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drm/i915: Clarify event_lock locking, irq&mixed context

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Now we tackle the functions also called from interrupt handlers.

- intel_check_page_flip is exclusively called from irq handlers, so a
  plain spin_lock is all we need. In i915_irq.c we have the convention
  to give all such functions an _irq_handler postfix, but that would
  look strange and als be a bit a misleading name. I've opted for a
  WARN_ON(!in_irq()) instead.

- The other two places left are called both from interrupt handlers
  and from our reset work, so need the full irqsave dance. Annotate
  them with a short comment.

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2014-09-15 14:55:23 +02:00
parent 5e2d7afcfe
commit f326038a29
1 changed files with 14 additions and 4 deletions
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18
drivers/gpu/drm/i915/intel_display.c
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@ -9328,6 +9328,10 @@ static void do_intel_finish_page_flip(struct drm_device *dev,
if (intel_crtc == NULL)
return;
/*
* This is called both by irq handlers and the reset code (to complete
* lost pageflips) so needs the full irqsave spinlocks.
*/
spin_lock_irqsave(&dev->event_lock, flags);
work = intel_crtc->unpin_work;
@ -9409,7 +9413,12 @@ void intel_prepare_page_flip(struct drm_device *dev, int plane)
to_intel_crtc(dev_priv->plane_to_crtc_mapping[plane]);
unsigned long flags;
/* NB: An MMIO update of the plane base pointer will also
/*
* This is called both by irq handlers and the reset code (to complete
* lost pageflips) so needs the full irqsave spinlocks.
*
* NB: An MMIO update of the plane base pointer will also
* generate a page-flip completion irq, i.e. every modeset
* is also accompanied by a spurious intel_prepare_page_flip().
*/
@ -9866,18 +9875,19 @@ void intel_check_page_flip(struct drm_device *dev, int pipe)
struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_crtc *crtc = dev_priv->pipe_to_crtc_mapping[pipe];
struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
unsigned long flags;
WARN_ON(!in_irq());
if (crtc == NULL)
return;
spin_lock_irqsave(&dev->event_lock, flags);
spin_lock(&dev->event_lock);
if (intel_crtc->unpin_work && __intel_pageflip_stall_check(dev, crtc)) {
WARN_ONCE(1, "Kicking stuck page flip: queued at %d, now %d\n",
intel_crtc->unpin_work->flip_queued_vblank, drm_vblank_count(dev, pipe));
page_flip_completed(intel_crtc);
}
spin_unlock_irqrestore(&dev->event_lock, flags);
spin_unlock(&dev->event_lock);
}
static int intel_crtc_page_flip(struct drm_crtc *crtc,