We do not need to do a posting read of our uncached mmio write to re-enable the master interrupt lines after handling an interrupt, so don't. This saves us a slow UC read before we can process the interrupt, most noticeable in execlists where any stalls imposes extra latency on GPU command execution.
Signed-off-by: Chris Wilson <[email protected]> --- drivers/gpu/drm/i915/i915_irq.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 46aaef5c1851..0bd8b4df1bff 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -2131,7 +2131,6 @@ static irqreturn_t valleyview_irq_handler(int irq, void *arg) I915_WRITE(VLV_IER, ier); I915_WRITE(VLV_MASTER_IER, MASTER_INTERRUPT_ENABLE); - POSTING_READ(VLV_MASTER_IER); if (gt_iir) snb_gt_irq_handler(dev_priv, gt_iir); @@ -2216,7 +2215,6 @@ static irqreturn_t cherryview_irq_handler(int irq, void *arg) I915_WRITE(VLV_IER, ier); I915_WRITE(GEN8_MASTER_IRQ, GEN8_MASTER_IRQ_CONTROL); - POSTING_READ(GEN8_MASTER_IRQ); gen8_gt_irq_handler(dev_priv, master_ctl, gt_iir); @@ -2548,7 +2546,6 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg) /* disable master interrupt before clearing iir */ de_ier = I915_READ(DEIER); I915_WRITE(DEIER, de_ier & ~DE_MASTER_IRQ_CONTROL); - POSTING_READ(DEIER); /* Disable south interrupts. We'll only write to SDEIIR once, so further * interrupts will will be stored on its back queue, and then we'll be @@ -2558,7 +2555,6 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg) if (!HAS_PCH_NOP(dev_priv)) { sde_ier = I915_READ(SDEIER); I915_WRITE(SDEIER, 0); - POSTING_READ(SDEIER); } /* Find, clear, then process each source of interrupt */ @@ -2593,11 +2589,8 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg) } I915_WRITE(DEIER, de_ier); - POSTING_READ(DEIER); - if (!HAS_PCH_NOP(dev_priv)) { + if (!HAS_PCH_NOP(dev_priv)) I915_WRITE(SDEIER, sde_ier); - POSTING_READ(SDEIER); - } /* IRQs are synced during runtime_suspend, we don't require a wakeref */ enable_rpm_wakeref_asserts(dev_priv); -- 2.18.0 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
