From 05eff845a28499762075d3a72e238a31f4d2407c Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Wed, 19 Nov 2008 14:03:05 -0800 Subject: [PATCH] drm/i915: Always read pipestat in irq_handler Because we write pipestat before iir, it's possible that a pipestat interrupt will occur between the pipestat write and the iir write. This leaves pipestat with an interrupt status not visible in iir. This may cause an interrupt flood as we never clear the pipestat event. Signed-off-by: Keith Packard Signed-off-by: Eric Anholt Signed-off-by: Dave Airlie --- drivers/gpu/drm/i915/i915_irq.c | 55 +++++++++++++++++++++------------ 1 file changed, 36 insertions(+), 19 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 654d42fabec..c3673581db5 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -170,37 +170,54 @@ irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS) drm_i915_private_t *dev_priv = (drm_i915_private_t *) dev->dev_private; u32 iir, new_iir; u32 pipea_stats, pipeb_stats; + u32 vblank_status; + u32 vblank_enable; int vblank = 0; unsigned long irqflags; + int irq_received; + int ret = IRQ_NONE; atomic_inc(&dev_priv->irq_received); iir = I915_READ(IIR); - if (iir == 0) - return IRQ_NONE; + if (IS_I965G(dev)) { + vblank_status = I915_START_VBLANK_INTERRUPT_STATUS; + vblank_enable = PIPE_START_VBLANK_INTERRUPT_ENABLE; + } else { + vblank_status = I915_VBLANK_INTERRUPT_STATUS; + vblank_enable = I915_VBLANK_INTERRUPT_ENABLE; + } - do { - pipea_stats = 0; - pipeb_stats = 0; + for (;;) { + irq_received = iir != 0; + + /* Can't rely on pipestat interrupt bit in iir as it might + * have been cleared after the pipestat interrupt was received. + * It doesn't set the bit in iir again, but it still produces + * interrupts (for non-MSI). + */ + spin_lock_irqsave(&dev_priv->user_irq_lock, irqflags); + pipea_stats = I915_READ(PIPEASTAT); + pipeb_stats = I915_READ(PIPEBSTAT); /* * Clear the PIPE(A|B)STAT regs before the IIR */ - if (iir & I915_DISPLAY_PIPE_A_EVENT_INTERRUPT) { - spin_lock_irqsave(&dev_priv->user_irq_lock, irqflags); - pipea_stats = I915_READ(PIPEASTAT); + if (pipea_stats & 0x8000ffff) { I915_WRITE(PIPEASTAT, pipea_stats); - spin_unlock_irqrestore(&dev_priv->user_irq_lock, - irqflags); + irq_received = 1; } - if (iir & I915_DISPLAY_PIPE_B_EVENT_INTERRUPT) { - spin_lock_irqsave(&dev_priv->user_irq_lock, irqflags); - pipeb_stats = I915_READ(PIPEBSTAT); + if (pipeb_stats & 0x8000ffff) { I915_WRITE(PIPEBSTAT, pipeb_stats); - spin_unlock_irqrestore(&dev_priv->user_irq_lock, - irqflags); + irq_received = 1; } + spin_unlock_irqrestore(&dev_priv->user_irq_lock, irqflags); + + if (!irq_received) + break; + + ret = IRQ_HANDLED; I915_WRITE(IIR, iir); new_iir = I915_READ(IIR); /* Flush posted writes */ @@ -214,12 +231,12 @@ irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS) DRM_WAKEUP(&dev_priv->irq_queue); } - if (pipea_stats & I915_VBLANK_INTERRUPT_STATUS) { + if (pipea_stats & vblank_status) { vblank++; drm_handle_vblank(dev, 0); } - if (pipeb_stats & I915_VBLANK_INTERRUPT_STATUS) { + if (pipeb_stats & vblank_status) { vblank++; drm_handle_vblank(dev, 1); } @@ -244,9 +261,9 @@ irqreturn_t i915_driver_irq_handler(DRM_IRQ_ARGS) * stray interrupts. */ iir = new_iir; - } while (iir != 0); + } - return IRQ_HANDLED; + return ret; } static int i915_emit_irq(struct drm_device * dev) -- 2.41.1