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-rw-r--r--debian/patches-rt/0025-drm-i915-Don-t-check-for-atomic-context-on-PREEMPT_R.patch36
1 files changed, 36 insertions, 0 deletions
diff --git a/debian/patches-rt/0025-drm-i915-Don-t-check-for-atomic-context-on-PREEMPT_R.patch b/debian/patches-rt/0025-drm-i915-Don-t-check-for-atomic-context-on-PREEMPT_R.patch
new file mode 100644
index 000000000..2bbcdfed9
--- /dev/null
+++ b/debian/patches-rt/0025-drm-i915-Don-t-check-for-atomic-context-on-PREEMPT_R.patch
@@ -0,0 +1,36 @@
+From d9970290d810087f44a37de7ae6f3638ecddd3a0 Mon Sep 17 00:00:00 2001
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Mon, 25 Oct 2021 15:05:18 +0200
+Subject: [PATCH 25/62] drm/i915: Don't check for atomic context on PREEMPT_RT
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.1/older/patches-6.1.69-rt21.tar.xz
+
+The !in_atomic() check in _wait_for_atomic() triggers on PREEMPT_RT
+because the uncore::lock is a spinlock_t and does not disable
+preemption or interrupts.
+
+Changing the uncore:lock to a raw_spinlock_t doubles the worst case
+latency on an otherwise idle testbox during testing. Therefore I'm
+currently unsure about changing this.
+
+Link: https://lore.kernel.org/all/20211006164628.s2mtsdd2jdbfyf7g@linutronix.de/
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ drivers/gpu/drm/i915/i915_utils.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
+index 6c14d13364bf..de58855e6926 100644
+--- a/drivers/gpu/drm/i915/i915_utils.h
++++ b/drivers/gpu/drm/i915/i915_utils.h
+@@ -294,7 +294,7 @@ wait_remaining_ms_from_jiffies(unsigned long timestamp_jiffies, int to_wait_ms)
+ #define wait_for(COND, MS) _wait_for((COND), (MS) * 1000, 10, 1000)
+
+ /* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */
+-#if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT)
++#if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT) && !defined(CONFIG_PREEMPT_RT)
+ # define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) WARN_ON_ONCE((ATOMIC) && !in_atomic())
+ #else
+ # define _WAIT_FOR_ATOMIC_CHECK(ATOMIC) do { } while (0)
+--
+2.43.0
+