From 2dd2a883aad7c852400027c2261bcab69d9e238e Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Tue, 24 Feb 2015 11:14:30 +0200 Subject: [PATCH] drm/i915: avoid processing spurious/shared interrupts in low-power states Atm, it's possible that the interrupt handler is called when the device is in D3 or some other low-power state. It can be due to another device that is still in D0 state and shares the interrupt line with i915, or on some platforms there could be spurious interrupts even without sharing the interrupt line. The latter case was reported by Klaus Ethgen using a Lenovo x61p machine (gen 4). He noticed this issue via a system suspend/resume hang and bisected it to the following commit: commit e11aa362308f5de467ce355a2a2471321b15a35c Author: Jesse Barnes Date: Wed Jun 18 09:52:55 2014 -0700 drm/i915: use runtime irq suspend/resume in freeze/thaw This is a problem, since in low-power states IIR will always read 0xffffffff resulting in an endless IRQ servicing loop. Fix this by handling interrupts only when the driver explicitly enables them and so it's guaranteed that the interrupt registers return a valid value. Note that this issue existed even before the above commit, since during runtime suspend/resume we never unregistered the handler. v2: - clarify the purpose of smp_mb() vs. synchronize_irq() in the code comment (Chris) v3: - no need for an explicit smp_mb(), we can assume that synchronize_irq() and the mmio read/writes in the install hooks provide for this (Daniel) - remove code comment as the remaining synchronize_irq() is self explanatory (Daniel) v4: - drm_irq_uninstall() implies synchronize_irq(), so no need to call it explicitly (Daniel) Reference: https://lkml.org/lkml/2015/2/11/205 Reported-and-bisected-by: Klaus Ethgen Cc: stable@vger.kernel.org Signed-off-by: Imre Deak Reviewed-by: Daniel Vetter Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/i915_irq.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index 4145d95902f5..ede5bbbd8a08 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -1892,6 +1892,9 @@ static irqreturn_t valleyview_irq_handler(int irq, void *arg) u32 iir, gt_iir, pm_iir; irqreturn_t ret = IRQ_NONE; + if (!intel_irqs_enabled(dev_priv)) + return IRQ_NONE; + while (true) { /* Find, clear, then process each source of interrupt */ @@ -1936,6 +1939,9 @@ static irqreturn_t cherryview_irq_handler(int irq, void *arg) u32 master_ctl, iir; irqreturn_t ret = IRQ_NONE; + if (!intel_irqs_enabled(dev_priv)) + return IRQ_NONE; + for (;;) { master_ctl = I915_READ(GEN8_MASTER_IRQ) & ~GEN8_MASTER_IRQ_CONTROL; iir = I915_READ(VLV_IIR); @@ -2208,6 +2214,9 @@ static irqreturn_t ironlake_irq_handler(int irq, void *arg) u32 de_iir, gt_iir, de_ier, sde_ier = 0; irqreturn_t ret = IRQ_NONE; + if (!intel_irqs_enabled(dev_priv)) + return IRQ_NONE; + /* We get interrupts on unclaimed registers, so check for this before we * do any I915_{READ,WRITE}. */ intel_uncore_check_errors(dev); @@ -2279,6 +2288,9 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg) enum pipe pipe; u32 aux_mask = GEN8_AUX_CHANNEL_A; + if (!intel_irqs_enabled(dev_priv)) + return IRQ_NONE; + if (IS_GEN9(dev)) aux_mask |= GEN9_AUX_CHANNEL_B | GEN9_AUX_CHANNEL_C | GEN9_AUX_CHANNEL_D; @@ -3771,6 +3783,9 @@ static irqreturn_t i8xx_irq_handler(int irq, void *arg) I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT | I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT; + if (!intel_irqs_enabled(dev_priv)) + return IRQ_NONE; + iir = I915_READ16(IIR); if (iir == 0) return IRQ_NONE; @@ -3951,6 +3966,9 @@ static irqreturn_t i915_irq_handler(int irq, void *arg) I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT; int pipe, ret = IRQ_NONE; + if (!intel_irqs_enabled(dev_priv)) + return IRQ_NONE; + iir = I915_READ(IIR); do { bool irq_received = (iir & ~flip_mask) != 0; @@ -4171,6 +4189,9 @@ static irqreturn_t i965_irq_handler(int irq, void *arg) I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT | I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT; + if (!intel_irqs_enabled(dev_priv)) + return IRQ_NONE; + iir = I915_READ(IIR); for (;;) { @@ -4520,6 +4541,7 @@ void intel_runtime_pm_disable_interrupts(struct drm_i915_private *dev_priv) { dev_priv->dev->driver->irq_uninstall(dev_priv->dev); dev_priv->pm.irqs_enabled = false; + synchronize_irq(dev_priv->dev->irq); } /** -- 2.20.1