drm/i915: optimize ilk/snb irq handler
We only need to read/write the south interrupt register if the
corresponding bit is set in the north master interrupt register.
Noticed while reading our interrupt handling code.
Same optimization has already been applied on ivb in
commit 0e43406bcc1868a316eea6012a0a09d992c53521
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed May 9 21:45:44 2012 +0100
drm/i915: Simplify interrupt processing for IvyBridge
We can take advantage that the PCH_IIR is a subordinate register to
reduce one of the required IIR reads, and that we only need to clear
interrupts handled to reduce the writes. And by simply tidying the code
we can reduce the line count and hopefully make it more readable.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 6cd3dc9..26753ee 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -758,7 +758,7 @@
struct drm_device *dev = (struct drm_device *) arg;
drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private;
int ret = IRQ_NONE;
- u32 de_iir, gt_iir, de_ier, pch_iir, pm_iir;
+ u32 de_iir, gt_iir, de_ier, pm_iir;
atomic_inc(&dev_priv->irq_received);
@@ -769,11 +769,9 @@
de_iir = I915_READ(DEIIR);
gt_iir = I915_READ(GTIIR);
- pch_iir = I915_READ(SDEIIR);
pm_iir = I915_READ(GEN6_PMIIR);
- if (de_iir == 0 && gt_iir == 0 && pch_iir == 0 &&
- (!IS_GEN6(dev) || pm_iir == 0))
+ if (de_iir == 0 && gt_iir == 0 && (!IS_GEN6(dev) || pm_iir == 0))
goto done;
ret = IRQ_HANDLED;
@@ -804,10 +802,15 @@
/* check event from PCH */
if (de_iir & DE_PCH_EVENT) {
+ u32 pch_iir = I915_READ(SDEIIR);
+
if (HAS_PCH_CPT(dev))
cpt_irq_handler(dev, pch_iir);
else
ibx_irq_handler(dev, pch_iir);
+
+ /* should clear PCH hotplug event before clear CPU irq */
+ I915_WRITE(SDEIIR, pch_iir);
}
if (IS_GEN5(dev) && de_iir & DE_PCU_EVENT)
@@ -816,8 +819,6 @@
if (IS_GEN6(dev) && pm_iir & GEN6_PM_DEFERRED_EVENTS)
gen6_queue_rps_work(dev_priv, pm_iir);
- /* should clear PCH hotplug event before clear CPU irq */
- I915_WRITE(SDEIIR, pch_iir);
I915_WRITE(GTIIR, gt_iir);
I915_WRITE(DEIIR, de_iir);
I915_WRITE(GEN6_PMIIR, pm_iir);