A HPD interrupt may fire during intel_crt_detect_hotplug() - especially
when HPD interrupt storms occur.
Since the interrupt handler changes the enabled interrupt lines when it
detects a storm this races with intel_crt_detect_hotplug().
To avoid this, shiled the rmw cycles with IRQ save spinlocks.
Signed-off-by: Egbert Eich <e...@suse.de>
---
drivers/gpu/drm/i915/intel_crt.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index af5e43b..685f3de 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -376,9 +376,10 @@ static bool intel_crt_detect_hotplug(struct drm_connector
*connector)
{
struct drm_device *dev = connector->dev;
struct drm_i915_private *dev_priv = dev->dev_private;
- u32 hotplug_en, orig, stat;
+ u32 hotplug_en, stat;
bool ret = false;
int i, tries = 0;
+ unsigned long irqflags;
if (HAS_PCH_SPLIT(dev))
return intel_ironlake_crt_detect_hotplug(connector);
@@ -395,12 +396,14 @@ static bool intel_crt_detect_hotplug(struct drm_connector
*connector)
tries = 2;
else
tries = 1;
- hotplug_en = orig = I915_READ(PORT_HOTPLUG_EN);
- hotplug_en |= CRT_HOTPLUG_FORCE_DETECT;
for (i = 0; i < tries ; i++) {
/* turn on the FORCE_DETECT */
- I915_WRITE(PORT_HOTPLUG_EN, hotplug_en);
+ spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+ hotplug_en = I915_READ(PORT_HOTPLUG_EN);
+ I915_WRITE(PORT_HOTPLUG_EN, hotplug_en |
+ CRT_HOTPLUG_FORCE_DETECT);
+ spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
/* wait for FORCE_DETECT to go off */
if (wait_for((I915_READ(PORT_HOTPLUG_EN) &
CRT_HOTPLUG_FORCE_DETECT) == 0,
@@ -416,7 +419,11 @@ static bool intel_crt_detect_hotplug(struct drm_connector
*connector)
I915_WRITE(PORT_HOTPLUG_STAT, CRT_HOTPLUG_INT_STATUS);
/* and put the bits back */
- I915_WRITE(PORT_HOTPLUG_EN, orig);
+ spin_lock_irqsave(&dev_priv->irq_lock, irqflags);
+ hotplug_en = I915_READ(PORT_HOTPLUG_EN);
+ hotplug_en &= ~CRT_HOTPLUG_FORCE_DETECT;
+ I915_WRITE(PORT_HOTPLUG_EN, hotplug_en);
+ spin_unlock_irqrestore(&dev_priv->irq_lock, irqflags);
return ret;
}
--
1.8.4.5
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