critical
section to ensure we do run as fast as possible without disabling
too much.

Second attempt: Disable preemption, but keep interrupts enabled.

Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/display/intel_crtc.c   | 14 ++++++++++++++
 drivers/gpu/drm/i915/display/intel_cursor.c | 18 +++++++++++++++++-
 drivers/gpu/drm/i915/display/intel_vblank.c |  9 ++++++++-
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index f34745b5ea497..939ef48859f16 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -569,6 +569,10 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 
 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 		local_irq_disable();
+#ifndef I915
+	else
+		preempt_disable();
+#endif
 
 	crtc->debug.min_vbl = evade.min;
 	crtc->debug.max_vbl = evade.max;
@@ -588,6 +592,11 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 irq_disable:
 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 		local_irq_disable();
+#ifndef I915
+	else
+		preempt_disable();
+#endif
+
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE)
@@ -686,6 +695,10 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
 	    intel_crtc_has_type(new_crtc_state, INTEL_OUTPUT_DSI))
 		icl_dsi_frame_update(new_crtc_state);
 
+#if !defined(I915) && IS_ENABLED(CONFIG_PREEMPT_RT)
+	preempt_enable();
+#endif
+
 	/* We're still in the vblank-evade critical section, this can't race.
 	 * Would be slightly nice to just grab the vblank count and arm the
 	 * event outside of the critical section - the spinlock might spin for a
@@ -733,6 +746,7 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
 	if (!state->base.legacy_cursor_update)
 		intel_vrr_send_push(NULL, new_crtc_state);
 
+	/* Re-enable irqs here for !RT */
 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 		local_irq_enable();
 
diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index 780fcae77a984..50ca39eb09145 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -912,6 +912,7 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 
 	intel_psr_lock(crtc_state);
 
+	bool vblanked = false;
 	if (!drm_WARN_ON(display->drm, drm_crtc_vblank_get(&crtc->base))) {
 		/*
 		 * TODO: maybe check if we're still in PSR
@@ -921,13 +922,21 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 
 		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 			local_irq_disable();
+#ifndef I915
+		else
+			preempt_disable();
+#endif
 
 		intel_vblank_evade(&evade);
 
-		drm_crtc_vblank_put(&crtc->base);
+		vblanked = true;
 	} else {
 		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 			local_irq_disable();
+#ifndef I915
+		else
+			preempt_disable();
+#endif
 	}
 
 	if (new_plane_state->uapi.visible) {
@@ -939,6 +948,10 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 
 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 		local_irq_enable();
+#ifndef I915
+	else
+		preempt_enable();
+#endif
 
 	intel_psr_unlock(crtc_state);
 
@@ -955,6 +968,9 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		intel_plane_unpin_fb(old_plane_state);
 	}
 
+	if (vblanked)
+		drm_crtc_vblank_put(&crtc->base);
+
 out_free:
 	if (new_crtc_state)
 		intel_crtc_destroy_state(&crtc->base, &new_crtc_state->uapi);
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index 7826f29619a14..1437a27ac5878 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -763,11 +763,18 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade)
 
 		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 			local_irq_enable();
+#ifndef I915
+		else
+			preempt_enable();
+#endif
 
 		timeout = schedule_timeout(timeout);
-
 		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 			local_irq_disable();
+#ifndef I915
+		else
+			preempt_disable();
+#endif
 	}
 
 	finish_wait(wq, &wait);
-- 
2.51.0