[Intel-gfx] [KERNEL] Regression bug in drm/i915, Wrong assumption in commit e11aa36 breaks suspend on at least lenovo x61

[Imre Deak]

On ke, 2015-02-18 at 17:39 +0200, Jani Nikula wrote:
> On Tue, 17 Feb 2015, Klaus Ethgen <Klaus+lkml at ethgen.de> wrote:
> > After solving  the conflicts, I applied the revert (see attachment) to
> > v3.18.7. I think it should also apply to the current head. With that
> > patch, suspend is working again on that version.
> >
> > However, I have not to deep knowledge of that subsystem, so please,
> > someone who have, have a deeper look into it. I especially do not know
> > if the lines in .../intel_pm.c are correct or better leaving them as
> > they are in v3.18.7.
> >
> > I want to have it working on a version that I know is stable before
> > asking to pull it to head.
> 
> Hi Klaus, we fear this patch may hide the actual cause. Would be useful
> to get a better description of what happens, along with a dmesg with
> drm.debug=14 module parameter set. This might clutter the mailing list,
> would you mind filing a bug at [1] and attach the info there?
> 
> Thanks,
> Jani.
> 
> [1] https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel

In addition to the above could you also try the following patch and
provide a dmesg log on the bugzilla ticket - at this point only to try
to narrow down the issue?:

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index d358ce8..02c65f4 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -4466,6 +4466,14 @@ 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)) {
+		if (printk_ratelimit())
+			DRM_ERROR("spurious/shared interrupt iir %08x imr %08x ier %08x\n",
+				  I915_READ(IIR), I915_READ(IMR), I915_READ(IER));
+
+		return IRQ_NONE;
+	}
+
 	iir = I915_READ(IIR);
 
 	for (;;) {
@@ -4766,7 +4774,10 @@ void intel_runtime_pm_disable_interrupts(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	dev->driver->irq_uninstall(dev);
+
+	spin_lock_irq(&dev_priv->irq_lock);
 	dev_priv->pm._irqs_disabled = true;
+	spin_unlock_irq(&dev_priv->irq_lock);
 }
 
 /* Restore interrupts so we can recover from runtime PM. */
@@ -4774,7 +4785,10 @@ void intel_runtime_pm_restore_interrupts(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	spin_lock_irq(&dev_priv->irq_lock);
 	dev_priv->pm._irqs_disabled = false;
+	spin_unlock_irq(&dev_priv->irq_lock);
+
 	dev->driver->irq_preinstall(dev);
 	dev->driver->irq_postinstall(dev);
 }