[FOR CI 0/5] Testing PREEMPT_RT with disabling interrupts in the most critical section.

[FOR CI 0/5] Testing PREEMPT_RT with disabling interrupts in the most critical section.

[Maarten Lankhorst]

*** BLURB HERE ***

Maarten Lankhorst (3):
  drm/xe: Bump xe_device_l2_flush even higher
  drm/i915/display: Disable interrupts on xe for realtime preemption
  [FOR-CI] PREEMPT_RT injection

Mike Galbraith (2):
  drm/i915: Use preempt_disable/enable_rt() where recommended
  drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

 drivers/gpu/drm/i915/Kconfig.debug          | 15 -------
 drivers/gpu/drm/i915/display/intel_crtc.c   | 13 ++++--
 drivers/gpu/drm/i915/display/intel_cursor.c |  9 ++--
 drivers/gpu/drm/i915/display/intel_vblank.c | 49 ++++++++++++++++-----
 drivers/gpu/drm/i915/display/intel_vblank.h |  9 ++++
 drivers/gpu/drm/xe/Kconfig.debug            |  5 +++
 drivers/gpu/drm/xe/xe_device.c              |  4 +-
 kernel/Kconfig.preempt                      |  3 +-
 8 files changed, 69 insertions(+), 38 deletions(-)

-- 
2.51.0

[FOR CI 1/5] drm/xe: Bump xe_device_l2_flush even higher

[Maarten Lankhorst]

It turns out for some applications 1 ms is not enough, and 2 ms is
needed.

Failing to flush causes a catastrophic display update failure,
so we should prevent it if possible.

Add an even bigger margin of 5 ms, and complain loudly if we ever exceed
it.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6097
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/xe/xe_device.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index 5f6a412b571c7..f6704c57e87ca 100644
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -1077,8 +1077,8 @@ void xe_device_l2_flush(struct xe_device *xe)
 	spin_lock(&gt->global_invl_lock);
 
 	xe_mmio_write32(&gt->mmio, XE2_GLOBAL_INVAL, 0x1);
-	if (xe_mmio_wait32(&gt->mmio, XE2_GLOBAL_INVAL, 0x1, 0x0, 1000, NULL, true))
-		xe_gt_err_once(gt, "Global invalidation timeout\n");
+	if (xe_mmio_wait32(&gt->mmio, XE2_GLOBAL_INVAL, 0x1, 0x0, 5000, NULL, true))
+		xe_gt_err(gt, "Global invalidation timeout\n");
 
 	spin_unlock(&gt->global_invl_lock);
 
-- 
2.51.0

[FOR CI 2/5] drm/i915: Use preempt_disable/enable_rt() where recommended

[Maarten Lankhorst]

From: Mike Galbraith <umgwanakikbuti@gmail.com>

Mario Kleiner suggest in commit
  ad3543ede630f ("drm/intel: Push get_scanout_position() timestamping into kms driver.")

a spots where preemption should be disabled on PREEMPT_RT. The
difference is that on PREEMPT_RT the intel_uncore::lock disables neither
preemption nor interrupts and so region remains preemptible.

The area covers only register reads and writes. The part that worries me
is:
- __intel_get_crtc_scanline() the worst case is 100us if no match is
  found.

- intel_crtc_scanlines_since_frame_timestamp() not sure how long this
  may take in the worst case.

It was in the RT queue for a while and nobody complained.
Disable preemption on PREEPMPT_RT during timestamping.

[bigeasy: patch description.]

Cc: Mario Kleiner <mario.kleiner.de@gmail.com>
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/display/intel_vblank.c | 43 ++++++++++++++++-----
 1 file changed, 33 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index 2fc0c1c0bb876..5206a81f85554 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -315,6 +315,20 @@ static void intel_vblank_section_exit(struct intel_display *display)
 	struct drm_i915_private *i915 = to_i915(display->drm);
 	spin_unlock(&i915->uncore.lock);
 }
+
+static void intel_vblank_section_enter_irqf(struct intel_display *display, unsigned long *flags)
+	__acquires(i915->uncore.lock)
+{
+	struct drm_i915_private *i915 = to_i915(display->drm);
+	spin_lock_irqsave(&i915->uncore.lock, *flags);
+}
+
+static void intel_vblank_section_exit_irqf(struct intel_display *display, unsigned long flags)
+	__releases(i915->uncore.lock)
+{
+	struct drm_i915_private *i915 = to_i915(display->drm);
+	spin_unlock_irqrestore(&i915->uncore.lock, flags);
+}
 #else
 static void intel_vblank_section_enter(struct intel_display *display)
 {
@@ -323,6 +337,17 @@ static void intel_vblank_section_enter(struct intel_display *display)
 static void intel_vblank_section_exit(struct intel_display *display)
 {
 }
+
+static void intel_vblank_section_enter_irqf(struct intel_display *display, unsigned long *flags)
+{
+	*flags = 0;
+}
+
+static void intel_vblank_section_exit_irqf(struct intel_display *display, unsigned long flags)
+{
+	if (flags)
+		return;
+}
 #endif
 
 static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc,
@@ -359,10 +384,10 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc,
 	 * timing critical raw register reads, potentially with
 	 * preemption disabled, so the following code must not block.
 	 */
-	local_irq_save(irqflags);
-	intel_vblank_section_enter(display);
+	intel_vblank_section_enter_irqf(display, &irqflags);
 
-	/* preempt_disable_rt() should go right here in PREEMPT_RT patchset. */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_disable();
 
 	/* Get optional system timestamp before query. */
 	if (stime)
@@ -426,10 +451,10 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc,
 	if (etime)
 		*etime = ktime_get();
 
-	/* preempt_enable_rt() should go right here in PREEMPT_RT patchset. */
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		preempt_enable();
 
-	intel_vblank_section_exit(display);
-	local_irq_restore(irqflags);
+	intel_vblank_section_exit_irqf(display, irqflags);
 
 	/*
 	 * While in vblank, position will be negative
@@ -467,13 +492,11 @@ int intel_get_crtc_scanline(struct intel_crtc *crtc)
 	unsigned long irqflags;
 	int position;
 
-	local_irq_save(irqflags);
-	intel_vblank_section_enter(display);
+	intel_vblank_section_enter_irqf(display, &irqflags);
 
 	position = __intel_get_crtc_scanline(crtc);
 
-	intel_vblank_section_exit(display);
-	local_irq_restore(irqflags);
+	intel_vblank_section_exit_irqf(display, irqflags);
 
 	return position;
 }
-- 
2.51.0

[FOR CI 3/5] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

[Maarten Lankhorst]

From: Mike Galbraith <umgwanakikbuti@gmail.com>

Commit
   8d7849db3eab7 ("drm/i915: Make sprite updates atomic")

started disabling interrupts across atomic updates. This breaks on PREEMPT_RT
because within this section the code attempt to acquire spinlock_t locks which
are sleeping locks on PREEMPT_RT.

According to the comment the interrupts are disabled to avoid random delays and
not required for protection or synchronisation.
If this needs to happen with disabled interrupts on PREEMPT_RT, and the
whole section is restricted to register access then all sleeping locks
need to be acquired before interrupts are disabled and some function
maybe moved after enabling interrupts again.
This includes:
- prepare_to_wait() + finish_wait() due its wake queue.
- drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock.
- skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and
  maybe others due to intel_uncore::lock
- drm_crtc_arm_vblank_event() due to drm_device::event_lock and
  drm_device::vblank_time_lock.

Don't disable interrupts on PREEMPT_RT during atomic updates.

[bigeasy: drop local locks, commit message]

Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/display/intel_crtc.c   | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_cursor.c | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_vblank.c | 6 ++++--
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index d300ba1dcd2c4..f34745b5ea497 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -567,7 +567,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	 */
 	intel_psr_wait_for_idle_locked(new_crtc_state);
 
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 
 	crtc->debug.min_vbl = evade.min;
 	crtc->debug.max_vbl = evade.max;
@@ -585,7 +586,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	return;
 
 irq_disable:
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE)
@@ -731,7 +733,8 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
 	if (!state->base.legacy_cursor_update)
 		intel_vrr_send_push(NULL, new_crtc_state);
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	if (intel_vgpu_active(dev_priv))
 		goto out;
diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index c47c849358714..780fcae77a984 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -919,13 +919,15 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		 */
 		intel_psr_wait_for_idle_locked(crtc_state);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 
 		intel_vblank_evade(&evade);
 
 		drm_crtc_vblank_put(&crtc->base);
 	} else {
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	if (new_plane_state->uapi.visible) {
@@ -935,7 +937,8 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		intel_plane_disable_arm(NULL, plane, crtc_state);
 	}
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	intel_psr_unlock(crtc_state);
 
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index 5206a81f85554..7826f29619a14 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -761,11 +761,13 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade)
 			break;
 		}
 
-		local_irq_enable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_enable();
 
 		timeout = schedule_timeout(timeout);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	finish_wait(wq, &wait);
-- 
2.51.0

[FOR CI 4/5] drm/i915/display: Disable interrupts on xe for realtime preemption

[Maarten Lankhorst]

Check if it works at all, and then see what the timing results are.

Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/display/intel_crtc.c   | 12 +++++++-----
 drivers/gpu/drm/i915/display/intel_vblank.c |  4 ++--
 drivers/gpu/drm/i915/display/intel_vblank.h |  9 +++++++++
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index f34745b5ea497..39a4ff902e6ce 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -567,7 +567,7 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	 */
 	intel_psr_wait_for_idle_locked(new_crtc_state);
 
-	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+	if (intel_disable_vblank_irqs())
 		local_irq_disable();
 
 	crtc->debug.min_vbl = evade.min;
@@ -586,7 +586,7 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	return;
 
 irq_disable:
-	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+	if (intel_disable_vblank_irqs())
 		local_irq_disable();
 }
 
@@ -686,6 +686,10 @@ 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);
 
+	preempt_disable();
+        if (intel_disable_vblank_irqs())
+		local_irq_enable();
+
 	/* 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
@@ -733,9 +737,7 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
 	if (!state->base.legacy_cursor_update)
 		intel_vrr_send_push(NULL, new_crtc_state);
 
-	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
-		local_irq_enable();
-
+	preempt_enable();
 	if (intel_vgpu_active(dev_priv))
 		goto out;
 
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index 7826f29619a14..09be26f6a3df8 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -761,12 +761,12 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade)
 			break;
 		}
 
-		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		if (intel_disable_vblank_irqs())
 			local_irq_enable();
 
 		timeout = schedule_timeout(timeout);
 
-		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		if (intel_disable_vblank_irqs())
 			local_irq_disable();
 	}
 
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.h b/drivers/gpu/drm/i915/display/intel_vblank.h
index 98d04cacd65f8..7207dcf7e1c5e 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.h
+++ b/drivers/gpu/drm/i915/display/intel_vblank.h
@@ -50,4 +50,13 @@ intel_pre_commit_crtc_state(struct intel_atomic_state *state,
 
 int intel_crtc_vblank_length(const struct intel_crtc_state *crtc_state);
 
+static inline int intel_disable_vblank_irqs(void)
+{
+#if !defined(I915) && !IS_ENABLED(CONFIG_PREEMPT_RT)
+	return true;
+#else
+	return false;
+#endif
+}
+
 #endif /* __INTEL_VBLANK_H__ */
-- 
2.51.0

[FOR CI 5/5] [FOR-CI] PREEMPT_RT injection

[Maarten Lankhorst]

Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/Kconfig.debug | 15 ---------------
 drivers/gpu/drm/xe/Kconfig.debug   |  5 +++++
 kernel/Kconfig.preempt             |  3 +--
 3 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
index 3562a02ef7adc..0ab10ff41e38d 100644
--- a/drivers/gpu/drm/i915/Kconfig.debug
+++ b/drivers/gpu/drm/i915/Kconfig.debug
@@ -233,21 +233,6 @@ config DRM_I915_LOW_LEVEL_TRACEPOINTS
 
 	  If in doubt, say "N".
 
-config DRM_I915_DEBUG_VBLANK_EVADE
-	bool "Enable extra debug warnings for vblank evasion"
-	depends on DRM_I915
-	default n
-	help
-	  Choose this option to turn on extra debug warnings for the
-	  vblank evade mechanism. This gives a warning every time the
-	  the deadline allotted for the vblank evade critical section
-	  is exceeded, even if there isn't an actual risk of missing
-	  the vblank.
-
-	  Recommended for driver developers only.
-
-	  If in doubt, say "N".
-
 config DRM_I915_DEBUG_RUNTIME_PM
 	bool "Enable extra state checking for runtime PM"
 	depends on DRM_I915
diff --git a/drivers/gpu/drm/xe/Kconfig.debug b/drivers/gpu/drm/xe/Kconfig.debug
index 01227c77f6d70..1d5f11c6e88f3 100644
--- a/drivers/gpu/drm/xe/Kconfig.debug
+++ b/drivers/gpu/drm/xe/Kconfig.debug
@@ -30,6 +30,11 @@ config DRM_XE_DEBUG
 
 	  If in doubt, say "N".
 
+config DRM_I915_DEBUG_VBLANK_EVADE
+        def_bool y
+        depends on DRM_XE
+
+
 config DRM_XE_DEBUG_VM
 	bool "Enable extra VM debugging info"
 	default n
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index da326800c1c9b..5e5bba2fd0e9a 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -87,8 +87,7 @@ config PREEMPT_LAZY
 endchoice
 
 config PREEMPT_RT
-	bool "Fully Preemptible Kernel (Real-Time)"
-	depends on EXPERT && ARCH_SUPPORTS_RT && !COMPILE_TEST
+	def_bool y
 	select PREEMPTION
 	help
 	  This option turns the kernel into a real-time kernel by replacing
-- 
2.51.0

✗ CI.checkpatch: warning for Testing PREEMPT_RT with disabling interrupts in the most critical section.

[Patchwork]

== Series Details ==

Series: Testing PREEMPT_RT with disabling interrupts in the most critical section.
URL   : https://patchwork.freedesktop.org/series/156134/
State : warning

== Summary ==

+ KERNEL=/kernel
+ git clone https://gitlab.freedesktop.org/drm/maintainer-tools mt
Cloning into 'mt'...
warning: redirecting to https://gitlab.freedesktop.org/drm/maintainer-tools.git/
+ git -C mt rev-list -n1 origin/master
fbd08a78c3a3bb17964db2a326514c69c1dca660
+ cd /kernel
+ git config --global --add safe.directory /kernel
+ git log -n1
commit 750bd54e8a8317d7e60916aa89ca790d949a4ee6
Author: Maarten Lankhorst <dev@lankhorst.se>
Date:   Fri Oct 17 17:37:48 2025 +0200

    PREEMPT_RT injection
    
    Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
+ /mt/dim checkpatch b5e5976a35cb0e8e45aea836b42ecccf22df803f drm-intel
1f74491ecafc drm/xe: Bump xe_device_l2_flush even higher
cd53ffd9ad75 drm/i915: Use preempt_disable/enable_rt() where recommended
-:7: WARNING:COMMIT_LOG_LONG_LINE: Prefer a maximum 75 chars per line (possible unwrapped commit description?)
#7: 
  ad3543ede630f ("drm/intel: Push get_scanout_position() timestamping into kms driver.")

-:45: WARNING:LINE_SPACING: Missing a blank line after declarations
#45: FILE: drivers/gpu/drm/i915/display/intel_vblank.c:323:
+	struct drm_i915_private *i915 = to_i915(display->drm);
+	spin_lock_irqsave(&i915->uncore.lock, *flags);

-:52: WARNING:LINE_SPACING: Missing a blank line after declarations
#52: FILE: drivers/gpu/drm/i915/display/intel_vblank.c:330:
+	struct drm_i915_private *i915 = to_i915(display->drm);
+	spin_unlock_irqrestore(&i915->uncore.lock, flags);

total: 0 errors, 3 warnings, 0 checks, 78 lines checked
d0c62abf4505 drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates
-:10: WARNING:COMMIT_LOG_LONG_LINE: Prefer a maximum 75 chars per line (possible unwrapped commit description?)
#10: 
started disabling interrupts across atomic updates. This breaks on PREEMPT_RT

total: 0 errors, 1 warnings, 0 checks, 68 lines checked
25cad8154ec0 drm/i915/display: Disable interrupts on xe for realtime preemption
-:38: ERROR:CODE_INDENT: code indent should use tabs where possible
#38: FILE: drivers/gpu/drm/i915/display/intel_crtc.c:690:
+        if (intel_disable_vblank_irqs())$

-:38: WARNING:LEADING_SPACE: please, no spaces at the start of a line
#38: FILE: drivers/gpu/drm/i915/display/intel_crtc.c:690:
+        if (intel_disable_vblank_irqs())$

total: 1 errors, 1 warnings, 0 checks, 63 lines checked
750bd54e8a83 PREEMPT_RT injection
-:7: WARNING:COMMIT_MESSAGE: Missing commit description - Add an appropriate one

total: 0 errors, 1 warnings, 0 checks, 41 lines checked

✗ CI.KUnit: failure for Testing PREEMPT_RT with disabling interrupts in the most critical section.

[Patchwork]

== Series Details ==

Series: Testing PREEMPT_RT with disabling interrupts in the most critical section.
URL   : https://patchwork.freedesktop.org/series/156134/
State : failure

== Summary ==

+ trap cleanup EXIT
+ /kernel/tools/testing/kunit/kunit.py run --kunitconfig /kernel/drivers/gpu/drm/xe/.kunitconfig
ERROR:root:Not all Kconfig options selected in kunitconfig were in the generated .config.
This is probably due to unsatisfied dependencies.
Missing: CONFIG_DEBUG_MUTEXES=y, # CONFIG_DRM_XE_DISPLAY is not set
Note: many Kconfig options aren't available on UML. You can try running on a different architecture with something like "--arch=x86_64".
[16:37:35] Configuring KUnit Kernel ...
Generating .config ...
Populating config with:
$ make ARCH=um O=.kunit olddefconfig
+ cleanup
++ stat -c %u:%g /kernel
+ chown -R 1003:1003 /kernel

[FOR CI 0/5] Testing PREEMPT_RT with disabling preemption in the most critical section.

[Maarten Lankhorst]

Fix get_vblank_counter() and try to disable preemption in the most critical part of the code.

Maarten Lankhorst (3):
  drm/i915/display: Make get_vblank_counter use intel_de_read_fw()
  drm/xe/display: Disable preemption in the most critical section
  PREEMPT_RT injection

Mike Galbraith (2):
  drm/i915: Use preempt_disable/enable_rt() where recommended
  drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

 drivers/gpu/drm/i915/Kconfig.debug          | 15 ----
 drivers/gpu/drm/i915/display/intel_crtc.c   | 23 +++++-
 drivers/gpu/drm/i915/display/intel_cursor.c | 27 ++++++-
 drivers/gpu/drm/i915/display/intel_vblank.c | 90 ++++++++++++++-------
 drivers/gpu/drm/xe/Kconfig.debug            |  5 ++
 kernel/Kconfig.preempt                      |  4 +-
 6 files changed, 111 insertions(+), 53 deletions(-)

-- 
2.51.0

[FOR CI 3/5] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

[Maarten Lankhorst]

From: Mike Galbraith <umgwanakikbuti@gmail.com>

Commit
   8d7849db3eab7 ("drm/i915: Make sprite updates atomic")

started disabling interrupts across atomic updates. This breaks on PREEMPT_RT
because within this section the code attempt to acquire spinlock_t locks which
are sleeping locks on PREEMPT_RT.

According to the comment the interrupts are disabled to avoid random delays and
not required for protection or synchronisation.
If this needs to happen with disabled interrupts on PREEMPT_RT, and the
whole section is restricted to register access then all sleeping locks
need to be acquired before interrupts are disabled and some function
maybe moved after enabling interrupts again.
This includes:
- prepare_to_wait() + finish_wait() due its wake queue.
- drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock.
- skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and
  maybe others due to intel_uncore::lock
- drm_crtc_arm_vblank_event() due to drm_device::event_lock and
  drm_device::vblank_time_lock.

Don't disable interrupts on PREEMPT_RT during atomic updates.

[bigeasy: drop local locks, commit message]

Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/display/intel_crtc.c   | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_cursor.c | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_vblank.c | 6 ++++--
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index d300ba1dcd2c4..f34745b5ea497 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -567,7 +567,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	 */
 	intel_psr_wait_for_idle_locked(new_crtc_state);
 
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 
 	crtc->debug.min_vbl = evade.min;
 	crtc->debug.max_vbl = evade.max;
@@ -585,7 +586,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	return;
 
 irq_disable:
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE)
@@ -731,7 +733,8 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
 	if (!state->base.legacy_cursor_update)
 		intel_vrr_send_push(NULL, new_crtc_state);
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	if (intel_vgpu_active(dev_priv))
 		goto out;
diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index c47c849358714..780fcae77a984 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -919,13 +919,15 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		 */
 		intel_psr_wait_for_idle_locked(crtc_state);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 
 		intel_vblank_evade(&evade);
 
 		drm_crtc_vblank_put(&crtc->base);
 	} else {
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	if (new_plane_state->uapi.visible) {
@@ -935,7 +937,8 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		intel_plane_disable_arm(NULL, plane, crtc_state);
 	}
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	intel_psr_unlock(crtc_state);
 
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index cd7f2c1ef21af..cb060b5c04659 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -761,11 +761,13 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade)
 			break;
 		}
 
-		local_irq_enable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_enable();
 
 		timeout = schedule_timeout(timeout);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	finish_wait(wq, &wait);
-- 
2.51.0

[FOR CI 0/5] drm/xe/display: Test series with PREEMPT_RT and preemption disable.

[Maarten Lankhorst]

Fixing the issues with waiting from the previous version.

Maarten Lankhorst (3):
  drm/xe: Bump xe_device_l2_flush even higher
  drm/xe/display: Disable preemption in the most critical section
  PREEMPT_RT injection

Mike Galbraith (2):
  drm/i915: Use preempt_disable/enable_rt() where recommended
  drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

 drivers/gpu/drm/i915/Kconfig.debug          | 15 ----
 drivers/gpu/drm/i915/display/intel_crtc.c   | 23 +++++-
 drivers/gpu/drm/i915/display/intel_cursor.c | 27 ++++++-
 drivers/gpu/drm/i915/display/intel_vblank.c | 88 ++++++++++++++-------
 drivers/gpu/drm/xe/Kconfig.debug            |  5 ++
 drivers/gpu/drm/xe/xe_device.c              |  4 +-
 kernel/Kconfig.preempt                      |  4 +-
 7 files changed, 112 insertions(+), 54 deletions(-)

-- 
2.51.0

[FOR CI 3/5] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

[Maarten Lankhorst]

From: Mike Galbraith <umgwanakikbuti@gmail.com>

Commit
   8d7849db3eab7 ("drm/i915: Make sprite updates atomic")

started disabling interrupts across atomic updates. This breaks on PREEMPT_RT
because within this section the code attempt to acquire spinlock_t locks which
are sleeping locks on PREEMPT_RT.

According to the comment the interrupts are disabled to avoid random delays and
not required for protection or synchronisation.
If this needs to happen with disabled interrupts on PREEMPT_RT, and the
whole section is restricted to register access then all sleeping locks
need to be acquired before interrupts are disabled and some function
maybe moved after enabling interrupts again.
This includes:
- prepare_to_wait() + finish_wait() due its wake queue.
- drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock.
- skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and
  maybe others due to intel_uncore::lock
- drm_crtc_arm_vblank_event() due to drm_device::event_lock and
  drm_device::vblank_time_lock.

Don't disable interrupts on PREEMPT_RT during atomic updates.

[bigeasy: drop local locks, commit message]

Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/display/intel_crtc.c   | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_cursor.c | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_vblank.c | 6 ++++--
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index d300ba1dcd2c4..f34745b5ea497 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -567,7 +567,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	 */
 	intel_psr_wait_for_idle_locked(new_crtc_state);
 
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 
 	crtc->debug.min_vbl = evade.min;
 	crtc->debug.max_vbl = evade.max;
@@ -585,7 +586,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	return;
 
 irq_disable:
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE)
@@ -731,7 +733,8 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
 	if (!state->base.legacy_cursor_update)
 		intel_vrr_send_push(NULL, new_crtc_state);
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	if (intel_vgpu_active(dev_priv))
 		goto out;
diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index c47c849358714..780fcae77a984 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -919,13 +919,15 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		 */
 		intel_psr_wait_for_idle_locked(crtc_state);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 
 		intel_vblank_evade(&evade);
 
 		drm_crtc_vblank_put(&crtc->base);
 	} else {
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	if (new_plane_state->uapi.visible) {
@@ -935,7 +937,8 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		intel_plane_disable_arm(NULL, plane, crtc_state);
 	}
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	intel_psr_unlock(crtc_state);
 
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index 5206a81f85554..7826f29619a14 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -761,11 +761,13 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade)
 			break;
 		}
 
-		local_irq_enable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_enable();
 
 		timeout = schedule_timeout(timeout);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	finish_wait(wq, &wait);
-- 
2.51.0

[FOR CI 0/5] Testing PREEMPT_RT with disabling interrupts in the most critical section.

[Maarten Lankhorst]

Only disable preemption in this series.

Maarten Lankhorst (3):
  drm/xe: Bump xe_device_l2_flush even higher
  drm/xe/display: Disable preemption in the most critical section
  PREEMPT_RT injection

Mike Galbraith (2):
  drm/i915: Use preempt_disable/enable_rt() where recommended
  drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

 drivers/gpu/drm/i915/Kconfig.debug          | 15 ----
 drivers/gpu/drm/i915/display/intel_crtc.c   | 23 +++++-
 drivers/gpu/drm/i915/display/intel_cursor.c | 27 ++++++-
 drivers/gpu/drm/i915/display/intel_vblank.c | 81 ++++++++++++++-------
 drivers/gpu/drm/xe/Kconfig.debug            |  5 ++
 drivers/gpu/drm/xe/xe_device.c              |  4 +-
 kernel/Kconfig.preempt                      |  4 +-
 7 files changed, 108 insertions(+), 51 deletions(-)

-- 
2.51.0

[FOR CI 3/5] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

[Maarten Lankhorst]

From: Mike Galbraith <umgwanakikbuti@gmail.com>

Commit
   8d7849db3eab7 ("drm/i915: Make sprite updates atomic")

started disabling interrupts across atomic updates. This breaks on PREEMPT_RT
because within this section the code attempt to acquire spinlock_t locks which
are sleeping locks on PREEMPT_RT.

According to the comment the interrupts are disabled to avoid random delays and
not required for protection or synchronisation.
If this needs to happen with disabled interrupts on PREEMPT_RT, and the
whole section is restricted to register access then all sleeping locks
need to be acquired before interrupts are disabled and some function
maybe moved after enabling interrupts again.
This includes:
- prepare_to_wait() + finish_wait() due its wake queue.
- drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock.
- skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and
  maybe others due to intel_uncore::lock
- drm_crtc_arm_vblank_event() due to drm_device::event_lock and
  drm_device::vblank_time_lock.

Don't disable interrupts on PREEMPT_RT during atomic updates.

[bigeasy: drop local locks, commit message]

Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/display/intel_crtc.c   | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_cursor.c | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_vblank.c | 6 ++++--
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index d300ba1dcd2c4..f34745b5ea497 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -567,7 +567,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	 */
 	intel_psr_wait_for_idle_locked(new_crtc_state);
 
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 
 	crtc->debug.min_vbl = evade.min;
 	crtc->debug.max_vbl = evade.max;
@@ -585,7 +586,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	return;
 
 irq_disable:
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE)
@@ -731,7 +733,8 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
 	if (!state->base.legacy_cursor_update)
 		intel_vrr_send_push(NULL, new_crtc_state);
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	if (intel_vgpu_active(dev_priv))
 		goto out;
diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index c47c849358714..780fcae77a984 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -919,13 +919,15 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		 */
 		intel_psr_wait_for_idle_locked(crtc_state);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 
 		intel_vblank_evade(&evade);
 
 		drm_crtc_vblank_put(&crtc->base);
 	} else {
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	if (new_plane_state->uapi.visible) {
@@ -935,7 +937,8 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		intel_plane_disable_arm(NULL, plane, crtc_state);
 	}
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	intel_psr_unlock(crtc_state);
 
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index 5206a81f85554..7826f29619a14 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -761,11 +761,13 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade)
 			break;
 		}
 
-		local_irq_enable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_enable();
 
 		timeout = schedule_timeout(timeout);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	finish_wait(wq, &wait);
-- 
2.51.0

[FOR CI 0/5] drm/xe/display: Test series with PREEMPT_RT and preemption disable.

[Maarten Lankhorst]

Keep interrupts enabled, see what happens...

Maarten Lankhorst (3):
  drm/xe: Bump xe_device_l2_flush even higher
  drm/xe/display: Disable preemption in the most critical section
  PREEMPT_RT injection

Mike Galbraith (2):
  drm/i915: Use preempt_disable/enable_rt() where recommended
  drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

 drivers/gpu/drm/i915/Kconfig.debug          | 15 ------
 drivers/gpu/drm/i915/display/intel_crtc.c   | 23 ++++++--
 drivers/gpu/drm/i915/display/intel_cursor.c | 27 ++++++++--
 drivers/gpu/drm/i915/display/intel_vblank.c | 58 ++++++++++++++++-----
 drivers/gpu/drm/xe/Kconfig.debug            |  5 ++
 drivers/gpu/drm/xe/xe_device.c              |  4 +-
 kernel/Kconfig.preempt                      |  4 +-
 7 files changed, 97 insertions(+), 39 deletions(-)

-- 
2.51.0

[FOR CI 3/5] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

[Maarten Lankhorst]

From: Mike Galbraith <umgwanakikbuti@gmail.com>

Commit
   8d7849db3eab7 ("drm/i915: Make sprite updates atomic")

started disabling interrupts across atomic updates. This breaks on PREEMPT_RT
because within this section the code attempt to acquire spinlock_t locks which
are sleeping locks on PREEMPT_RT.

According to the comment the interrupts are disabled to avoid random delays and
not required for protection or synchronisation.
If this needs to happen with disabled interrupts on PREEMPT_RT, and the
whole section is restricted to register access then all sleeping locks
need to be acquired before interrupts are disabled and some function
maybe moved after enabling interrupts again.
This includes:
- prepare_to_wait() + finish_wait() due its wake queue.
- drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock.
- skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and
  maybe others due to intel_uncore::lock
- drm_crtc_arm_vblank_event() due to drm_device::event_lock and
  drm_device::vblank_time_lock.

Don't disable interrupts on PREEMPT_RT during atomic updates.

[bigeasy: drop local locks, commit message]

Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/display/intel_crtc.c   | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_cursor.c | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_vblank.c | 6 ++++--
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index d300ba1dcd2c4..f34745b5ea497 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -567,7 +567,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	 */
 	intel_psr_wait_for_idle_locked(new_crtc_state);
 
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 
 	crtc->debug.min_vbl = evade.min;
 	crtc->debug.max_vbl = evade.max;
@@ -585,7 +586,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	return;
 
 irq_disable:
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE)
@@ -731,7 +733,8 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
 	if (!state->base.legacy_cursor_update)
 		intel_vrr_send_push(NULL, new_crtc_state);
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	if (intel_vgpu_active(dev_priv))
 		goto out;
diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index c47c849358714..780fcae77a984 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -919,13 +919,15 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		 */
 		intel_psr_wait_for_idle_locked(crtc_state);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 
 		intel_vblank_evade(&evade);
 
 		drm_crtc_vblank_put(&crtc->base);
 	} else {
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	if (new_plane_state->uapi.visible) {
@@ -935,7 +937,8 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		intel_plane_disable_arm(NULL, plane, crtc_state);
 	}
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	intel_psr_unlock(crtc_state);
 
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index 5206a81f85554..7826f29619a14 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -761,11 +761,13 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade)
 			break;
 		}
 
-		local_irq_enable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_enable();
 
 		timeout = schedule_timeout(timeout);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	finish_wait(wq, &wait);
-- 
2.51.0

[FOR CI 0/5] drm/xe/display: Disable migration for the critical

[Maarten Lankhorst]

Using the principle of minimal impact to latency possible, only prevent migration
from occurring first.

Maarten Lankhorst (3):
  drm/xe: Bump xe_device_l2_flush even higher
  drm/xe/display: Disable migration in the most critical section
  [FOR-CI] PREEMPT_RT injection

Mike Galbraith (2):
  drm/i915: Use preempt_disable/enable_rt() where recommended
  drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

 drivers/gpu/drm/i915/Kconfig.debug          | 15 ------
 drivers/gpu/drm/i915/display/intel_crtc.c   | 23 ++++++--
 drivers/gpu/drm/i915/display/intel_cursor.c | 27 ++++++++--
 drivers/gpu/drm/i915/display/intel_dmc.c    |  4 +-
 drivers/gpu/drm/i915/display/intel_vblank.c | 58 ++++++++++++++++-----
 drivers/gpu/drm/xe/Kconfig.debug            |  5 ++
 drivers/gpu/drm/xe/xe_device.c              |  4 +-
 kernel/Kconfig.preempt                      |  3 +-
 8 files changed, 98 insertions(+), 41 deletions(-)

-- 
2.51.0

[FOR CI 3/5] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

[Maarten Lankhorst]

From: Mike Galbraith <umgwanakikbuti@gmail.com>

Commit
   8d7849db3eab7 ("drm/i915: Make sprite updates atomic")

started disabling interrupts across atomic updates. This breaks on PREEMPT_RT
because within this section the code attempt to acquire spinlock_t locks which
are sleeping locks on PREEMPT_RT.

According to the comment the interrupts are disabled to avoid random delays and
not required for protection or synchronisation.
If this needs to happen with disabled interrupts on PREEMPT_RT, and the
whole section is restricted to register access then all sleeping locks
need to be acquired before interrupts are disabled and some function
maybe moved after enabling interrupts again.
This includes:
- prepare_to_wait() + finish_wait() due its wake queue.
- drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock.
- skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and
  maybe others due to intel_uncore::lock
- drm_crtc_arm_vblank_event() due to drm_device::event_lock and
  drm_device::vblank_time_lock.

Don't disable interrupts on PREEMPT_RT during atomic updates.

[bigeasy: drop local locks, commit message]

Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/display/intel_crtc.c   | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_cursor.c | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_vblank.c | 6 ++++--
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index d300ba1dcd2c4..f34745b5ea497 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -567,7 +567,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	 */
 	intel_psr_wait_for_idle_locked(new_crtc_state);
 
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 
 	crtc->debug.min_vbl = evade.min;
 	crtc->debug.max_vbl = evade.max;
@@ -585,7 +586,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	return;
 
 irq_disable:
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE)
@@ -731,7 +733,8 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
 	if (!state->base.legacy_cursor_update)
 		intel_vrr_send_push(NULL, new_crtc_state);
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	if (intel_vgpu_active(dev_priv))
 		goto out;
diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index c47c849358714..780fcae77a984 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -919,13 +919,15 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		 */
 		intel_psr_wait_for_idle_locked(crtc_state);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 
 		intel_vblank_evade(&evade);
 
 		drm_crtc_vblank_put(&crtc->base);
 	} else {
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	if (new_plane_state->uapi.visible) {
@@ -935,7 +937,8 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		intel_plane_disable_arm(NULL, plane, crtc_state);
 	}
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	intel_psr_unlock(crtc_state);
 
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index 5206a81f85554..7826f29619a14 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -761,11 +761,13 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade)
 			break;
 		}
 
-		local_irq_enable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_enable();
 
 		timeout = schedule_timeout(timeout);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	finish_wait(wq, &wait);
-- 
2.51.0

[FOR CI 0/5] Test PREEMPT_RT with irqs disabled.

[Maarten Lankhorst]

Just a quick check to see if PREEMPT_RT runs into any issues without
IRQs.

Maarten Lankhorst (3):
  drm/xe: Bump xe_device_l2_flush even higher
  drm/i915/display: Disable interrupts on xe for realtime preemption
  [FOR-CI] PREEMPT_RT injection

Mike Galbraith (2):
  drm/i915: Use preempt_disable/enable_rt() where recommended
  drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

 drivers/gpu/drm/i915/Kconfig.debug          | 15 -------
 drivers/gpu/drm/i915/display/intel_crtc.c   | 13 ++++--
 drivers/gpu/drm/i915/display/intel_cursor.c |  9 ++--
 drivers/gpu/drm/i915/display/intel_vblank.c | 49 ++++++++++++++++-----
 drivers/gpu/drm/i915/display/intel_vblank.h |  9 ++++
 drivers/gpu/drm/xe/Kconfig.debug            |  5 +++
 drivers/gpu/drm/xe/xe_device.c              |  4 +-
 kernel/Kconfig.preempt                      |  3 +-
 8 files changed, 69 insertions(+), 38 deletions(-)

-- 
2.51.0

[FOR CI 3/5] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates

[Maarten Lankhorst]

From: Mike Galbraith <umgwanakikbuti@gmail.com>

Commit
   8d7849db3eab7 ("drm/i915: Make sprite updates atomic")

started disabling interrupts across atomic updates. This breaks on PREEMPT_RT
because within this section the code attempt to acquire spinlock_t locks which
are sleeping locks on PREEMPT_RT.

According to the comment the interrupts are disabled to avoid random delays and
not required for protection or synchronisation.
If this needs to happen with disabled interrupts on PREEMPT_RT, and the
whole section is restricted to register access then all sleeping locks
need to be acquired before interrupts are disabled and some function
maybe moved after enabling interrupts again.
This includes:
- prepare_to_wait() + finish_wait() due its wake queue.
- drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock.
- skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and
  maybe others due to intel_uncore::lock
- drm_crtc_arm_vblank_event() due to drm_device::event_lock and
  drm_device::vblank_time_lock.

Don't disable interrupts on PREEMPT_RT during atomic updates.

[bigeasy: drop local locks, commit message]

Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
---
 drivers/gpu/drm/i915/display/intel_crtc.c   | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_cursor.c | 9 ++++++---
 drivers/gpu/drm/i915/display/intel_vblank.c | 6 ++++--
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index d300ba1dcd2c4..f34745b5ea497 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -567,7 +567,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	 */
 	intel_psr_wait_for_idle_locked(new_crtc_state);
 
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 
 	crtc->debug.min_vbl = evade.min;
 	crtc->debug.max_vbl = evade.max;
@@ -585,7 +586,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state,
 	return;
 
 irq_disable:
-	local_irq_disable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_disable();
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE)
@@ -731,7 +733,8 @@ void intel_pipe_update_end(struct intel_atomic_state *state,
 	if (!state->base.legacy_cursor_update)
 		intel_vrr_send_push(NULL, new_crtc_state);
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	if (intel_vgpu_active(dev_priv))
 		goto out;
diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c
index c47c849358714..780fcae77a984 100644
--- a/drivers/gpu/drm/i915/display/intel_cursor.c
+++ b/drivers/gpu/drm/i915/display/intel_cursor.c
@@ -919,13 +919,15 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		 */
 		intel_psr_wait_for_idle_locked(crtc_state);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 
 		intel_vblank_evade(&evade);
 
 		drm_crtc_vblank_put(&crtc->base);
 	} else {
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	if (new_plane_state->uapi.visible) {
@@ -935,7 +937,8 @@ intel_legacy_cursor_update(struct drm_plane *_plane,
 		intel_plane_disable_arm(NULL, plane, crtc_state);
 	}
 
-	local_irq_enable();
+	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+		local_irq_enable();
 
 	intel_psr_unlock(crtc_state);
 
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c
index 5206a81f85554..7826f29619a14 100644
--- a/drivers/gpu/drm/i915/display/intel_vblank.c
+++ b/drivers/gpu/drm/i915/display/intel_vblank.c
@@ -761,11 +761,13 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade)
 			break;
 		}
 
-		local_irq_enable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_enable();
 
 		timeout = schedule_timeout(timeout);
 
-		local_irq_disable();
+		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+			local_irq_disable();
 	}
 
 	finish_wait(wq, &wait);
-- 
2.51.0