diff options
Diffstat (limited to 'debian/patches-rt/0003-drm-i915-Use-preempt_disable-enable_rt-where-recomme.patch')
| -rw-r--r-- | debian/patches-rt/0003-drm-i915-Use-preempt_disable-enable_rt-where-recomme.patch | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/debian/patches-rt/0003-drm-i915-Use-preempt_disable-enable_rt-where-recomme.patch b/debian/patches-rt/0003-drm-i915-Use-preempt_disable-enable_rt-where-recomme.patch new file mode 100644 index 000000000..f2752d090 --- /dev/null +++ b/debian/patches-rt/0003-drm-i915-Use-preempt_disable-enable_rt-where-recomme.patch @@ -0,0 +1,56 @@ +From: Mike Galbraith <umgwanakikbuti@gmail.com> +Date: Sat, 27 Feb 2016 08:09:11 +0100 +Subject: [PATCH 03/10] drm/i915: Use preempt_disable/enable_rt() where + recommended +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz + +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> +--- + drivers/gpu/drm/i915/display/intel_vblank.c | 6 ++++-- + 1 file changed, 4 insertions(+), 2 deletions(-) + +--- a/drivers/gpu/drm/i915/display/intel_vblank.c ++++ b/drivers/gpu/drm/i915/display/intel_vblank.c +@@ -294,7 +294,8 @@ static bool i915_get_crtc_scanoutpos(str + */ + spin_lock_irqsave(&dev_priv->uncore.lock, 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) +@@ -358,7 +359,8 @@ static bool i915_get_crtc_scanoutpos(str + if (etime) + *etime = ktime_get(); + +- /* preempt_enable_rt() should go right here in PREEMPT_RT patchset. */ ++ if (IS_ENABLED(CONFIG_PREEMPT_RT)) ++ preempt_enable(); + + spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags); + |