diff options
| author | Mike Galbraith <umgwanakikbuti@gmail.com> | 2016-02-27 10:09:11 +0300 |
|---|---|---|
| committer | Minda Chen <minda.chen@starfivetech.com> | 2023-11-06 14:24:48 +0300 |
| commit | e70229b22b0795c980944e36029c2aaf6806f644 (patch) | |
| tree | 212185a853165d2a95f04624f68ca8276ee7310a | |
| parent | 488af98016013872f49435c01f93e15edffdcbc4 (diff) | |
| download | linux-e70229b22b0795c980944e36029c2aaf6806f644.tar.xz | |
drm/i915: Use preempt_disable/enable_rt() where recommended
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>
| -rw-r--r-- | drivers/gpu/drm/i915/i915_irq.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 9bc4f4a8e12e..547347241a47 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -886,7 +886,8 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, */ 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) @@ -950,7 +951,8 @@ 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(); spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags); |